spanner

package module
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 Go to latest Published: Jul 1, 2024 License: Apache-2.0 Imports: 62 Imported by: 935

README

Cloud Spanner Go Reference

Example Usage

First create a spanner.Client to use throughout your application:

client, err := spanner.NewClient(ctx, "projects/P/instances/I/databases/D")
if err != nil {
	log.Fatal(err)
}

// Simple Reads And Writes
_, err = client.Apply(ctx, []*spanner.Mutation{
	spanner.Insert("Users",
		[]string{"name", "email"},
		[]interface{}{"alice", "a@example.com"})})
if err != nil {
	log.Fatal(err)
}
row, err := client.Single().ReadRow(ctx, "Users",
	spanner.Key{"alice"}, []string{"email"})
if err != nil {
	log.Fatal(err)
}

Session Leak

A Client object of the Client Library has a limit on the number of maximum sessions. For example the default value of MaxOpened, which is the maximum number of sessions allowed by the session pool in the Golang Client Library, is 400. You can configure these values at the time of creating a Client by passing custom SessionPoolConfig as part of ClientConfig. When all the sessions are checked out of the session pool, every new transaction has to wait until a session is returned to the pool. If a session is never returned to the pool (hence causing a session leak), the transactions will have to wait indefinitely and your application will be blocked.

Common Root Causes

The most common reason for session leaks in the Golang client library are:

  1. Not stopping a RowIterator that is returned by Query, Read and other methods. Always use RowIterator.Stop() to ensure that the RowIterator is always closed.
  2. Not closing a ReadOnlyTransaction when you no longer need it. Always call ReadOnlyTransaction.Close() after use, to ensure that the ReadOnlyTransaction is always closed.

As shown in the example below, the txn.Close() statement releases the session after it is complete. If you fail to call txn.Close(), the session is not released back to the pool. The recommended way is to use defer as shown below.

client, err := spanner.NewClient(ctx, "projects/P/instances/I/databases/D")
if err != nil {
  log.Fatal(err)
}
txn := client.ReadOnlyTransaction()
defer txn.Close()
Debugging and Resolving Session Leaks
Logging inactive transactions

This option logs warnings when you have exhausted >95% of your session pool. It is enabled by default. This could mean two things; either you need to increase the max sessions in your session pool (as the number of queries run using the client side database object is greater than your session pool can serve), or you may have a session leak. To help debug which transactions may be causing this session leak, the logs will also contain stack traces of transactions which have been running longer than expected if TrackSessionHandles under SessionPoolConfig is enabled.

sessionPoolConfig := spanner.SessionPoolConfig{
    TrackSessionHandles: true,
    InactiveTransactionRemovalOptions: spanner.InactiveTransactionRemovalOptions{
      ActionOnInactiveTransaction: spanner.Warn,
    },
}
client, err := spanner.NewClientWithConfig(
	ctx, database, spanner.ClientConfig{SessionPoolConfig: sessionPoolConfig},
)
if err != nil {
	log.Fatal(err)
}
defer client.Close()

// Example Log message to warn presence of long running transactions
// session <session-info> checked out of pool at <session-checkout-time> is long running due to possible session leak for goroutine
// <Stack Trace of transaction>
Automatically clean inactive transactions

When the option to automatically clean inactive transactions is enabled, the client library will automatically detect problematic transactions that are running for a very long time (thus causing session leaks) and close them. The session will be removed from the pool and be replaced by a new session. To dig deeper into which transactions are being closed, you can check the logs to see the stack trace of the transactions which might be causing these leaks and further debug them.

sessionPoolConfig := spanner.SessionPoolConfig{
    TrackSessionHandles: true,
    InactiveTransactionRemovalOptions: spanner.InactiveTransactionRemovalOptions{
      ActionOnInactiveTransaction: spanner.WarnAndClose,
    },
}
client, err := spanner.NewClientWithConfig(
	ctx, database, spanner.ClientConfig{SessionPoolConfig: sessionPoolConfig},
)
if err != nil {
log.Fatal(err)
}
defer client.Close()

// Example Log message for when transaction is recycled
// session <session-info> checked out of pool at <session-checkout-time> is long running and will be removed due to possible session leak for goroutine 
// <Stack Trace of transaction>

Documentation

Overview

Package spanner provides a client for reading and writing to Cloud Spanner databases. See the packages under admin for clients that operate on databases and instances.

See https://cloud.google.com/spanner/docs/getting-started/go/ for an introduction to Cloud Spanner and additional help on using this API.

See https://godoc.org/cloud.google.com/go for authentication, timeouts, connection pooling and similar aspects of this package.

Creating a Client

To start working with this package, create a client that refers to the database of interest: 

ctx := context.Background()
client, err := spanner.NewClient(ctx, "projects/P/instances/I/databases/D")
if err != nil {
    // TODO: Handle error.
}
defer client.Close()

Remember to close the client after use to free up the sessions in the session pool.

To use an emulator with this library, you can set the SPANNER_EMULATOR_HOST environment variable to the address at which your emulator is running. This will send requests to that address instead of to Cloud Spanner. You can then create and use a client as usual: 

// Set SPANNER_EMULATOR_HOST environment variable.
err := os.Setenv("SPANNER_EMULATOR_HOST", "localhost:9010")
if err != nil {
    // TODO: Handle error.
}
// Create client as usual.
client, err := spanner.NewClient(ctx, "projects/P/instances/I/databases/D")
if err != nil {
    // TODO: Handle error.
}

Simple Reads and Writes

Two Client methods, Apply and Single, work well for simple reads and writes. As a quick introduction, here we write a new row to the database and read it back: 

_, err := client.Apply(ctx, []*spanner.Mutation{
    spanner.Insert("Users",
        []string{"name", "email"},
        []interface{}{"alice", "a@example.com"})})
if err != nil {
    // TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Users",
    spanner.Key{"alice"}, []string{"email"})
if err != nil {
    // TODO: Handle error.
}

All the methods used above are discussed in more detail below.

Keys

Every Cloud Spanner row has a unique key, composed of one or more columns. Construct keys with a literal of type Key: 

key1 := spanner.Key{"alice"}

KeyRanges

The keys of a Cloud Spanner table are ordered. You can specify ranges of keys using the KeyRange type: 

kr1 := spanner.KeyRange{Start: key1, End: key2}

By default, a KeyRange includes its start key but not its end key. Use the Kind field to specify other boundary conditions: 

// include both keys
kr2 := spanner.KeyRange{Start: key1, End: key2, Kind: spanner.ClosedClosed}

KeySets

A KeySet represents a set of keys. A single Key or KeyRange can act as a KeySet. Use the KeySets function to build the union of several KeySets: 

ks1 := spanner.KeySets(key1, key2, kr1, kr2)

AllKeys returns a KeySet that refers to all the keys in a table: 

ks2 := spanner.AllKeys()

Transactions

All Cloud Spanner reads and writes occur inside transactions. There are two types of transactions, read-only and read-write. Read-only transactions cannot change the database, do not acquire locks, and may access either the current database state or states in the past. Read-write transactions can read the database before writing to it, and always apply to the most recent database state.

Single Reads

The simplest and fastest transaction is a ReadOnlyTransaction that supports a single read operation. Use Client.Single to create such a transaction. You can chain the call to Single with a call to a Read method.

When you only want one row whose key you know, use ReadRow. Provide the table name, key, and the columns you want to read: 

row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})

Read multiple rows with the Read method. It takes a table name, KeySet, and list of columns: 

iter := client.Single().Read(ctx, "Accounts", keyset1, columns)

Read returns a RowIterator. You can call the Do method on the iterator and pass a callback: 

err := iter.Do(func(row *Row) error {
   // TODO: use row
   return nil
})

RowIterator also follows the standard pattern for the Google Cloud Client Libraries: 

defer iter.Stop()
for {
    row, err := iter.Next()
    if err == iterator.Done {
        break
    }
    if err != nil {
        // TODO: Handle error.
    }
    // TODO: use row
}

Always call Stop when you finish using an iterator this way, whether or not you iterate to the end. (Failing to call Stop could lead you to exhaust the database's session quota.)

To read rows with an index, use ReadUsingIndex.

Statements

The most general form of reading uses SQL statements. Construct a Statement with NewStatement, setting any parameters using the Statement's Params map: 

stmt := spanner.NewStatement("SELECT First, Last FROM SINGERS WHERE Last >= @start")
stmt.Params["start"] = "Dylan"

You can also construct a Statement directly with a struct literal, providing your own map of parameters.

Use the Query method to run the statement and obtain an iterator: 

iter := client.Single().Query(ctx, stmt)

Rows

Once you have a Row, via an iterator or a call to ReadRow, you can extract column values in several ways. Pass in a pointer to a Go variable of the appropriate type when you extract a value.

You can extract by column position or name: 

err := row.Column(0, &name)
err = row.ColumnByName("balance", &balance)

You can extract all the columns at once: 

err = row.Columns(&name, &balance)

Or you can define a Go struct that corresponds to your columns, and extract into that: 

var s struct { Name string; Balance int64 }
err = row.ToStruct(&s)

For Cloud Spanner columns that may contain NULL, use one of the NullXXX types, like NullString: 

var ns spanner.NullString
if err := row.Column(0, &ns); err != nil {
    // TODO: Handle error.
}
if ns.Valid {
    fmt.Println(ns.StringVal)
} else {
    fmt.Println("column is NULL")
}

Multiple Reads

To perform more than one read in a transaction, use ReadOnlyTransaction: 

txn := client.ReadOnlyTransaction()
defer txn.Close()
iter := txn.Query(ctx, stmt1)
// ...
iter =  txn.Query(ctx, stmt2)
// ...

You must call Close when you are done with the transaction.

Timestamps and Timestamp Bounds

Cloud Spanner read-only transactions conceptually perform all their reads at a single moment in time, called the transaction's read timestamp. Once a read has started, you can call ReadOnlyTransaction's Timestamp method to obtain the read timestamp.

By default, a transaction will pick the most recent time (a time where all previously committed transactions are visible) for its reads. This provides the freshest data, but may involve some delay. You can often get a quicker response if you are willing to tolerate "stale" data. You can control the read timestamp selected by a transaction by calling the WithTimestampBound method on the transaction before using it. For example, to perform a query on data that is at most one minute stale, use 

client.Single().
    WithTimestampBound(spanner.MaxStaleness(1*time.Minute)).
    Query(ctx, stmt)

See the documentation of TimestampBound for more details.

Mutations

To write values to a Cloud Spanner database, construct a Mutation. The spanner package has functions for inserting, updating and deleting rows. Except for the Delete methods, which take a Key or KeyRange, each mutation-building function comes in three varieties.

One takes lists of columns and values along with the table name: 

m1 := spanner.Insert("Users",
    []string{"name", "email"},
    []interface{}{"alice", "a@example.com"})

One takes a map from column names to values: 

m2 := spanner.InsertMap("Users", map[string]interface{}{
    "name":  "alice",
    "email": "a@example.com",
})

And the third accepts a struct value, and determines the columns from the struct field names: 

type User struct { Name, Email string }
u := User{Name: "alice", Email: "a@example.com"}
m3, err := spanner.InsertStruct("Users", u)

Writes

To apply a list of mutations to the database, use Apply: 

_, err := client.Apply(ctx, []*spanner.Mutation{m1, m2, m3})

If you need to read before writing in a single transaction, use a ReadWriteTransaction. ReadWriteTransactions may be aborted automatically by the backend and need to be retried. You pass in a function to ReadWriteTransaction, and the client will handle the retries automatically. Use the transaction's BufferWrite method to buffer mutations, which will all be executed at the end of the transaction: 

_, err := client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
    var balance int64
    row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
    if err != nil {
        // The transaction function will be called again if the error code
        // of this error is Aborted. The backend may automatically abort
        // any read/write transaction if it detects a deadlock or other
        // problems.
        return err
    }
    if err := row.Column(0, &balance); err != nil {
        return err
    }

    if balance <= 10 {
        return errors.New("insufficient funds in account")
    }
    balance -= 10
    m := spanner.Update("Accounts", []string{"user", "balance"}, []interface{}{"alice", balance})
    // The buffered mutation will be committed.  If the commit
    // fails with an Aborted error, this function will be called
    // again.
    return txn.BufferWrite([]*spanner.Mutation{m})
})

Structs

Cloud Spanner STRUCT (aka STRUCT) values (https://cloud.google.com/spanner/docs/data-types#struct-type) can be represented by a Go struct value.

A proto StructType is built from the field types and field tag information of the Go struct. If a field in the struct type definition has a "spanner:<field_name>" tag, then the value of the "spanner" key in the tag is used as the name for that field in the built StructType, otherwise the field name in the struct definition is used. To specify a field with an empty field name in a Cloud Spanner STRUCT type, use the `spanner:""` tag annotation against the corresponding field in the Go struct's type definition.

A STRUCT value can contain STRUCT-typed and Array-of-STRUCT typed fields and these can be specified using named struct-typed and []struct-typed fields inside a Go struct. However, embedded struct fields are not allowed. Unexported struct fields are ignored.

NULL STRUCT values in Cloud Spanner are typed. A nil pointer to a Go struct value can be used to specify a NULL STRUCT value of the corresponding StructType. Nil and empty slices of a Go STRUCT type can be used to specify NULL and empty array values respectively of the corresponding StructType. A slice of pointers to a Go struct type can be used to specify an array of NULL-able STRUCT values.

DML and Partitioned DML

Spanner supports DML statements like INSERT, UPDATE and DELETE. Use ReadWriteTransaction.Update to run DML statements. It returns the number of rows affected. (You can call use ReadWriteTransaction.Query with a DML statement. The first call to Next on the resulting RowIterator will return iterator.Done, and the RowCount field of the iterator will hold the number of affected rows.)

For large databases, it may be more efficient to partition the DML statement. Use client.PartitionedUpdate to run a DML statement in this way. Not all DML statements can be partitioned.

Tracing

This client has been instrumented to use OpenCensus tracing (http://opencensus.io). To enable tracing, see "Enabling Tracing for a Program" at https://godoc.org/go.opencensus.io/trace. OpenCensus tracing requires Go 1.8 or higher.

Index

Examples

Constants

View Source 
const (
	// Scope is the scope for Cloud Spanner Data API.
	Scope = "https://www.googleapis.com/auth/spanner.data"

	// AdminScope is the scope for Cloud Spanner Admin APIs.
	AdminScope = "https://www.googleapis.com/auth/spanner.admin"
)
View Source 
const (

	// NumericPrecisionDigits is the maximum number of digits in a NUMERIC
	// value.
	NumericPrecisionDigits = 38

	// NumericScaleDigits is the maximum number of digits after the decimal
	// point in a NUMERIC value.
	NumericScaleDigits = 9
)
View Source 
const OtInstrumentationScope = "cloud.google.com/go"

OtInstrumentationScope is the instrumentation name that will be associated with the emitted telemetry.

Variables

View Source 
var (
	// OpenSessionCount is a measure of the number of sessions currently opened.
	// It is EXPERIMENTAL and subject to change or removal without notice.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get open_session_count metrics.
	OpenSessionCount = stats.Int64(
		statsPrefix+"open_session_count",
		"Number of sessions currently opened",
		stats.UnitDimensionless,
	)

	// OpenSessionCountView is a view of the last value of OpenSessionCount.
	// It is EXPERIMENTAL and subject to change or removal without notice.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get open_session_count metrics.
	OpenSessionCountView = &view.View{
		Measure:     OpenSessionCount,
		Aggregation: view.LastValue(),
		TagKeys:     tagCommonKeys,
	}

	// MaxAllowedSessionsCount is a measure of the maximum number of sessions
	// allowed. Configurable by the user.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get max_allowed_sessions metrics.
	MaxAllowedSessionsCount = stats.Int64(
		statsPrefix+"max_allowed_sessions",
		"The maximum number of sessions allowed. Configurable by the user.",
		stats.UnitDimensionless,
	)

	// MaxAllowedSessionsCountView is a view of the last value of
	// MaxAllowedSessionsCount.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get max_allowed_sessions metrics.
	MaxAllowedSessionsCountView = &view.View{
		Measure:     MaxAllowedSessionsCount,
		Aggregation: view.LastValue(),
		TagKeys:     tagCommonKeys,
	}

	// SessionsCount is a measure of the number of sessions in the pool
	// including both in-use, idle, and being prepared.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get num_sessions_in_pool metrics.
	SessionsCount = stats.Int64(
		statsPrefix+"num_sessions_in_pool",
		"The number of sessions currently in use.",
		stats.UnitDimensionless,
	)

	// SessionsCountView is a view of the last value of SessionsCount.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get num_sessions_in_pool metrics.
	SessionsCountView = &view.View{
		Measure:     SessionsCount,
		Aggregation: view.LastValue(),
		TagKeys:     append(tagCommonKeys, tagKeyType),
	}

	// MaxInUseSessionsCount is a measure of the maximum number of sessions
	// in use during the last 10 minute interval.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get max_in_use_sessions metrics.
	MaxInUseSessionsCount = stats.Int64(
		statsPrefix+"max_in_use_sessions",
		"The maximum number of sessions in use during the last 10 minute interval.",
		stats.UnitDimensionless,
	)

	// MaxInUseSessionsCountView is a view of the last value of
	// MaxInUseSessionsCount.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get max_in_use_sessions metrics.
	MaxInUseSessionsCountView = &view.View{
		Measure:     MaxInUseSessionsCount,
		Aggregation: view.LastValue(),
		TagKeys:     tagCommonKeys,
	}

	// GetSessionTimeoutsCount is a measure of the number of get sessions
	// timeouts due to pool exhaustion.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get get_session_timeouts metrics.
	GetSessionTimeoutsCount = stats.Int64(
		statsPrefix+"get_session_timeouts",
		"The number of get sessions timeouts due to pool exhaustion.",
		stats.UnitDimensionless,
	)

	// GetSessionTimeoutsCountView is a view of the last value of
	// GetSessionTimeoutsCount.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get get_session_timeouts metrics.
	GetSessionTimeoutsCountView = &view.View{
		Measure:     GetSessionTimeoutsCount,
		Aggregation: view.Count(),
		TagKeys:     tagCommonKeys,
	}

	// AcquiredSessionsCount is the number of sessions acquired from
	// the session pool.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get num_acquired_sessions metrics.
	AcquiredSessionsCount = stats.Int64(
		statsPrefix+"num_acquired_sessions",
		"The number of sessions acquired from the session pool.",
		stats.UnitDimensionless,
	)

	// AcquiredSessionsCountView is a view of the last value of
	// AcquiredSessionsCount.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get num_acquired_sessions metrics.
	AcquiredSessionsCountView = &view.View{
		Measure:     AcquiredSessionsCount,
		Aggregation: view.Count(),
		TagKeys:     tagCommonKeys,
	}

	// ReleasedSessionsCount is the number of sessions released by the user
	// and pool maintainer.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get num_released_sessions metrics.
	ReleasedSessionsCount = stats.Int64(
		statsPrefix+"num_released_sessions",
		"The number of sessions released by the user and pool maintainer.",
		stats.UnitDimensionless,
	)

	// ReleasedSessionsCountView is a view of the last value of
	// ReleasedSessionsCount.
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get num_released_sessions metrics.
	ReleasedSessionsCountView = &view.View{
		Measure:     ReleasedSessionsCount,
		Aggregation: view.Count(),
		TagKeys:     tagCommonKeys,
	}

	// GFELatency is the latency between Google's network receiving an RPC and reading back the first byte of the response
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get gfe_latency metrics.
	GFELatency = stats.Int64(
		statsPrefix+"gfe_latency",
		"Latency between Google's network receiving an RPC and reading back the first byte of the response",
		stats.UnitMilliseconds,
	)

	// GFELatencyView is the view of distribution of GFELatency values
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get gfe_latency metrics.
	GFELatencyView = &view.View{
		Name:        "cloud.google.com/go/spanner/gfe_latency",
		Measure:     GFELatency,
		Description: "Latency between Google's network receives an RPC and reads back the first byte of the response",
		Aggregation: view.Distribution(0.0, 0.01, 0.05, 0.1, 0.3, 0.6, 0.8, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 8.0, 10.0, 13.0,
			16.0, 20.0, 25.0, 30.0, 40.0, 50.0, 65.0, 80.0, 100.0, 130.0, 160.0, 200.0, 250.0,
			300.0, 400.0, 500.0, 650.0, 800.0, 1000.0, 2000.0, 5000.0, 10000.0, 20000.0, 50000.0,
			100000.0),
		TagKeys: append(tagCommonKeys, tagKeyMethod),
	}

	// GFEHeaderMissingCount is the number of RPC responses received without the server-timing header, most likely means that the RPC never reached Google's network
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get gfe_header_missing_count metrics.
	GFEHeaderMissingCount = stats.Int64(
		statsPrefix+"gfe_header_missing_count",
		"Number of RPC responses received without the server-timing header, most likely means that the RPC never reached Google's network",
		stats.UnitDimensionless,
	)

	// GFEHeaderMissingCountView is the view of number of GFEHeaderMissingCount
	//
	// Deprecated: OpenCensus project is deprecated. Use OpenTelemetry to get gfe_header_missing_count metrics.
	GFEHeaderMissingCountView = &view.View{
		Name:        "cloud.google.com/go/spanner/gfe_header_missing_count",
		Measure:     GFEHeaderMissingCount,
		Description: "Number of RPC responses received without the server-timing header, most likely means that the RPC never reached Google's network",
		Aggregation: view.Count(),
		TagKeys:     append(tagCommonKeys, tagKeyMethod),
	}
)
View Source 
var (
	// CommitTimestamp is a special value used to tell Cloud Spanner to insert
	// the commit timestamp of the transaction into a column. It can be used in
	// a Mutation, or directly used in InsertStruct or InsertMap. See
	// ExampleCommitTimestamp. This is just a placeholder and the actual value
	// stored in this variable has no meaning.
	CommitTimestamp = commitTimestamp
)
View Source 
var DefaultRetryBackoff = gax.Backoff{
	Initial:    20 * time.Millisecond,
	Max:        32 * time.Second,
	Multiplier: 1.3,
}

DefaultRetryBackoff is used for retryers as a fallback value when the server did not return any retry information.

View Source 
var DefaultSessionPoolConfig = SessionPoolConfig{
	MinOpened: 100,
	MaxOpened: numChannels * 100,
	MaxBurst:  10,

	WriteSessions:       0.2,
	HealthCheckWorkers:  10,
	HealthCheckInterval: healthCheckIntervalMins * time.Minute,
	InactiveTransactionRemovalOptions: InactiveTransactionRemovalOptions{
		ActionOnInactiveTransaction: Warn,
		// contains filtered or unexported fields
	},
	// contains filtered or unexported fields
}

DefaultSessionPoolConfig is the default configuration for the session pool that will be used for a Spanner client, unless the user supplies a specific session pool config.

View Source 
var (
	// ErrRowNotFound row not found error
	ErrRowNotFound = errors.New("row not found")
)

Functions

func DisableGfeLatencyAndHeaderMissingCountViews deprecated added in v1.29.0 

func DisableGfeLatencyAndHeaderMissingCountViews()

DisableGfeLatencyAndHeaderMissingCountViews disables GFEHeaderMissingCount and GFELatency metric

Deprecated: OpenCensus project is deprecated. Use OpenTelemetry for capturing metrics.

func EnableGfeHeaderMissingCountView deprecated added in v1.29.0 

func EnableGfeHeaderMissingCountView() error

EnableGfeHeaderMissingCountView enables GFEHeaderMissingCount metric

Deprecated: OpenCensus project is deprecated. Use EnableOpenTelemetryMetrics to get GfeHeaderMissingCount metrics through OpenTelemetry instrumentation.

func EnableGfeLatencyAndHeaderMissingCountViews deprecated added in v1.29.0 

func EnableGfeLatencyAndHeaderMissingCountViews() error

EnableGfeLatencyAndHeaderMissingCountViews enables GFEHeaderMissingCount and GFELatency metric

Deprecated: OpenCensus project is deprecated. Use EnableOpenTelemetryMetrics to get GfeLatency and GfeHeaderMissingCount metrics through OpenTelemetry instrumentation.

func EnableGfeLatencyView deprecated added in v1.29.0 

func EnableGfeLatencyView() error

EnableGfeLatencyView enables GFELatency metric

Deprecated: OpenCensus project is deprecated. Use EnableOpenTelemetryMetrics to get GfeLatency metrics through OpenTelemetry instrumentation.

func EnableOpenTelemetryMetrics added in v1.57.0 

func EnableOpenTelemetryMetrics()

EnableOpenTelemetryMetrics enables OpenTelemetery metrics

func EnableStatViews deprecated added in v1.5.0 

func EnableStatViews() error

EnableStatViews enables all views of metrics relate to session management.

Deprecated: OpenCensus project is deprecated. Use EnableOpenTelemetryMetrics to get Session metrics through OpenTelemetry instrumentation.

func ErrCode 

func ErrCode(err error) codes.Code

ErrCode extracts the canonical error code from a Go error.

func ErrDesc 

func ErrDesc(err error) string

ErrDesc extracts the Cloud Spanner error description from a Go error.

func ExtractRetryDelay added in v1.8.0 

func ExtractRetryDelay(err error) (time.Duration, bool)

ExtractRetryDelay extracts retry backoff from a *spanner.Error if present.

func IsOpenTelemetryMetricsEnabled added in v1.57.0 

func IsOpenTelemetryMetricsEnabled() bool

IsOpenTelemetryMetricsEnabled tells whether OpenTelemtery metrics is enabled or not.

func NumericString added in v1.10.0 

func NumericString(r *big.Rat) string

NumericString returns a string representing a *big.Rat in a format compatible with Spanner SQL. It returns a floating-point literal with 9 digits after the decimal point.

func SelectAll added in v1.56.0 

func SelectAll(rows rowIterator, destination interface{}, options ...DecodeOptions) error

SelectAll iterates all rows to the end. After iterating it closes the rows and propagates any errors that could pop up with destination slice partially filled. It expects that destination should be a slice. For each row, it scans data and appends it to the destination slice. SelectAll supports both types of slices: slice of pointers and slice of structs or primitives by value, for example: 

type Singer struct {
    ID    string
    Name  string
}

var singersByPtr []*Singer
var singersByValue []Singer

Both singersByPtr and singersByValue are valid destinations for SelectAll function.

Add the option `spanner.WithLenient()` to instruct SelectAll to ignore additional columns in the rows that are not present in the destination struct. example: 

var singersByPtr []*Singer
err := spanner.SelectAll(row, &singersByPtr, spanner.WithLenient())

func ToSpannerError added in v1.12.0 

func ToSpannerError(err error) error

ToSpannerError converts a general Go error to *spanner.Error. If the given error is already a *spanner.Error, the original error will be returned.

Spanner Errors are normally created by the Spanner client library from the returned APIError of a RPC. This method can also be used to create Spanner errors for use in tests. The recommended way to create test errors is calling this method with a status error, e.g. ToSpannerError(status.New(codes.NotFound, "Table not found").Err())

func UseNumberWithJSONDecoderEncoder added in v1.54.0 

func UseNumberWithJSONDecoderEncoder(useNumber bool)

UseNumberWithJSONDecoderEncoder specifies whether Cloud Spanner JSON numbers are decoded as Number (preserving precision) or float64 (risking loss). Defaults to the same behavior as the standard Go library, which means decoding to float64. Call this method to enable lossless precision. NOTE 1: Calling this method affects the behavior of all clients created by this library, both existing and future instances. NOTE 2: This method sets a global variable that is used by the client to encode/decode JSON numbers. Access to the global variable is not synchronized. You should only call this method when there are no goroutines encoding/decoding Cloud Spanner JSON values. It is recommended to only call this method during the initialization of your application, and preferably before you create any Cloud Spanner clients, and/or in tests when there are no queries being executed.

Types

type ActionOnInactiveTransactionKind added in v1.52.0 

type ActionOnInactiveTransactionKind int

ActionOnInactiveTransactionKind describes the kind of action taken when there are inactive transactions. 

const (

	// NoAction action does not perform any action on inactive transactions.
	NoAction ActionOnInactiveTransactionKind
	// Warn action logs inactive transactions. Any inactive transaction gets logged only once.
	Warn
	// Close action closes inactive transactions without logging.
	Close
	// WarnAndClose action logs and closes the inactive transactions.
	WarnAndClose
)

type ApplyOption 

type ApplyOption func(*applyOption)

An ApplyOption is an optional argument to Apply.

func ApplyAtLeastOnce 

func ApplyAtLeastOnce() ApplyOption

ApplyAtLeastOnce returns an ApplyOption that removes replay protection.

With this option, Apply may attempt to apply mutations more than once; if the mutations are not idempotent, this may lead to a failure being reported when the mutation was applied more than once. For example, an insert may fail with ALREADY_EXISTS even though the row did not exist before Apply was called. For this reason, most users of the library will prefer not to use this option. However, ApplyAtLeastOnce requires only a single RPC, whereas Apply's default replay protection may require an additional RPC. So this option may be appropriate for latency sensitive and/or high throughput blind writing.

func ExcludeTxnFromChangeStreams added in v1.61.0 

func ExcludeTxnFromChangeStreams() ApplyOption

ExcludeTxnFromChangeStreams returns an ApplyOptions that sets whether to exclude recording this commit operation from allowed tracking change streams.

func Priority added in v1.17.0 

func Priority(priority sppb.RequestOptions_Priority) ApplyOption

Priority returns an ApplyOptions that sets the RPC priority to use for the commit operation.

func TransactionTag added in v1.22.0 

func TransactionTag(tag string) ApplyOption

TransactionTag returns an ApplyOption that will include the given tag as a transaction tag for a write-only transaction.

type BatchReadOnlyTransaction 

type BatchReadOnlyTransaction struct {
	ReadOnlyTransaction
	ID BatchReadOnlyTransactionID
}

BatchReadOnlyTransaction is a ReadOnlyTransaction that allows for exporting arbitrarily large amounts of data from Cloud Spanner databases. BatchReadOnlyTransaction partitions a read/query request. Read/query request can then be executed independently over each partition while observing the same snapshot of the database. BatchReadOnlyTransaction can also be shared across multiple clients by passing around the BatchReadOnlyTransactionID and then recreating the transaction using Client.BatchReadOnlyTransactionFromID.

Note: if a client is used only to run partitions, you can create it using a ClientConfig with both MinOpened and MaxIdle set to zero to avoid creating unnecessary sessions. You can also avoid excess gRPC channels by setting ClientConfig.NumChannels to the number of concurrently active BatchReadOnlyTransactions you expect to have.

func (*BatchReadOnlyTransaction) AnalyzeQuery 

func (t *BatchReadOnlyTransaction) AnalyzeQuery(ctx context.Context, statement Statement) (*sppb.QueryPlan, error)

AnalyzeQuery returns the query plan for statement.

func (*BatchReadOnlyTransaction) Cleanup 

func (t *BatchReadOnlyTransaction) Cleanup(ctx context.Context)

Cleanup cleans up all the resources used by this transaction and makes it unusable. Once this method is invoked, the transaction is no longer usable anywhere, including other clients/processes with which this transaction was shared.

Calling Cleanup is optional, but recommended. If Cleanup is not called, the transaction's resources will be freed when the session expires on the backend and is deleted. For more information about recycled sessions, see https://cloud.google.com/spanner/docs/sessions.

func (*BatchReadOnlyTransaction) Close 

func (t *BatchReadOnlyTransaction) Close()

Close marks the txn as closed.

func (*BatchReadOnlyTransaction) Execute 

func (t *BatchReadOnlyTransaction) Execute(ctx context.Context, p *Partition) *RowIterator

Execute runs a single Partition obtained from PartitionRead or PartitionQuery.

func (*BatchReadOnlyTransaction) PartitionQuery 

func (t *BatchReadOnlyTransaction) PartitionQuery(ctx context.Context, statement Statement, opt PartitionOptions) ([]*Partition, error)

PartitionQuery returns a list of Partitions that can be used to execute a query against the database.

func (*BatchReadOnlyTransaction) PartitionQueryWithOptions added in v1.3.0 

func (t *BatchReadOnlyTransaction) PartitionQueryWithOptions(ctx context.Context, statement Statement, opt PartitionOptions, qOpts QueryOptions) ([]*Partition, error)

PartitionQueryWithOptions returns a list of Partitions that can be used to execute a query against the database. The sql query execution will be optimized based on the given query options.

func (*BatchReadOnlyTransaction) PartitionRead 

func (t *BatchReadOnlyTransaction) PartitionRead(ctx context.Context, table string, keys KeySet, columns []string, opt PartitionOptions) ([]*Partition, error)

PartitionRead returns a list of Partitions that can be used to read rows from the database. These partitions can be executed across multiple processes, even across different machines. The partition size and count hints can be configured using PartitionOptions.

func (*BatchReadOnlyTransaction) PartitionReadUsingIndex 

func (t *BatchReadOnlyTransaction) PartitionReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string, opt PartitionOptions) ([]*Partition, error)

PartitionReadUsingIndex returns a list of Partitions that can be used to read rows from the database using an index.

func (*BatchReadOnlyTransaction) PartitionReadUsingIndexWithOptions added in v1.22.0 

func (t *BatchReadOnlyTransaction) PartitionReadUsingIndexWithOptions(ctx context.Context, table, index string, keys KeySet, columns []string, opt PartitionOptions, readOptions ReadOptions) ([]*Partition, error)

PartitionReadUsingIndexWithOptions returns a list of Partitions that can be used to read rows from the database using an index. Pass a ReadOptions to modify the read operation.

func (*BatchReadOnlyTransaction) PartitionReadWithOptions added in v1.22.0 

func (t *BatchReadOnlyTransaction) PartitionReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opt PartitionOptions, readOptions ReadOptions) ([]*Partition, error)

PartitionReadWithOptions returns a list of Partitions that can be used to read rows from the database. These partitions can be executed across multiple processes, even across different machines. The partition size and count hints can be configured using PartitionOptions. Pass a ReadOptions to modify the read operation.

func (*BatchReadOnlyTransaction) Query 

func (t *BatchReadOnlyTransaction) Query(ctx context.Context, statement Statement) *RowIterator

Query executes a query against the database. It returns a RowIterator for retrieving the resulting rows.

Query returns only row data, without a query plan or execution statistics. Use QueryWithStats to get rows along with the plan and statistics. Use AnalyzeQuery to get just the plan.

func (*BatchReadOnlyTransaction) QueryWithOptions added in v1.3.0 

func (t *BatchReadOnlyTransaction) QueryWithOptions(ctx context.Context, statement Statement, opts QueryOptions) *RowIterator

QueryWithOptions executes a SQL statment against the database. It returns a RowIterator for retrieving the resulting rows. The sql query execution will be optimized based on the given query options.

func (*BatchReadOnlyTransaction) QueryWithStats 

func (t *BatchReadOnlyTransaction) QueryWithStats(ctx context.Context, statement Statement) *RowIterator

QueryWithStats executes a SQL statement against the database. It returns a RowIterator for retrieving the resulting rows. The RowIterator will also be populated with a query plan and execution statistics.

func (*BatchReadOnlyTransaction) Read 

func (t *BatchReadOnlyTransaction) Read(ctx context.Context, table string, keys KeySet, columns []string) *RowIterator

Read returns a RowIterator for reading multiple rows from the database.

func (*BatchReadOnlyTransaction) ReadRow 

func (t *BatchReadOnlyTransaction) ReadRow(ctx context.Context, table string, key Key, columns []string) (*Row, error)

ReadRow reads a single row from the database.

If no row is present with the given key, then ReadRow returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

func (*BatchReadOnlyTransaction) ReadRowUsingIndex added in v1.2.0 

func (t *BatchReadOnlyTransaction) ReadRowUsingIndex(ctx context.Context, table string, index string, key Key, columns []string) (*Row, error)

ReadRowUsingIndex reads a single row from the database using an index.

If no row is present with the given index, then ReadRowUsingIndex returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

If more than one row received with the given index, then ReadRowUsingIndex returns an error where spanner.ErrCode(err) is codes.FailedPrecondition.

func (*BatchReadOnlyTransaction) ReadRowWithOptions added in v1.29.0 

func (t *BatchReadOnlyTransaction) ReadRowWithOptions(ctx context.Context, table string, key Key, columns []string, opts *ReadOptions) (*Row, error)

ReadRowWithOptions reads a single row from the database. Pass a ReadOptions to modify the read operation.

If no row is present with the given key, then ReadRowWithOptions returns an error where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

func (*BatchReadOnlyTransaction) ReadUsingIndex 

func (t *BatchReadOnlyTransaction) ReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string) (ri *RowIterator)

ReadUsingIndex calls ReadWithOptions with ReadOptions{Index: index}.

func (*BatchReadOnlyTransaction) ReadWithOptions 

func (t *BatchReadOnlyTransaction) ReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opts *ReadOptions) (ri *RowIterator)

ReadWithOptions returns a RowIterator for reading multiple rows from the database. Pass a ReadOptions to modify the read operation.

type BatchReadOnlyTransactionID 

type BatchReadOnlyTransactionID struct {
	// contains filtered or unexported fields
}

BatchReadOnlyTransactionID is a unique identifier for a BatchReadOnlyTransaction. It can be used to re-create a BatchReadOnlyTransaction on a different machine or process by calling Client.BatchReadOnlyTransactionFromID.

func (BatchReadOnlyTransactionID) MarshalBinary 

func (tid BatchReadOnlyTransactionID) MarshalBinary() (data []byte, err error)

MarshalBinary implements BinaryMarshaler.

func (*BatchReadOnlyTransactionID) UnmarshalBinary 

func (tid *BatchReadOnlyTransactionID) UnmarshalBinary(data []byte) error

UnmarshalBinary implements BinaryUnmarshaler.

type BatchWriteOptions added in v1.52.0 

type BatchWriteOptions struct {
	// Priority is the RPC priority to use for this request.
	Priority sppb.RequestOptions_Priority

	// The transaction tag to use for this request.
	TransactionTag string

	// If excludeTxnFromChangeStreams == true, modifications from all transactions
	// in this batch write request will not be recorded in allowed tracking
	// change treams with DDL option allow_txn_exclusion=true.
	ExcludeTxnFromChangeStreams bool
}

BatchWriteOptions provides options for a BatchWriteRequest.

type BatchWriteResponseIterator added in v1.52.0 

type BatchWriteResponseIterator struct {
	// contains filtered or unexported fields
}

BatchWriteResponseIterator is an iterator over BatchWriteResponse structures returned from BatchWrite RPC.

func (*BatchWriteResponseIterator) Do added in v1.52.0 

func (r *BatchWriteResponseIterator) Do(f func(r *sppb.BatchWriteResponse) error) error

Do calls the provided function once in sequence for each item in the iteration. If the function returns a non-nil error, Do immediately returns that error.

If there are no items in the iterator, Do will return nil without calling the provided function.

Do always calls Stop on the iterator.

func (*BatchWriteResponseIterator) Next added in v1.52.0 

func (r *BatchWriteResponseIterator) Next() (*sppb.BatchWriteResponse, error)

Next returns the next result. Its second return value is iterator.Done if there are no more results. Once Next returns Done, all subsequent calls will return Done.

func (*BatchWriteResponseIterator) Stop added in v1.52.0 

func (r *BatchWriteResponseIterator) Stop()

Stop terminates the iteration. It should be called after you finish using the iterator.

type Client 

type Client struct {
	// contains filtered or unexported fields
}

Client is a client for reading and writing data to a Cloud Spanner database. A client is safe to use concurrently, except for its Close method.

func NewClient 

func NewClient(ctx context.Context, database string, opts ...option.ClientOption) (*Client, error)

NewClient creates a client to a database. A valid database name has the form projects/PROJECT_ID/instances/INSTANCE_ID/databases/DATABASE_ID. It uses a default configuration.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

func main() {
	ctx := context.Background()
	const myDB = "projects/my-project/instances/my-instance/database/my-db"
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	_ = client // TODO: Use client.
}

Output:

func NewClientWithConfig 

func NewClientWithConfig(ctx context.Context, database string, config ClientConfig, opts ...option.ClientOption) (c *Client, err error)

NewClientWithConfig creates a client to a database. A valid database name has the form projects/PROJECT_ID/instances/INSTANCE_ID/databases/DATABASE_ID.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

func main() {
	ctx := context.Background()
	const myDB = "projects/my-project/instances/my-instance/database/my-db"
	client, err := spanner.NewClientWithConfig(ctx, myDB, spanner.ClientConfig{
		NumChannels: 10,
	})
	if err != nil {
		// TODO: Handle error.
	}
	_ = client     // TODO: Use client.
	client.Close() // Close client when done.
}

Output:

func NewMultiEndpointClient added in v1.61.0 

func NewMultiEndpointClient(ctx context.Context, database string, gmeCfg *grpcgcp.GCPMultiEndpointOptions, opts ...option.ClientOption) (*Client, *grpcgcp.GCPMultiEndpoint, error)

NewMultiEndpointClient is the same as NewMultiEndpointClientWithConfig with the default client configuration.

A valid database name has the form projects/PROJECT_ID/instances/INSTANCE_ID/databases/DATABASE_ID.

func NewMultiEndpointClientWithConfig added in v1.61.0 

func NewMultiEndpointClientWithConfig(ctx context.Context, database string, config ClientConfig, gmeCfg *grpcgcp.GCPMultiEndpointOptions, opts ...option.ClientOption) (c *Client, gme *grpcgcp.GCPMultiEndpoint, err error)

NewMultiEndpointClientWithConfig creates a client to a database using GCPMultiEndpoint.

The purposes of GCPMultiEndpoint are:

  • Fallback to an alternative endpoint (host:port) when the original endpoint is completely unavailable.
  • Be able to route a Cloud Spanner call to a specific group of endpoints.
  • Be able to reconfigure endpoints in runtime.

The GRPCgcpConfig and DialFunc in the GCPMultiEndpointOptions are optional and will be configured automatically.

For GCPMultiEndpoint the number of channels is configured via MaxSize of the ChannelPool config in the GRPCgcpConfig.

The GCPMultiEndpoint returned can be used to update the endpoints in runtime.

A valid database name has the form projects/PROJECT_ID/instances/INSTANCE_ID/databases/DATABASE_ID.

func (*Client) Apply 

func (c *Client) Apply(ctx context.Context, ms []*Mutation, opts ...ApplyOption) (commitTimestamp time.Time, err error)

Apply applies a list of mutations atomically to the database.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	m := spanner.Update("Users", []string{"name", "email"}, []interface{}{"alice", "a@example.com"})
	_, err = client.Apply(ctx, []*spanner.Mutation{m})
	if err != nil {
		// TODO: Handle error.
	}
}

Output:

func (*Client) BatchReadOnlyTransaction 

func (c *Client) BatchReadOnlyTransaction(ctx context.Context, tb TimestampBound) (*BatchReadOnlyTransaction, error)

BatchReadOnlyTransaction returns a BatchReadOnlyTransaction that can be used for partitioned reads or queries from a snapshot of the database. This is useful in batch processing pipelines where one wants to divide the work of reading from the database across multiple machines.

Note: This transaction does not use the underlying session pool but creates a new session each time, and the session is reused across clients.

You should call Close() after the txn is no longer needed on local client, and call Cleanup() when the txn is finished for all clients, to free the session.

Example 
package main

import (
	"context"
	"sync"

	"cloud.google.com/go/spanner"
	"google.golang.org/api/iterator"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	var (
		client *spanner.Client
		txn    *spanner.BatchReadOnlyTransaction
		err    error
	)
	if client, err = spanner.NewClient(ctx, myDB); err != nil {
		// TODO: Handle error.
	}
	defer client.Close()
	if txn, err = client.BatchReadOnlyTransaction(ctx, spanner.StrongRead()); err != nil {
		// TODO: Handle error.
	}
	defer txn.Close()

	// Singer represents the elements in a row from the Singers table.
	type Singer struct {
		SingerID   int64
		FirstName  string
		LastName   string
		SingerInfo []byte
	}
	stmt := spanner.Statement{SQL: "SELECT * FROM Singers;"}
	partitions, err := txn.PartitionQuery(ctx, stmt, spanner.PartitionOptions{})
	if err != nil {
		// TODO: Handle error.
	}
	// Note: here we use multiple goroutines, but you should use separate
	// processes/machines.
	wg := sync.WaitGroup{}
	for i, p := range partitions {
		wg.Add(1)
		go func(i int, p *spanner.Partition) {
			defer wg.Done()
			iter := txn.Execute(ctx, p)
			defer iter.Stop()
			for {
				row, err := iter.Next()
				if err == iterator.Done {
					break
				} else if err != nil {
					// TODO: Handle error.
				}
				var s Singer
				if err := row.ToStruct(&s); err != nil {
					// TODO: Handle error.
				}
				_ = s // TODO: Process the row.
			}
		}(i, p)
	}
	wg.Wait()
}

Output:

func (*Client) BatchReadOnlyTransactionFromID 

func (c *Client) BatchReadOnlyTransactionFromID(tid BatchReadOnlyTransactionID) *BatchReadOnlyTransaction

BatchReadOnlyTransactionFromID reconstruct a BatchReadOnlyTransaction from BatchReadOnlyTransactionID

func (*Client) BatchWrite added in v1.52.0 

func (c *Client) BatchWrite(ctx context.Context, mgs []*MutationGroup) *BatchWriteResponseIterator

BatchWrite applies a list of mutation groups in a collection of efficient transactions. The mutation groups are applied non-atomically in an unspecified order and thus, they must be independent of each other. Partial failure is possible, i.e., some mutation groups may have been applied successfully, while some may have failed. The results of individual batches are streamed into the response as the batches are applied.

BatchWrite requests are not replay protected, meaning that each mutation group may be applied more than once. Replays of non-idempotent mutations may have undesirable effects. For example, replays of an insert mutation may produce an already exists error or if you use generated or commit timestamp-based keys, it may result in additional rows being added to the mutation's table. We recommend structuring your mutation groups to be idempotent to avoid this issue.

func (*Client) BatchWriteWithOptions added in v1.52.0 

func (c *Client) BatchWriteWithOptions(ctx context.Context, mgs []*MutationGroup, opts BatchWriteOptions) *BatchWriteResponseIterator

BatchWriteWithOptions is same as BatchWrite. It accepts additional options to customize the request.

func (*Client) ClientID added in v1.57.0 

func (c *Client) ClientID() string

ClientID returns the id of the Client. This is not recommended for customer applications and used internally for testing.

func (*Client) Close 

func (c *Client) Close()

Close closes the client.

func (*Client) DatabaseName added in v1.19.0 

func (c *Client) DatabaseName() string

DatabaseName returns the full name of a database, e.g., "projects/spanner-cloud-test/instances/foo/databases/foodb".

func (*Client) PartitionedUpdate 

func (c *Client) PartitionedUpdate(ctx context.Context, statement Statement) (count int64, err error)

PartitionedUpdate executes a DML statement in parallel across the database, using separate, internal transactions that commit independently. The DML statement must be fully partitionable: it must be expressible as the union of many statements each of which accesses only a single row of the table. The statement should also be idempotent, because it may be applied more than once.

PartitionedUpdate returns an estimated count of the number of rows affected. The actual number of affected rows may be greater than the estimate.

func (*Client) PartitionedUpdateWithOptions added in v1.3.0 

func (c *Client) PartitionedUpdateWithOptions(ctx context.Context, statement Statement, opts QueryOptions) (count int64, err error)

PartitionedUpdateWithOptions executes a DML statement in parallel across the database, using separate, internal transactions that commit independently. The sql query execution will be optimized based on the given query options.

func (*Client) ReadOnlyTransaction 

func (c *Client) ReadOnlyTransaction() *ReadOnlyTransaction

ReadOnlyTransaction returns a ReadOnlyTransaction that can be used for multiple reads from the database. You must call Close() when the ReadOnlyTransaction is no longer needed to release resources on the server.

ReadOnlyTransaction will use a strong TimestampBound by default. Use ReadOnlyTransaction.WithTimestampBound to specify a different TimestampBound. A non-strong bound can be used to reduce latency, or "time-travel" to prior versions of the database, see the documentation of TimestampBound for details.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	t := client.ReadOnlyTransaction()
	defer t.Close()
	// TODO: Read with t using Read, ReadRow, ReadUsingIndex, or Query.
}

Output:

func (*Client) ReadWriteTransaction 

func (c *Client) ReadWriteTransaction(ctx context.Context, f func(context.Context, *ReadWriteTransaction) error) (commitTimestamp time.Time, err error)

ReadWriteTransaction executes a read-write transaction, with retries as necessary.

The function f will be called one or more times. It must not maintain any state between calls.

If the transaction cannot be committed or if f returns an ABORTED error, ReadWriteTransaction will call f again. It will continue to call f until the transaction can be committed or the Context times out or is cancelled. If f returns an error other than ABORTED, ReadWriteTransaction will abort the transaction and return the error.

To limit the number of retries, set a deadline on the Context rather than using a fixed limit on the number of attempts. ReadWriteTransaction will retry as needed until that deadline is met.

See https://godoc.org/cloud.google.com/go/spanner#ReadWriteTransaction for more details.

Example 
package main

import (
	"context"
	"errors"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
		var balance int64
		row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
		if err != nil {
			// This function will be called again if this is an IsAborted error.
			return err
		}
		if err := row.Column(0, &balance); err != nil {
			return err
		}

		if balance <= 10 {
			return errors.New("insufficient funds in account")
		}
		balance -= 10
		m := spanner.Update("Accounts", []string{"user", "balance"}, []interface{}{"alice", balance})
		// The buffered mutation will be committed. If the commit fails with an
		// IsAborted error, this function will be called again.
		return txn.BufferWrite([]*spanner.Mutation{m})
	})
	if err != nil {
		// TODO: Handle error.
	}
}

Output:

func (*Client) ReadWriteTransactionWithOptions added in v1.12.0 

func (c *Client) ReadWriteTransactionWithOptions(ctx context.Context, f func(context.Context, *ReadWriteTransaction) error, options TransactionOptions) (resp CommitResponse, err error)

ReadWriteTransactionWithOptions executes a read-write transaction with configurable options, with retries as necessary.

ReadWriteTransactionWithOptions is a configurable ReadWriteTransaction.

See https://godoc.org/cloud.google.com/go/spanner#ReadWriteTransaction for more details.

func (*Client) Single 

func (c *Client) Single() *ReadOnlyTransaction

Single provides a read-only snapshot transaction optimized for the case where only a single read or query is needed. This is more efficient than using ReadOnlyTransaction() for a single read or query.

Single will use a strong TimestampBound by default. Use ReadOnlyTransaction.WithTimestampBound to specify a different TimestampBound. A non-strong bound can be used to reduce latency, or "time-travel" to prior versions of the database, see the documentation of TimestampBound for details.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	iter := client.Single().Query(ctx, spanner.NewStatement("SELECT FirstName FROM Singers"))
	_ = iter // TODO: iterate using Next or Do.
}

Output:

type ClientConfig 

type ClientConfig struct {
	// NumChannels is the number of gRPC channels.
	// If zero, a reasonable default is used based on the execution environment.
	//
	// Deprecated: The Spanner client now uses a pool of gRPC connections. Use
	// option.WithGRPCConnectionPool(numConns) instead to specify the number of
	// connections the client should use. The client will default to a
	// reasonable default if this option is not specified.
	NumChannels int

	// SessionPoolConfig is the configuration for session pool.
	SessionPoolConfig

	// SessionLabels for the sessions created by this client.
	// See https://cloud.google.com/spanner/docs/reference/rpc/google.spanner.v1#session
	// for more info.
	SessionLabels map[string]string

	// QueryOptions is the configuration for executing a sql query.
	QueryOptions QueryOptions

	// ReadOptions is the configuration for reading rows from a database
	ReadOptions ReadOptions

	// ApplyOptions is the configuration for applying
	ApplyOptions []ApplyOption

	// TransactionOptions is the configuration for a transaction.
	TransactionOptions TransactionOptions

	// BatchWriteOptions is the configuration for a BatchWrite request.
	BatchWriteOptions BatchWriteOptions

	// CallOptions is the configuration for providing custom retry settings that
	// override the default values.
	CallOptions *vkit.CallOptions

	// UserAgent is the prefix to the user agent header. This is used to supply information
	// such as application name or partner tool.
	//
	// Internal Use Only: This field is for internal tracking purpose only,
	// setting the value for this config is not required.
	//
	// Recommended format: “application-or-tool-ID/major.minor.version“.
	UserAgent string

	// DatabaseRole specifies the role to be assumed for all operations on the
	// database by this client.
	DatabaseRole string

	// DisableRouteToLeader specifies if all the requests of type read-write and PDML
	// need to be routed to the leader region.
	//
	// Default: false
	DisableRouteToLeader bool

	// Logger is the logger to use for this client. If it is nil, all logging
	// will be directed to the standard logger.
	Logger *log.Logger

	//
	// Sets the compression to use for all gRPC calls. The compressor must be a valid name.
	// This will enable compression both from the client to the
	// server and from the server to the client.
	//
	// Supported values are:
	//  gzip: Enable gzip compression
	//  identity: Disable compression
	//
	//  Default: identity
	Compression string

	// BatchTimeout specifies the timeout for a batch of sessions managed sessionClient.
	BatchTimeout time.Duration

	// ClientConfig options used to set the DirectedReadOptions for all ReadRequests
	// and ExecuteSqlRequests for the Client which indicate which replicas or regions
	// should be used for non-transactional reads or queries.
	DirectedReadOptions *sppb.DirectedReadOptions

	OpenTelemetryMeterProvider metric.MeterProvider
}

ClientConfig has configurations for the client.

type CommitOptions added in v1.14.0 

type CommitOptions struct {
	ReturnCommitStats bool
	MaxCommitDelay    *time.Duration
}

CommitOptions provides options for committing a transaction in a database.

type CommitResponse added in v1.12.0 

type CommitResponse struct {
	// CommitTs is the commit time for a transaction.
	CommitTs time.Time
	// CommitStats is the commit statistics for a transaction.
	CommitStats *sppb.CommitResponse_CommitStats
}

CommitResponse provides a response of a transaction commit in a database.

type DecodeOptions added in v1.56.0 

type DecodeOptions interface {
	Apply(s *decodeSetting)
}

DecodeOptions is the interface to change decode struct settings

func WithLenient added in v1.56.0 

func WithLenient() DecodeOptions

WithLenient returns a DecodeOptions that allows decoding into a struct with missing fields in database.

type Decoder added in v1.9.0 

type Decoder interface {
	DecodeSpanner(input interface{}) error
}

Decoder is the interface implemented by a custom type that can be decoded from a supported type by Spanner. A code example: 

type customField struct {
    Prefix string
    Suffix string
}

// Convert a string to a customField value
func (cf *customField) DecodeSpanner(val interface{}) (err error) {
    strVal, ok := val.(string)
    if !ok {
        return fmt.Errorf("failed to decode customField: %v", val)
    }
    s := strings.Split(strVal, "-")
    if len(s) > 1 {
        cf.Prefix = s[0]
        cf.Suffix = s[1]
    }
    return nil
}

type Encoder added in v1.9.0 

type Encoder interface {
	EncodeSpanner() (interface{}, error)
}

Encoder is the interface implemented by a custom type that can be encoded to a supported type by Spanner. A code example: 

type customField struct {
    Prefix string
    Suffix string
}

// Convert a customField value to a string
func (cf customField) EncodeSpanner() (interface{}, error) {
    var b bytes.Buffer
    b.WriteString(cf.Prefix)
    b.WriteString("-")
    b.WriteString(cf.Suffix)
    return b.String(), nil
}

type Error deprecated 

type Error struct {
	// Code is the canonical error code for describing the nature of a
	// particular error.
	//
	// Deprecated: The error code should be extracted from the wrapped error by
	// calling ErrCode(err error). This field will be removed in a future
	// release.
	Code codes.Code

	// Desc explains more details of the error.
	Desc string
	// contains filtered or unexported fields
}

Error is the structured error returned by Cloud Spanner client.

Deprecated: Unwrap any error that is returned by the Spanner client as an APIError to access the error details. Do not try to convert the error to the spanner.Error struct, as that struct may be removed in a future release.

Example: var apiErr *apierror.APIError _, err := spanner.NewClient(context.Background()) errors.As(err, &apiErr)

func (*Error) Error 

func (e *Error) Error() string

Error implements error.Error.

func (*Error) GRPCStatus 

func (e *Error) GRPCStatus() *status.Status

GRPCStatus returns the corresponding gRPC Status of this Spanner error. This allows the error to be converted to a gRPC status using `status.Convert(error)`.

func (*Error) Unwrap added in v1.2.0 

func (e *Error) Unwrap() error

Unwrap returns the wrapped error (if any).

type GenericColumnValue 

type GenericColumnValue struct {
	Type  *sppb.Type
	Value *proto3.Value
}

GenericColumnValue represents the generic encoded value and type of the column. See google.spanner.v1.ResultSet proto for details. This can be useful for proxying query results when the result types are not known in advance.

If you populate a GenericColumnValue from a row using Row.Column or related methods, do not modify the contents of Type and Value.

func (GenericColumnValue) Decode 

func (v GenericColumnValue) Decode(ptr interface{}) error

Decode decodes a GenericColumnValue. The ptr argument should be a pointer to a Go value that can accept v.

Example 
package main

import (
	"fmt"

	"cloud.google.com/go/spanner"
	sppb "cloud.google.com/go/spanner/apiv1/spannerpb"
)

func main() {
	// In real applications, rows can be retrieved by methods like client.Single().ReadRow().
	row, err := spanner.NewRow([]string{"intCol", "strCol"}, []interface{}{42, "my-text"})
	if err != nil {
		// TODO: Handle error.
	}
	for i := 0; i < row.Size(); i++ {
		var col spanner.GenericColumnValue
		if err := row.Column(i, &col); err != nil {
			// TODO: Handle error.
		}
		switch col.Type.Code {
		case sppb.TypeCode_INT64:
			var v int64
			if err := col.Decode(&v); err != nil {
				// TODO: Handle error.
			}
			fmt.Println("int", v)
		case sppb.TypeCode_STRING:
			var v string
			if err := col.Decode(&v); err != nil {
				// TODO: Handle error.
			}
			fmt.Println("string", v)
		}
	}
}

Output:

int 42
string my-text

type InactiveTransactionRemovalOptions added in v1.52.0 

type InactiveTransactionRemovalOptions struct {
	// ActionOnInactiveTransaction is the configuration to choose action for inactive transactions.
	// It can be one of Warn, Close, WarnAndClose.
	ActionOnInactiveTransaction ActionOnInactiveTransactionKind
	// contains filtered or unexported fields
}

InactiveTransactionRemovalOptions has configurations for action on long-running transactions.

type Key 

type Key []interface{}

A Key can be either a Cloud Spanner row's primary key or a secondary index key. It is essentially an interface{} array, which represents a set of Cloud Spanner columns. A Key can be used as:

  • A primary key which uniquely identifies a Cloud Spanner row.
  • A secondary index key which maps to a set of Cloud Spanner rows indexed under it.
  • An endpoint of primary key/secondary index ranges; see the KeyRange type.

Rows that are identified by the Key type are outputs of read operation or targets of delete operation in a mutation. Note that for Insert/Update/InsertOrUpdate/Update mutation types, although they don't require a primary key explicitly, the column list provided must contain enough columns that can comprise a primary key.

Keys are easy to construct. For example, suppose you have a table with a primary key of username and product ID. To make a key for this table: 

key := spanner.Key{"john", 16}

See the description of Row and Mutation types for how Go types are mapped to Cloud Spanner types. For convenience, Key type supports a wide range of Go types:

  • int, int8, int16, int32, int64, and NullInt64 are mapped to Cloud Spanner's INT64 type.
  • uint8, uint16 and uint32 are also mapped to Cloud Spanner's INT64 type.
  • float32, float64, NullFloat64 are mapped to Cloud Spanner's FLOAT64 type.
  • bool and NullBool are mapped to Cloud Spanner's BOOL type.
  • []byte is mapped to Cloud Spanner's BYTES type.
  • string and NullString are mapped to Cloud Spanner's STRING type.
  • time.Time and NullTime are mapped to Cloud Spanner's TIMESTAMP type.
  • civil.Date and NullDate are mapped to Cloud Spanner's DATE type.
  • protoreflect.Enum and NullProtoEnum are mapped to Cloud Spanner's ENUM type.

func (Key) AsPrefix 

func (key Key) AsPrefix() KeyRange

AsPrefix returns a KeyRange for all keys where k is the prefix.

func (Key) String 

func (key Key) String() string

String implements fmt.Stringer for Key. For string, []byte and NullString, it prints the uninterpreted bytes of their contents, leaving caller with the opportunity to escape the output.

type KeyRange 

type KeyRange struct {
	// Start specifies the left boundary of the key range; End specifies
	// the right boundary of the key range.
	Start, End Key

	// Kind describes whether the boundaries of the key range include
	// their keys.
	Kind KeyRangeKind
}

A KeyRange represents a range of rows in a table or index.

A range has a Start key and an End key. IncludeStart and IncludeEnd indicate whether the Start and End keys are included in the range.

For example, consider the following table definition: 

CREATE TABLE UserEvents (
  UserName STRING(MAX),
  EventDate STRING(10),
) PRIMARY KEY(UserName, EventDate);

The following keys name rows in this table: 

spanner.Key{"Bob", "2014-09-23"}
spanner.Key{"Alfred", "2015-06-12"}

Since the UserEvents table's PRIMARY KEY clause names two columns, each UserEvents key has two elements; the first is the UserName, and the second is the EventDate.

Key ranges with multiple components are interpreted lexicographically by component using the table or index key's declared sort order. For example, the following range returns all events for user "Bob" that occurred in the year 2015: 

spanner.KeyRange{
	Start: spanner.Key{"Bob", "2015-01-01"},
	End:   spanner.Key{"Bob", "2015-12-31"},
	Kind:  ClosedClosed,
}

Start and end keys can omit trailing key components. This affects the inclusion and exclusion of rows that exactly match the provided key components: if IncludeStart is true, then rows that exactly match the provided components of the Start key are included; if IncludeStart is false then rows that exactly match are not included. IncludeEnd and End key behave in the same fashion.

For example, the following range includes all events for "Bob" that occurred during and after the year 2000: 

spanner.KeyRange{
	Start: spanner.Key{"Bob", "2000-01-01"},
	End:   spanner.Key{"Bob"},
	Kind:  ClosedClosed,
}

The next example retrieves all events for "Bob": 

spanner.Key{"Bob"}.AsPrefix()

To retrieve events before the year 2000: 

spanner.KeyRange{
	Start: spanner.Key{"Bob"},
	End:   spanner.Key{"Bob", "2000-01-01"},
	Kind:  ClosedOpen,
}

Although we specified a Kind for this KeyRange, we didn't need to, because the default is ClosedOpen. In later examples we'll omit Kind if it is ClosedOpen.

The following range includes all rows in a table or under a index: 

spanner.AllKeys()

This range returns all users whose UserName begins with any character from A to C: 

spanner.KeyRange{
	Start: spanner.Key{"A"},
	End:   spanner.Key{"D"},
}

This range returns all users whose UserName begins with B: 

spanner.KeyRange{
	Start: spanner.Key{"B"},
	End:   spanner.Key{"C"},
}

Key ranges honor column sort order. For example, suppose a table is defined as follows: 

CREATE TABLE DescendingSortedTable {
  Key INT64,
  ...
) PRIMARY KEY(Key DESC);

The following range retrieves all rows with key values between 1 and 100 inclusive: 

spanner.KeyRange{
	Start: spanner.Key{100},
	End:   spanner.Key{1},
	Kind:  ClosedClosed,
}

Note that 100 is passed as the start, and 1 is passed as the end, because Key is a descending column in the schema.

func (KeyRange) String 

func (r KeyRange) String() string

String implements fmt.Stringer for KeyRange type.

type KeyRangeKind 

type KeyRangeKind int

KeyRangeKind describes the kind of interval represented by a KeyRange: whether it is open or closed on the left and right. 

const (
	// ClosedOpen is closed on the left and open on the right: the Start
	// key is included, the End key is excluded.
	ClosedOpen KeyRangeKind = iota

	// ClosedClosed is closed on the left and the right: both keys are included.
	ClosedClosed

	// OpenClosed is open on the left and closed on the right: the Start
	// key is excluded, the End key is included.
	OpenClosed

	// OpenOpen is open on the left and the right: neither key is included.
	OpenOpen
)

type KeySet 

type KeySet interface {
	// contains filtered or unexported methods
}

A KeySet defines a collection of Cloud Spanner keys and/or key ranges. All the keys are expected to be in the same table or index. The keys need not be sorted in any particular way.

An individual Key can act as a KeySet, as can a KeyRange. Use the KeySets function to create a KeySet consisting of multiple Keys and KeyRanges. To obtain an empty KeySet, call KeySets with no arguments.

If the same key is specified multiple times in the set (for example if two ranges, two keys, or a key and a range overlap), the Cloud Spanner backend behaves as if the key were only specified once.

func AllKeys 

func AllKeys() KeySet

AllKeys returns a KeySet that represents all Keys of a table or a index.

func KeySetFromKeys added in v1.11.0 

func KeySetFromKeys(keys ...Key) KeySet

KeySetFromKeys returns a KeySet containing the given slice of keys.

func KeySets 

func KeySets(keySets ...KeySet) KeySet

KeySets returns the union of the KeySets. If any of the KeySets is AllKeys, then the resulting KeySet will be equivalent to AllKeys.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
	"google.golang.org/api/iterator"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	// Get some rows from the Accounts table using a secondary index. In this case we get all users who are in Georgia.
	iter := client.Single().ReadUsingIndex(context.Background(), "Accounts", "idx_state", spanner.Key{"GA"}, []string{"state"})

	// Create a empty KeySet by calling the KeySets function with no parameters.
	ks := spanner.KeySets()

	// Loop the results of a previous query iterator.
	for {
		row, err := iter.Next()
		if err == iterator.Done {
			break
		} else if err != nil {
			// TODO: Handle error.
		}
		var id string
		err = row.ColumnByName("User", &id)
		if err != nil {
			// TODO: Handle error.
		}
		ks = spanner.KeySets(spanner.KeySets(spanner.Key{id}, ks))
	}

	_ = ks //TODO: Go use the KeySet in another query.

}

Output:

type LossOfPrecisionHandlingOption added in v1.25.0 

type LossOfPrecisionHandlingOption int

LossOfPrecisionHandlingOption describes the option to deal with loss of precision on numeric values. 

const (
	// NumericRound automatically rounds a numeric value that has a higher
	// precision than what is supported by Spanner, e.g., 0.1234567895 rounds
	// to 0.123456790.
	NumericRound LossOfPrecisionHandlingOption = iota
	// NumericError returns an error for numeric values that have a higher
	// precision than what is supported by Spanner. E.g. the client returns an
	// error if the application tries to insert the value 0.1234567895.
	NumericError
)
var LossOfPrecisionHandling LossOfPrecisionHandlingOption

LossOfPrecisionHandling configures how to deal with loss of precision on numeric values. The value of this configuration is global and will be used for all Spanner clients.

type Mutation 

type Mutation struct {
	// contains filtered or unexported fields
}

A Mutation describes a modification to one or more Cloud Spanner rows. The mutation represents an insert, update, delete, etc on a table.

Many mutations can be applied in a single atomic commit. For purposes of constraint checking (such as foreign key constraints), the operations can be viewed as applying in the same order as the mutations are provided (so that, e.g., a row and its logical "child" can be inserted in the same commit).

The Apply function applies series of mutations. For example, 

 m := spanner.Insert("User",
	 []string{"user_id", "profile"},
	 []interface{}{UserID, profile})
 _, err := client.Apply(ctx, []*spanner.Mutation{m})

inserts a new row into the User table. The primary key for the new row is UserID (presuming that "user_id" has been declared as the primary key of the "User" table).

To apply a series of mutations as part of an atomic read-modify-write operation, use ReadWriteTransaction.

Updating a row

Changing the values of columns in an existing row is very similar to inserting a new row: 

m := spanner.Update("User",
	[]string{"user_id", "profile"},
	[]interface{}{UserID, profile})
_, err := client.Apply(ctx, []*spanner.Mutation{m})

Deleting a row

To delete a row, use spanner.Delete: 

m := spanner.Delete("User", spanner.Key{UserId})
_, err := client.Apply(ctx, []*spanner.Mutation{m})

spanner.Delete accepts a KeySet, so you can also pass in a KeyRange, or use the spanner.KeySets function to build any combination of Keys and KeyRanges.

Note that deleting a row in a table may also delete rows from other tables if cascading deletes are specified in those tables' schemas. Delete does nothing if the named row does not exist (does not yield an error).

Deleting a field

To delete/clear a field within a row, use spanner.Update with the value nil: 

m := spanner.Update("User",
	[]string{"user_id", "profile"},
	[]interface{}{UserID, nil})
_, err := client.Apply(ctx, []*spanner.Mutation{m})

The valid Go types and their corresponding Cloud Spanner types that can be used in the Insert/Update/InsertOrUpdate functions are: 

string, *string, NullString - STRING
[]string, []*string, []NullString - STRING ARRAY
[]byte - BYTES
[][]byte - BYTES ARRAY
int, int64, *int64, NullInt64 - INT64
[]int, []int64, []*int64, []NullInt64 - INT64 ARRAY
bool, *bool, NullBool - BOOL
[]bool, []*bool, []NullBool - BOOL ARRAY
float64, *float64, NullFloat64 - FLOAT64
[]float64, []*float64, []NullFloat64 - FLOAT64 ARRAY
time.Time, *time.Time, NullTime - TIMESTAMP
[]time.Time, []*time.Time, []NullTime - TIMESTAMP ARRAY
Date, *Date, NullDate - DATE
[]Date, []*Date, []NullDate - DATE ARRAY
big.Rat, *big.Rat, NullNumeric - NUMERIC
[]big.Rat, []*big.Rat, []NullNumeric - NUMERIC ARRAY

To compare two Mutations for testing purposes, use reflect.DeepEqual.

func Delete 

func Delete(table string, ks KeySet) *Mutation

Delete removes the rows described by the KeySet from the table. It succeeds whether or not the keys were present.

Example 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	m := spanner.Delete("Users", spanner.Key{"alice"})
	_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}

Output:
Example (KeyRange) 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	m := spanner.Delete("Users", spanner.KeyRange{
		Start: spanner.Key{"alice"},
		End:   spanner.Key{"bob"},
		Kind:  spanner.ClosedClosed,
	})
	_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}

Output:

func Insert 

func Insert(table string, cols []string, vals []interface{}) *Mutation

Insert returns a Mutation to insert a row into a table. If the row already exists, the write or transaction fails with codes.AlreadyExists.

Example 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	m := spanner.Insert("Users", []string{"name", "email"}, []interface{}{"alice", "a@example.com"})
	_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}

Output:

func InsertMap 

func InsertMap(table string, in map[string]interface{}) *Mutation

InsertMap returns a Mutation to insert a row into a table, specified by a map of column name to value. If the row already exists, the write or transaction fails with codes.AlreadyExists.

Example 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	m := spanner.InsertMap("Users", map[string]interface{}{
		"name":  "alice",
		"email": "a@example.com",
	})
	_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}

Output:

func InsertOrUpdate 

func InsertOrUpdate(table string, cols []string, vals []interface{}) *Mutation

InsertOrUpdate returns a Mutation to insert a row into a table. If the row already exists, it updates it instead. Any column values not explicitly written are preserved.

For a similar example, See Update.

func InsertOrUpdateMap 

func InsertOrUpdateMap(table string, in map[string]interface{}) *Mutation

InsertOrUpdateMap returns a Mutation to insert a row into a table, specified by a map of column to value. If the row already exists, it updates it instead. Any column values not explicitly written are preserved.

For a similar example, See UpdateMap.

func InsertOrUpdateStruct 

func InsertOrUpdateStruct(table string, in interface{}) (*Mutation, error)

InsertOrUpdateStruct returns a Mutation to insert a row into a table, specified by a Go struct. If the row already exists, it updates it instead. Any column values not explicitly written are preserved.

The in argument must be a struct or a pointer to a struct. Its exported fields specify the column names and values. Use a field tag like `spanner:"name"` to provide an alternative column name, or use `spanner:"-"` to ignore the field.

For a similar example, See UpdateStruct.

func InsertStruct 

func InsertStruct(table string, in interface{}) (*Mutation, error)

InsertStruct returns a Mutation to insert a row into a table, specified by a Go struct. If the row already exists, the write or transaction fails with codes.AlreadyExists.

The in argument must be a struct or a pointer to a struct. Its exported fields specify the column names and values. Use a field tag like `spanner:"name"` to provide an alternative column name, or use `spanner:"-"` to ignore the field.

Example 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	type User struct {
		Name, Email string
	}
	u := User{Name: "alice", Email: "a@example.com"}
	m, err := spanner.InsertStruct("Users", u)
	if err != nil {
		// TODO: Handle error.
	}
	_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}

Output:

func Replace 

func Replace(table string, cols []string, vals []interface{}) *Mutation

Replace returns a Mutation to insert a row into a table, deleting any existing row. Unlike InsertOrUpdate, this means any values not explicitly written become NULL.

For a similar example, See Update.

func ReplaceMap 

func ReplaceMap(table string, in map[string]interface{}) *Mutation

ReplaceMap returns a Mutation to insert a row into a table, deleting any existing row. Unlike InsertOrUpdateMap, this means any values not explicitly written become NULL. The row is specified by a map of column to value.

For a similar example, See UpdateMap.

func ReplaceStruct 

func ReplaceStruct(table string, in interface{}) (*Mutation, error)

ReplaceStruct returns a Mutation to insert a row into a table, deleting any existing row. Unlike InsertOrUpdateMap, this means any values not explicitly written become NULL. The row is specified by a Go struct.

The in argument must be a struct or a pointer to a struct. Its exported fields specify the column names and values. Use a field tag like `spanner:"name"` to provide an alternative column name, or use `spanner:"-"` to ignore the field.

For a similar example, See UpdateStruct.

func Update 

func Update(table string, cols []string, vals []interface{}) *Mutation

Update returns a Mutation to update a row in a table. If the row does not already exist, the write or transaction fails.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
		row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
		if err != nil {
			return err
		}
		var balance int64
		if err := row.Column(0, &balance); err != nil {
			return err
		}
		return txn.BufferWrite([]*spanner.Mutation{
			spanner.Update("Accounts", []string{"user", "balance"}, []interface{}{"alice", balance + 10}),
		})
	})
	if err != nil {
		// TODO: Handle error.
	}
}

Output:

func UpdateMap 

func UpdateMap(table string, in map[string]interface{}) *Mutation

UpdateMap returns a Mutation to update a row in a table, specified by a map of column to value. If the row does not already exist, the write or transaction fails.

Example

This example is the same as the one for Update, except for the use of UpdateMap. 

package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
		row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
		if err != nil {
			return err
		}
		var balance int64
		if err := row.Column(0, &balance); err != nil {
			return err
		}
		return txn.BufferWrite([]*spanner.Mutation{
			spanner.UpdateMap("Accounts", map[string]interface{}{
				"user":    "alice",
				"balance": balance + 10,
			}),
		})
	})
	if err != nil {
		// TODO: Handle error.
	}
}

Output:

func UpdateStruct 

func UpdateStruct(table string, in interface{}) (*Mutation, error)

UpdateStruct returns a Mutation to update a row in a table, specified by a Go struct. If the row does not already exist, the write or transaction fails.

Example

This example is the same as the one for Update, except for the use of UpdateStruct. 

package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	type account struct {
		User    string `spanner:"user"`
		Balance int64  `spanner:"balance"`
	}
	_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
		row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
		if err != nil {
			return err
		}
		var balance int64
		if err := row.Column(0, &balance); err != nil {
			return err
		}
		m, err := spanner.UpdateStruct("Accounts", account{
			User:    "alice",
			Balance: balance + 10,
		})
		if err != nil {
			return err
		}
		return txn.BufferWrite([]*spanner.Mutation{m})
	})
	if err != nil {
		// TODO: Handle error.
	}
}

Output:

type MutationGroup added in v1.52.0 

type MutationGroup struct {
	// The Mutations in this group
	Mutations []*Mutation
}

A MutationGroup is a list of Mutation to be committed atomically.

type NullBool 

type NullBool struct {
	Bool  bool // Bool contains the value when it is non-NULL, and false when NULL.
	Valid bool // Valid is true if Bool is not NULL.
}

NullBool represents a Cloud Spanner BOOL that may be NULL.

func (NullBool) GormDataType added in v1.27.0 

func (n NullBool) GormDataType() string

GormDataType is used by gorm to determine the default data type for fields with this type.

func (NullBool) IsNull added in v1.1.0 

func (n NullBool) IsNull() bool

IsNull implements NullableValue.IsNull for NullBool.

func (NullBool) MarshalJSON added in v1.3.0 

func (n NullBool) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullBool.

func (*NullBool) Scan added in v1.27.0 

func (n *NullBool) Scan(value interface{}) error

Scan implements the sql.Scanner interface.

func (NullBool) String 

func (n NullBool) String() string

String implements Stringer.String for NullBool

func (*NullBool) UnmarshalJSON added in v1.3.0 

func (n *NullBool) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullBool.

func (NullBool) Value added in v1.27.0 

func (n NullBool) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type NullDate 

type NullDate struct {
	Date  civil.Date // Date contains the value when it is non-NULL, and a zero civil.Date when NULL.
	Valid bool       // Valid is true if Date is not NULL.
}

NullDate represents a Cloud Spanner DATE that may be null.

func (NullDate) GormDataType added in v1.27.0 

func (n NullDate) GormDataType() string

GormDataType is used by gorm to determine the default data type for fields with this type.

func (NullDate) IsNull added in v1.1.0 

func (n NullDate) IsNull() bool

IsNull implements NullableValue.IsNull for NullDate.

func (NullDate) MarshalJSON added in v1.3.0 

func (n NullDate) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullDate.

func (*NullDate) Scan added in v1.27.0 

func (n *NullDate) Scan(value interface{}) error

Scan implements the sql.Scanner interface.

func (NullDate) String 

func (n NullDate) String() string

String implements Stringer.String for NullDate

func (*NullDate) UnmarshalJSON added in v1.3.0 

func (n *NullDate) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullDate.

func (NullDate) Value added in v1.27.0 

func (n NullDate) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type NullFloat32 added in v1.59.0 

type NullFloat32 struct {
	Float32 float32 // Float32 contains the value when it is non-NULL, and zero when NULL.
	Valid   bool    // Valid is true if FLOAT32 is not NULL.
}

NullFloat32 represents a Cloud Spanner FLOAT32 that may be NULL.

func (NullFloat32) GormDataType added in v1.59.0 

func (n NullFloat32) GormDataType() string

GormDataType is used by gorm to determine the default data type for fields with this type.

func (NullFloat32) IsNull added in v1.59.0 

func (n NullFloat32) IsNull() bool

IsNull implements NullableValue.IsNull for NullFloat32.

func (NullFloat32) MarshalJSON added in v1.59.0 

func (n NullFloat32) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullFloat32.

func (*NullFloat32) Scan added in v1.59.0 

func (n *NullFloat32) Scan(value interface{}) error

Scan implements the sql.Scanner interface.

func (NullFloat32) String added in v1.59.0 

func (n NullFloat32) String() string

String implements Stringer.String for NullFloat32

func (*NullFloat32) UnmarshalJSON added in v1.59.0 

func (n *NullFloat32) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullFloat32.

func (NullFloat32) Value added in v1.59.0 

func (n NullFloat32) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type NullFloat64 

type NullFloat64 struct {
	Float64 float64 // Float64 contains the value when it is non-NULL, and zero when NULL.
	Valid   bool    // Valid is true if Float64 is not NULL.
}

NullFloat64 represents a Cloud Spanner FLOAT64 that may be NULL.

func (NullFloat64) GormDataType added in v1.27.0 

func (n NullFloat64) GormDataType() string

GormDataType is used by gorm to determine the default data type for fields with this type.

func (NullFloat64) IsNull added in v1.1.0 

func (n NullFloat64) IsNull() bool

IsNull implements NullableValue.IsNull for NullFloat64.

func (NullFloat64) MarshalJSON added in v1.3.0 

func (n NullFloat64) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullFloat64.

func (*NullFloat64) Scan added in v1.27.0 

func (n *NullFloat64) Scan(value interface{}) error

Scan implements the sql.Scanner interface.

func (NullFloat64) String 

func (n NullFloat64) String() string

String implements Stringer.String for NullFloat64

func (*NullFloat64) UnmarshalJSON added in v1.3.0 

func (n *NullFloat64) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullFloat64.

func (NullFloat64) Value added in v1.27.0 

func (n NullFloat64) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type NullInt64 

type NullInt64 struct {
	Int64 int64 // Int64 contains the value when it is non-NULL, and zero when NULL.
	Valid bool  // Valid is true if Int64 is not NULL.
}

NullInt64 represents a Cloud Spanner INT64 that may be NULL.

func (NullInt64) GormDataType added in v1.27.0 

func (n NullInt64) GormDataType() string

GormDataType is used by gorm to determine the default data type for fields with this type.

func (NullInt64) IsNull added in v1.1.0 

func (n NullInt64) IsNull() bool

IsNull implements NullableValue.IsNull for NullInt64.

func (NullInt64) MarshalJSON added in v1.3.0 

func (n NullInt64) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullInt64.

func (*NullInt64) Scan added in v1.27.0 

func (n *NullInt64) Scan(value interface{}) error

Scan implements the sql.Scanner interface.

func (NullInt64) String 

func (n NullInt64) String() string

String implements Stringer.String for NullInt64

func (*NullInt64) UnmarshalJSON added in v1.3.0 

func (n *NullInt64) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullInt64.

func (NullInt64) Value added in v1.27.0 

func (n NullInt64) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type NullJSON added in v1.25.0 

type NullJSON struct {
	Value interface{} // Val contains the value when it is non-NULL, and nil when NULL.
	Valid bool        // Valid is true if Json is not NULL.
}

NullJSON represents a Cloud Spanner JSON that may be NULL.

This type must always be used when encoding values to a JSON column in Cloud Spanner.

NullJSON does not implement the driver.Valuer and sql.Scanner interfaces, as the underlying value can be anything. This means that the type NullJSON must also be used when calling sql.Row#Scan(dest ...interface{}) for a JSON column.

func (NullJSON) GormDataType added in v1.27.0 

func (n NullJSON) GormDataType() string

GormDataType is used by gorm to determine the default data type for fields with this type.

func (NullJSON) IsNull added in v1.25.0 

func (n NullJSON) IsNull() bool

IsNull implements NullableValue.IsNull for NullJSON.

func (NullJSON) MarshalJSON added in v1.25.0 

func (n NullJSON) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullJSON.

func (NullJSON) String added in v1.25.0 

func (n NullJSON) String() string

String implements Stringer.String for NullJSON.

func (*NullJSON) UnmarshalJSON added in v1.25.0 

func (n *NullJSON) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullJSON.

type NullNumeric added in v1.10.0 

type NullNumeric struct {
	Numeric big.Rat // Numeric contains the value when it is non-NULL, and a zero big.Rat when NULL.
	Valid   bool    // Valid is true if Numeric is not NULL.
}

NullNumeric represents a Cloud Spanner Numeric that may be NULL.

func (NullNumeric) GormDataType added in v1.27.0 

func (n NullNumeric) GormDataType() string

GormDataType is used by gorm to determine the default data type for fields with this type.

func (NullNumeric) IsNull added in v1.10.0 

func (n NullNumeric) IsNull() bool

IsNull implements NullableValue.IsNull for NullNumeric.

func (NullNumeric) MarshalJSON added in v1.10.0 

func (n NullNumeric) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullNumeric.

func (*NullNumeric) Scan added in v1.27.0 

func (n *NullNumeric) Scan(value interface{}) error

Scan implements the sql.Scanner interface.

func (NullNumeric) String added in v1.10.0 

func (n NullNumeric) String() string

String implements Stringer.String for NullNumeric

func (*NullNumeric) UnmarshalJSON added in v1.10.0 

func (n *NullNumeric) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullNumeric.

func (NullNumeric) Value added in v1.27.0 

func (n NullNumeric) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type NullProtoEnum added in v1.62.0 

type NullProtoEnum struct {
	ProtoEnumVal protoreflect.Enum // ProtoEnumVal contains the value when Valid is true, and nil when NULL.
	Valid        bool              // Valid is true if ProtoEnumVal is not NULL.
}

NullProtoEnum represents a Cloud Spanner ENUM that may be NULL. To write a NULL value using NullProtoEnum set ProtoEnumVal to typed nil and set Valid to true.

func (NullProtoEnum) IsNull added in v1.62.0 

func (n NullProtoEnum) IsNull() bool

IsNull implements NullableValue.IsNull for NullProtoEnum.

func (NullProtoEnum) MarshalJSON added in v1.62.0 

func (n NullProtoEnum) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullProtoEnum.

func (NullProtoEnum) String added in v1.62.0 

func (n NullProtoEnum) String() string

String implements Stringer.String for NullProtoEnum.

func (*NullProtoEnum) UnmarshalJSON added in v1.62.0 

func (n *NullProtoEnum) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullProtoEnum.

type NullProtoMessage added in v1.62.0 

type NullProtoMessage struct {
	ProtoMessageVal proto.Message // ProtoMessageVal contains the value when Valid is true, and nil when NULL.
	Valid           bool          // Valid is true if ProtoMessageVal is not NULL.
}

NullProtoMessage represents a Cloud Spanner PROTO that may be NULL. To write a NULL value using NullProtoMessage set ProtoMessageVal to typed nil and set Valid to true.

func (NullProtoMessage) IsNull added in v1.62.0 

func (n NullProtoMessage) IsNull() bool

IsNull implements NullableValue.IsNull for NullProtoMessage.

func (NullProtoMessage) MarshalJSON added in v1.62.0 

func (n NullProtoMessage) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullProtoMessage.

func (NullProtoMessage) String added in v1.62.0 

func (n NullProtoMessage) String() string

String implements Stringer.String for NullProtoMessage.

func (*NullProtoMessage) UnmarshalJSON added in v1.62.0 

func (n *NullProtoMessage) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullProtoMessage.

type NullRow 

type NullRow struct {
	Row   Row  // Row contains the value when it is non-NULL, and a zero Row when NULL.
	Valid bool // Valid is true if Row is not NULL.
}

NullRow represents a Cloud Spanner STRUCT that may be NULL. See also the document for Row. Note that NullRow is not a valid Cloud Spanner column Type.

type NullString 

type NullString struct {
	StringVal string // StringVal contains the value when it is non-NULL, and an empty string when NULL.
	Valid     bool   // Valid is true if StringVal is not NULL.
}

NullString represents a Cloud Spanner STRING that may be NULL.

func (NullString) GormDataType added in v1.27.0 

func (n NullString) GormDataType() string

GormDataType is used by gorm to determine the default data type for fields with this type.

func (NullString) IsNull added in v1.1.0 

func (n NullString) IsNull() bool

IsNull implements NullableValue.IsNull for NullString.

func (NullString) MarshalJSON added in v1.3.0 

func (n NullString) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullString.

func (*NullString) Scan added in v1.27.0 

func (n *NullString) Scan(value interface{}) error

Scan implements the sql.Scanner interface.

func (NullString) String 

func (n NullString) String() string

String implements Stringer.String for NullString

func (*NullString) UnmarshalJSON added in v1.3.0 

func (n *NullString) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullString.

func (NullString) Value added in v1.27.0 

func (n NullString) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type NullTime 

type NullTime struct {
	Time  time.Time // Time contains the value when it is non-NULL, and a zero time.Time when NULL.
	Valid bool      // Valid is true if Time is not NULL.
}

NullTime represents a Cloud Spanner TIMESTAMP that may be null.

func (NullTime) GormDataType added in v1.27.0 

func (n NullTime) GormDataType() string

GormDataType is used by gorm to determine the default data type for fields with this type.

func (NullTime) IsNull added in v1.1.0 

func (n NullTime) IsNull() bool

IsNull implements NullableValue.IsNull for NullTime.

func (NullTime) MarshalJSON added in v1.3.0 

func (n NullTime) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for NullTime.

func (*NullTime) Scan added in v1.27.0 

func (n *NullTime) Scan(value interface{}) error

Scan implements the sql.Scanner interface.

func (NullTime) String 

func (n NullTime) String() string

String implements Stringer.String for NullTime

func (*NullTime) UnmarshalJSON added in v1.3.0 

func (n *NullTime) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullTime.

func (NullTime) Value added in v1.27.0 

func (n NullTime) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type NullableValue added in v1.1.0 

type NullableValue interface {
	// IsNull returns true if the underlying database value is null.
	IsNull() bool
}

NullableValue is the interface implemented by all null value wrapper types.

type PGJsonB added in v1.40.0 

type PGJsonB struct {
	Value interface{} // Val contains the value when it is non-NULL, and nil when NULL.
	Valid bool        // Valid is true if PGJsonB is not NULL.
	// contains filtered or unexported fields
}

PGJsonB represents a Cloud Spanner PGJsonB that may be NULL.

func (PGJsonB) IsNull added in v1.40.0 

func (n PGJsonB) IsNull() bool

IsNull implements NullableValue.IsNull for PGJsonB.

func (PGJsonB) MarshalJSON added in v1.40.0 

func (n PGJsonB) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for PGJsonB.

func (PGJsonB) String added in v1.40.0 

func (n PGJsonB) String() string

String implements Stringer.String for PGJsonB.

func (*PGJsonB) UnmarshalJSON added in v1.40.0 

func (n *PGJsonB) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for PGJsonB.

type PGNumeric added in v1.30.0 

type PGNumeric struct {
	Numeric string // Numeric contains the value when it is non-NULL, and an empty string when NULL.
	Valid   bool   // Valid is true if Numeric is not NULL.
}

PGNumeric represents a Cloud Spanner PG Numeric that may be NULL.

func (PGNumeric) IsNull added in v1.30.0 

func (n PGNumeric) IsNull() bool

IsNull implements NullableValue.IsNull for PGNumeric.

func (PGNumeric) MarshalJSON added in v1.30.0 

func (n PGNumeric) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.MarshalJSON for PGNumeric.

func (PGNumeric) String added in v1.30.0 

func (n PGNumeric) String() string

String implements Stringer.String for PGNumeric

func (*PGNumeric) UnmarshalJSON added in v1.30.0 

func (n *PGNumeric) UnmarshalJSON(payload []byte) error

UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for PGNumeric.

type Partition 

type Partition struct {
	// contains filtered or unexported fields
}

Partition defines a segment of data to be read in a batch read or query. A partition can be serialized and processed across several different machines or processes.

func (*Partition) GetPartitionToken added in v1.52.0 

func (p *Partition) GetPartitionToken() []byte

GetPartitionToken returns partition token

func (Partition) MarshalBinary 

func (p Partition) MarshalBinary() (data []byte, err error)

MarshalBinary implements BinaryMarshaler.

func (*Partition) UnmarshalBinary 

func (p *Partition) UnmarshalBinary(data []byte) error

UnmarshalBinary implements BinaryUnmarshaler.

type PartitionOptions 

type PartitionOptions struct {
	// The desired data size for each partition generated.
	PartitionBytes int64
	// The desired maximum number of partitions to return.
	MaxPartitions int64
}

PartitionOptions specifies options for a PartitionQueryRequest and PartitionReadRequest. See https://godoc.org/google.golang.org/genproto/googleapis/spanner/v1#PartitionOptions for more details.

type QueryOptions added in v1.3.0 

type QueryOptions struct {
	Mode    *sppb.ExecuteSqlRequest_QueryMode
	Options *sppb.ExecuteSqlRequest_QueryOptions

	// Priority is the RPC priority to use for the query/update.
	Priority sppb.RequestOptions_Priority

	// The request tag to use for this request.
	RequestTag string

	// If this is for a partitioned query and DataBoostEnabled field is set to true, the request will be executed
	// via Spanner independent compute resources. Setting this option for regular query operations has no effect.
	DataBoostEnabled bool

	// QueryOptions option used to set the DirectedReadOptions for all ExecuteSqlRequests which indicate
	// which replicas or regions should be used for executing queries.
	DirectedReadOptions *sppb.DirectedReadOptions

	// Controls whether to exclude recording modifications in current partitioned update operation
	// from the allowed tracking change streams(with DDL option allow_txn_exclusion=true). Setting
	// this value for any sql/dml requests other than partitioned udpate will receive an error.
	ExcludeTxnFromChangeStreams bool
}

QueryOptions provides options for executing a sql query or update statement.

type ReadOnlyTransaction 

type ReadOnlyTransaction struct {
	// contains filtered or unexported fields
}

ReadOnlyTransaction provides a snapshot transaction with guaranteed consistency across reads, but does not allow writes. Read-only transactions can be configured to read at timestamps in the past.

Read-only transactions do not take locks. Instead, they work by choosing a Cloud Spanner timestamp, then executing all reads at that timestamp. Since they do not acquire locks, they do not block concurrent read-write transactions.

Unlike locking read-write transactions, read-only transactions never abort. They can fail if the chosen read timestamp is garbage collected; however, the default garbage collection policy is generous enough that most applications do not need to worry about this in practice. See the documentation of TimestampBound for more details.

A ReadOnlyTransaction consumes resources on the server until Close is called.

func (*ReadOnlyTransaction) AnalyzeQuery 

func (t *ReadOnlyTransaction) AnalyzeQuery(ctx context.Context, statement Statement) (*sppb.QueryPlan, error)

AnalyzeQuery returns the query plan for statement.

func (*ReadOnlyTransaction) Close 

func (t *ReadOnlyTransaction) Close()

Close closes a ReadOnlyTransaction, the transaction cannot perform any reads after being closed.

func (*ReadOnlyTransaction) Query 

func (t *ReadOnlyTransaction) Query(ctx context.Context, statement Statement) *RowIterator

Query executes a query against the database. It returns a RowIterator for retrieving the resulting rows.

Query returns only row data, without a query plan or execution statistics. Use QueryWithStats to get rows along with the plan and statistics. Use AnalyzeQuery to get just the plan.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	iter := client.Single().Query(ctx, spanner.NewStatement("SELECT FirstName FROM Singers"))
	_ = iter // TODO: iterate using Next or Do.
}

Output:

func (*ReadOnlyTransaction) QueryWithOptions added in v1.3.0 

func (t *ReadOnlyTransaction) QueryWithOptions(ctx context.Context, statement Statement, opts QueryOptions) *RowIterator

QueryWithOptions executes a SQL statment against the database. It returns a RowIterator for retrieving the resulting rows. The sql query execution will be optimized based on the given query options.

func (*ReadOnlyTransaction) QueryWithStats 

func (t *ReadOnlyTransaction) QueryWithStats(ctx context.Context, statement Statement) *RowIterator

QueryWithStats executes a SQL statement against the database. It returns a RowIterator for retrieving the resulting rows. The RowIterator will also be populated with a query plan and execution statistics.

func (*ReadOnlyTransaction) Read 

func (t *ReadOnlyTransaction) Read(ctx context.Context, table string, keys KeySet, columns []string) *RowIterator

Read returns a RowIterator for reading multiple rows from the database.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	iter := client.Single().Read(ctx, "Users",
		spanner.KeySets(spanner.Key{"alice"}, spanner.Key{"bob"}),
		[]string{"name", "email"})
	_ = iter // TODO: iterate using Next or Do.
}

Output:

func (*ReadOnlyTransaction) ReadRow 

func (t *ReadOnlyTransaction) ReadRow(ctx context.Context, table string, key Key, columns []string) (*Row, error)

ReadRow reads a single row from the database.

If no row is present with the given key, then ReadRow returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}
Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	row, err := client.Single().ReadRow(ctx, "Users", spanner.Key{"alice"},
		[]string{"name", "email"})
	if err != nil {
		// TODO: Handle error.
	}
	_ = row // TODO: use row
}

Output:

func (*ReadOnlyTransaction) ReadRowUsingIndex added in v1.2.0 

func (t *ReadOnlyTransaction) ReadRowUsingIndex(ctx context.Context, table string, index string, key Key, columns []string) (*Row, error)

ReadRowUsingIndex reads a single row from the database using an index.

If no row is present with the given index, then ReadRowUsingIndex returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

If more than one row received with the given index, then ReadRowUsingIndex returns an error where spanner.ErrCode(err) is codes.FailedPrecondition.

func (*ReadOnlyTransaction) ReadRowWithOptions added in v1.29.0 

func (t *ReadOnlyTransaction) ReadRowWithOptions(ctx context.Context, table string, key Key, columns []string, opts *ReadOptions) (*Row, error)

ReadRowWithOptions reads a single row from the database. Pass a ReadOptions to modify the read operation.

If no row is present with the given key, then ReadRowWithOptions returns an error where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

func (*ReadOnlyTransaction) ReadUsingIndex 

func (t *ReadOnlyTransaction) ReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string) (ri *RowIterator)

ReadUsingIndex calls ReadWithOptions with ReadOptions{Index: index}.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	iter := client.Single().ReadUsingIndex(ctx, "Users",
		"UsersByEmail",
		spanner.KeySets(spanner.Key{"a@example.com"}, spanner.Key{"b@example.com"}),
		[]string{"name", "email"})
	_ = iter // TODO: iterate using Next or Do.
}

Output:

func (*ReadOnlyTransaction) ReadWithOptions 

func (t *ReadOnlyTransaction) ReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opts *ReadOptions) (ri *RowIterator)

ReadWithOptions returns a RowIterator for reading multiple rows from the database. Pass a ReadOptions to modify the read operation.

Example 
package main

import (
	"context"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	// Use an index, and limit to 100 rows at most.
	iter := client.Single().ReadWithOptions(ctx, "Users",
		spanner.KeySets(spanner.Key{"a@example.com"}, spanner.Key{"b@example.com"}),
		[]string{"name", "email"}, &spanner.ReadOptions{
			Index: "UsersByEmail",
			Limit: 100,
		})
	_ = iter // TODO: iterate using Next or Do.
}

Output:

func (*ReadOnlyTransaction) Timestamp 

func (t *ReadOnlyTransaction) Timestamp() (time.Time, error)

Timestamp returns the timestamp chosen to perform reads and queries in this transaction. The value can only be read after some read or query has either returned some data or completed without returning any data.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	txn := client.Single()
	row, err := txn.ReadRow(ctx, "Users", spanner.Key{"alice"},
		[]string{"name", "email"})
	if err != nil {
		// TODO: Handle error.
	}
	readTimestamp, err := txn.Timestamp()
	if err != nil {
		// TODO: Handle error.
	}
	fmt.Println("read happened at", readTimestamp)
	_ = row // TODO: use row
}

Output:

func (*ReadOnlyTransaction) WithTimestampBound 

func (t *ReadOnlyTransaction) WithTimestampBound(tb TimestampBound) *ReadOnlyTransaction

WithTimestampBound specifies the TimestampBound to use for read or query. This can only be used before the first read or query is invoked. Note: bounded staleness is not available with general ReadOnlyTransactions; use a single-use ReadOnlyTransaction instead.

The returned value is the ReadOnlyTransaction so calls can be chained.

Example 
package main

import (
	"context"
	"fmt"
	"time"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	txn := client.Single().WithTimestampBound(spanner.MaxStaleness(30 * time.Second))
	row, err := txn.ReadRow(ctx, "Users", spanner.Key{"alice"}, []string{"name", "email"})
	if err != nil {
		// TODO: Handle error.
	}
	_ = row // TODO: use row
	readTimestamp, err := txn.Timestamp()
	if err != nil {
		// TODO: Handle error.
	}
	fmt.Println("read happened at", readTimestamp)
}

Output:

type ReadOptions 

type ReadOptions struct {
	// The index to use for reading. If non-empty, you can only read columns
	// that are part of the index key, part of the primary key, or stored in the
	// index due to a STORING clause in the index definition.
	Index string

	// The maximum number of rows to read. A limit value less than 1 means no
	// limit.
	Limit int

	// Priority is the RPC priority to use for the operation.
	Priority sppb.RequestOptions_Priority

	// The request tag to use for this request.
	RequestTag string

	// If this is for a partitioned read and DataBoostEnabled field is set to true, the request will be executed
	// via Spanner independent compute resources. Setting this option for regular read operations has no effect.
	DataBoostEnabled bool

	// ReadOptions option used to set the DirectedReadOptions for all ReadRequests which indicate
	// which replicas or regions should be used for running read operations.
	DirectedReadOptions *sppb.DirectedReadOptions

	// An option to control the order in which rows are returned from a read.
	OrderBy sppb.ReadRequest_OrderBy

	// A lock hint mechanism to use for this request. This setting is only applicable for
	// read-write transaction as as read-only transactions do not take locks.
	LockHint sppb.ReadRequest_LockHint
}

ReadOptions provides options for reading rows from a database.

type ReadWriteStmtBasedTransaction added in v1.8.0 

type ReadWriteStmtBasedTransaction struct {
	// ReadWriteTransaction contains methods for performing transactional reads.
	ReadWriteTransaction
	// contains filtered or unexported fields
}

ReadWriteStmtBasedTransaction provides a wrapper of ReadWriteTransaction in order to run a read-write transaction in a statement-based way.

This struct is returned by NewReadWriteStmtBasedTransaction and contains Commit() and Rollback() methods to end a transaction.

func NewReadWriteStmtBasedTransaction added in v1.8.0 

func NewReadWriteStmtBasedTransaction(ctx context.Context, c *Client) (*ReadWriteStmtBasedTransaction, error)

NewReadWriteStmtBasedTransaction starts a read-write transaction. Commit() or Rollback() must be called to end a transaction. If Commit() or Rollback() is not called, the session that is used by the transaction will not be returned to the pool and cause a session leak.

This method should only be used when manual error handling and retry management is needed. Cloud Spanner may abort a read/write transaction at any moment, and each statement that is executed on the transaction should be checked for an Aborted error, including queries and read operations.

For most use cases, client.ReadWriteTransaction should be used, as it will handle all Aborted and 'Session not found' errors automatically.

Example 
package main

import (
	"context"
	"errors"
	"time"

	"cloud.google.com/go/spanner"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	defer client.Close()

	f := func(tx *spanner.ReadWriteStmtBasedTransaction) error {
		var balance int64
		row, err := tx.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
		if err != nil {
			return err
		}
		if err := row.Column(0, &balance); err != nil {
			return err
		}

		if balance <= 10 {
			return errors.New("insufficient funds in account")
		}
		balance -= 10
		m := spanner.Update("Accounts", []string{"user", "balance"}, []interface{}{"alice", balance})
		return tx.BufferWrite([]*spanner.Mutation{m})
	}

	for {
		tx, err := spanner.NewReadWriteStmtBasedTransaction(ctx, client)
		if err != nil {
			// TODO: Handle error.
			break
		}
		err = f(tx)
		if err != nil && status.Code(err) != codes.Aborted {
			tx.Rollback(ctx)
			// TODO: Handle error.
			break
		} else if err == nil {
			_, err = tx.Commit(ctx)
			if err == nil {
				break
			} else if status.Code(err) != codes.Aborted {
				// TODO: Handle error.
				break
			}
		}
		// Set a default sleep time if the server delay is absent.
		delay := 10 * time.Millisecond
		if serverDelay, hasServerDelay := spanner.ExtractRetryDelay(err); hasServerDelay {
			delay = serverDelay
		}
		time.Sleep(delay)
	}
}

Output:

func NewReadWriteStmtBasedTransactionWithOptions added in v1.12.0 

func NewReadWriteStmtBasedTransactionWithOptions(ctx context.Context, c *Client, options TransactionOptions) (*ReadWriteStmtBasedTransaction, error)

NewReadWriteStmtBasedTransactionWithOptions starts a read-write transaction with configurable options. Commit() or Rollback() must be called to end a transaction. If Commit() or Rollback() is not called, the session that is used by the transaction will not be returned to the pool and cause a session leak.

NewReadWriteStmtBasedTransactionWithOptions is a configurable version of NewReadWriteStmtBasedTransaction.

func (*ReadWriteStmtBasedTransaction) AnalyzeQuery added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) AnalyzeQuery(ctx context.Context, statement Statement) (*sppb.QueryPlan, error)

AnalyzeQuery returns the query plan for statement.

func (*ReadWriteStmtBasedTransaction) Commit added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) Commit(ctx context.Context) (time.Time, error)

Commit tries to commit a readwrite transaction to Cloud Spanner. It also returns the commit timestamp for the transactions.

func (*ReadWriteStmtBasedTransaction) CommitWithReturnResp added in v1.14.0 

func (t *ReadWriteStmtBasedTransaction) CommitWithReturnResp(ctx context.Context) (CommitResponse, error)

CommitWithReturnResp tries to commit a readwrite transaction. It also returns the commit timestamp and stats for the transactions.

func (*ReadWriteStmtBasedTransaction) Query added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) Query(ctx context.Context, statement Statement) *RowIterator

Query executes a query against the database. It returns a RowIterator for retrieving the resulting rows.

Query returns only row data, without a query plan or execution statistics. Use QueryWithStats to get rows along with the plan and statistics. Use AnalyzeQuery to get just the plan.

func (*ReadWriteStmtBasedTransaction) QueryWithOptions added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) QueryWithOptions(ctx context.Context, statement Statement, opts QueryOptions) *RowIterator

QueryWithOptions executes a SQL statment against the database. It returns a RowIterator for retrieving the resulting rows. The sql query execution will be optimized based on the given query options.

func (*ReadWriteStmtBasedTransaction) QueryWithStats added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) QueryWithStats(ctx context.Context, statement Statement) *RowIterator

QueryWithStats executes a SQL statement against the database. It returns a RowIterator for retrieving the resulting rows. The RowIterator will also be populated with a query plan and execution statistics.

func (*ReadWriteStmtBasedTransaction) Read added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) Read(ctx context.Context, table string, keys KeySet, columns []string) *RowIterator

Read returns a RowIterator for reading multiple rows from the database.

func (*ReadWriteStmtBasedTransaction) ReadRow added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) ReadRow(ctx context.Context, table string, key Key, columns []string) (*Row, error)

ReadRow reads a single row from the database.

If no row is present with the given key, then ReadRow returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

func (*ReadWriteStmtBasedTransaction) ReadRowUsingIndex added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) ReadRowUsingIndex(ctx context.Context, table string, index string, key Key, columns []string) (*Row, error)

ReadRowUsingIndex reads a single row from the database using an index.

If no row is present with the given index, then ReadRowUsingIndex returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

If more than one row received with the given index, then ReadRowUsingIndex returns an error where spanner.ErrCode(err) is codes.FailedPrecondition.

func (*ReadWriteStmtBasedTransaction) ReadRowWithOptions added in v1.29.0 

func (t *ReadWriteStmtBasedTransaction) ReadRowWithOptions(ctx context.Context, table string, key Key, columns []string, opts *ReadOptions) (*Row, error)

ReadRowWithOptions reads a single row from the database. Pass a ReadOptions to modify the read operation.

If no row is present with the given key, then ReadRowWithOptions returns an error where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

func (*ReadWriteStmtBasedTransaction) ReadUsingIndex added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) ReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string) (ri *RowIterator)

ReadUsingIndex calls ReadWithOptions with ReadOptions{Index: index}.

func (*ReadWriteStmtBasedTransaction) ReadWithOptions added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) ReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opts *ReadOptions) (ri *RowIterator)

ReadWithOptions returns a RowIterator for reading multiple rows from the database. Pass a ReadOptions to modify the read operation.

func (*ReadWriteStmtBasedTransaction) Rollback added in v1.8.0 

func (t *ReadWriteStmtBasedTransaction) Rollback(ctx context.Context)

Rollback is called to cancel the ongoing transaction that has not been committed yet.

type ReadWriteTransaction 

type ReadWriteTransaction struct {
	// contains filtered or unexported fields
}

ReadWriteTransaction provides a locking read-write transaction.

This type of transaction is the only way to write data into Cloud Spanner; (*Client).Apply, (*Client).ApplyAtLeastOnce, (*Client).PartitionedUpdate use transactions internally. These transactions rely on pessimistic locking and, if necessary, two-phase commit. Locking read-write transactions may abort, requiring the application to retry. However, the interface exposed by (*Client).ReadWriteTransaction eliminates the need for applications to write retry loops explicitly.

Locking transactions may be used to atomically read-modify-write data anywhere in a database. This type of transaction is externally consistent.

Clients should attempt to minimize the amount of time a transaction is active. Faster transactions commit with higher probability and cause less contention. Cloud Spanner attempts to keep read locks active as long as the transaction continues to do reads. Long periods of inactivity at the client may cause Cloud Spanner to release a transaction's locks and abort it.

Reads performed within a transaction acquire locks on the data being read. Writes can only be done at commit time, after all reads have been completed. Conceptually, a read-write transaction consists of zero or more reads or SQL queries followed by a commit.

See (*Client).ReadWriteTransaction for an example.

Semantics

Cloud Spanner can commit the transaction if all read locks it acquired are still valid at commit time, and it is able to acquire write locks for all writes. Cloud Spanner can abort the transaction for any reason. If a commit attempt returns ABORTED, Cloud Spanner guarantees that the transaction has not modified any user data in Cloud Spanner.

Unless the transaction commits, Cloud Spanner makes no guarantees about how long the transaction's locks were held for. It is an error to use Cloud Spanner locks for any sort of mutual exclusion other than between Cloud Spanner transactions themselves.

Aborted transactions

Application code does not need to retry explicitly; RunInTransaction will automatically retry a transaction if an attempt results in an abort. The lock priority of a transaction increases after each prior aborted transaction, meaning that the next attempt has a slightly better chance of success than before.

Under some circumstances (e.g., many transactions attempting to modify the same row(s)), a transaction can abort many times in a short period before successfully committing. Thus, it is not a good idea to cap the number of retries a transaction can attempt; instead, it is better to limit the total amount of wall time spent retrying.

Idle transactions

A transaction is considered idle if it has no outstanding reads or SQL queries and has not started a read or SQL query within the last 10 seconds. Idle transactions can be aborted by Cloud Spanner so that they don't hold on to locks indefinitely. In that case, the commit will fail with error ABORTED.

If this behavior is undesirable, periodically executing a simple SQL query in the transaction (e.g., SELECT 1) prevents the transaction from becoming idle.

func (*ReadWriteTransaction) AnalyzeQuery 

func (t *ReadWriteTransaction) AnalyzeQuery(ctx context.Context, statement Statement) (*sppb.QueryPlan, error)

AnalyzeQuery returns the query plan for statement.

func (*ReadWriteTransaction) BatchUpdate 

func (t *ReadWriteTransaction) BatchUpdate(ctx context.Context, stmts []Statement) (_ []int64, err error)

BatchUpdate groups one or more DML statements and sends them to Spanner in a single RPC. This is an efficient way to execute multiple DML statements.

A slice of counts is returned, where each count represents the number of affected rows for the given query at the same index. If an error occurs, counts will be returned up to the query that encountered the error.

func (*ReadWriteTransaction) BatchUpdateWithOptions added in v1.17.0 

func (t *ReadWriteTransaction) BatchUpdateWithOptions(ctx context.Context, stmts []Statement, opts QueryOptions) (_ []int64, err error)

BatchUpdateWithOptions groups one or more DML statements and sends them to Spanner in a single RPC. This is an efficient way to execute multiple DML statements.

A slice of counts is returned, where each count represents the number of affected rows for the given query at the same index. If an error occurs, counts will be returned up to the query that encountered the error.

The request tag and priority given in the QueryOptions are included with the RPC. Any other options that are set in the QueryOptions struct are ignored.

func (*ReadWriteTransaction) BufferWrite 

func (t *ReadWriteTransaction) BufferWrite(ms []*Mutation) error

BufferWrite adds a list of mutations to the set of updates that will be applied when the transaction is committed. It does not actually apply the write until the transaction is committed, so the operation does not block. The effects of the write won't be visible to any reads (including reads done in the same transaction) until the transaction commits.

See the example for Client.ReadWriteTransaction.

func (*ReadWriteTransaction) Query 

func (t *ReadWriteTransaction) Query(ctx context.Context, statement Statement) *RowIterator

Query executes a query against the database. It returns a RowIterator for retrieving the resulting rows.

Query returns only row data, without a query plan or execution statistics. Use QueryWithStats to get rows along with the plan and statistics. Use AnalyzeQuery to get just the plan.

func (*ReadWriteTransaction) QueryWithOptions added in v1.3.0 

func (t *ReadWriteTransaction) QueryWithOptions(ctx context.Context, statement Statement, opts QueryOptions) *RowIterator

QueryWithOptions executes a SQL statment against the database. It returns a RowIterator for retrieving the resulting rows. The sql query execution will be optimized based on the given query options.

func (*ReadWriteTransaction) QueryWithStats 

func (t *ReadWriteTransaction) QueryWithStats(ctx context.Context, statement Statement) *RowIterator

QueryWithStats executes a SQL statement against the database. It returns a RowIterator for retrieving the resulting rows. The RowIterator will also be populated with a query plan and execution statistics.

func (*ReadWriteTransaction) Read 

func (t *ReadWriteTransaction) Read(ctx context.Context, table string, keys KeySet, columns []string) *RowIterator

Read returns a RowIterator for reading multiple rows from the database.

func (*ReadWriteTransaction) ReadRow 

func (t *ReadWriteTransaction) ReadRow(ctx context.Context, table string, key Key, columns []string) (*Row, error)

ReadRow reads a single row from the database.

If no row is present with the given key, then ReadRow returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

func (*ReadWriteTransaction) ReadRowUsingIndex added in v1.2.0 

func (t *ReadWriteTransaction) ReadRowUsingIndex(ctx context.Context, table string, index string, key Key, columns []string) (*Row, error)

ReadRowUsingIndex reads a single row from the database using an index.

If no row is present with the given index, then ReadRowUsingIndex returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

If more than one row received with the given index, then ReadRowUsingIndex returns an error where spanner.ErrCode(err) is codes.FailedPrecondition.

func (*ReadWriteTransaction) ReadRowWithOptions added in v1.29.0 

func (t *ReadWriteTransaction) ReadRowWithOptions(ctx context.Context, table string, key Key, columns []string, opts *ReadOptions) (*Row, error)

ReadRowWithOptions reads a single row from the database. Pass a ReadOptions to modify the read operation.

If no row is present with the given key, then ReadRowWithOptions returns an error where spanner.ErrCode(err) is codes.NotFound.

To check if the error is spanner.ErrRowNotFound: 

if errors.Is(err, spanner.ErrRowNotFound) {
		...
}

func (*ReadWriteTransaction) ReadUsingIndex 

func (t *ReadWriteTransaction) ReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string) (ri *RowIterator)

ReadUsingIndex calls ReadWithOptions with ReadOptions{Index: index}.

func (*ReadWriteTransaction) ReadWithOptions 

func (t *ReadWriteTransaction) ReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opts *ReadOptions) (ri *RowIterator)

ReadWithOptions returns a RowIterator for reading multiple rows from the database. Pass a ReadOptions to modify the read operation.

func (*ReadWriteTransaction) Update 

func (t *ReadWriteTransaction) Update(ctx context.Context, stmt Statement) (rowCount int64, err error)

Update executes a DML statement against the database. It returns the number of affected rows. Update returns an error if the statement is a query. However, the query is executed, and any data read will be validated upon commit.

func (*ReadWriteTransaction) UpdateWithOptions added in v1.3.0 

func (t *ReadWriteTransaction) UpdateWithOptions(ctx context.Context, stmt Statement, opts QueryOptions) (rowCount int64, err error)

UpdateWithOptions executes a DML statement against the database. It returns the number of affected rows. The given QueryOptions will be used for the execution of this statement.

type Row 

type Row struct {
	// contains filtered or unexported fields
}

A Row is a view of a row of data returned by a Cloud Spanner read. It consists of a number of columns; the number depends on the columns used to construct the read.

The column values can be accessed by index. For instance, if the read specified []string{"photo_id", "caption"}, then each row will contain two columns: "photo_id" with index 0, and "caption" with index 1.

Column values are decoded by using one of the Column, ColumnByName, or Columns methods. The valid values passed to these methods depend on the column type. For example: 

var photoID int64
err := row.Column(0, &photoID) // Decode column 0 as an integer.

var caption string
err := row.Column(1, &caption) // Decode column 1 as a string.

// Decode all the columns.
err := row.Columns(&photoID, &caption)

Supported types and their corresponding Cloud Spanner column type(s) are: 

*string(not NULL), *NullString - STRING
*[]string, *[]NullString - STRING ARRAY
*[]byte - BYTES
*[][]byte - BYTES ARRAY
*int64(not NULL), *NullInt64 - INT64
*[]int64, *[]NullInt64 - INT64 ARRAY
*bool(not NULL), *NullBool - BOOL
*[]bool, *[]NullBool - BOOL ARRAY
*float32(not NULL), *NullFloat32 - FLOAT32
*[]float32, *[]NullFloat32 - FLOAT32 ARRAY
*float64(not NULL), *NullFloat64 - FLOAT64
*[]float64, *[]NullFloat64 - FLOAT64 ARRAY
*big.Rat(not NULL), *NullNumeric - NUMERIC
*[]big.Rat, *[]NullNumeric - NUMERIC ARRAY
*time.Time(not NULL), *NullTime - TIMESTAMP
*[]time.Time, *[]NullTime - TIMESTAMP ARRAY
*Date(not NULL), *NullDate - DATE
*[]civil.Date, *[]NullDate - DATE ARRAY
*[]*some_go_struct, *[]NullRow - STRUCT ARRAY
*NullJSON - JSON
*[]NullJSON - JSON ARRAY
*GenericColumnValue - any Cloud Spanner type

For TIMESTAMP columns, the returned time.Time object will be in UTC.

To fetch an array of BYTES, pass a *[][]byte. To fetch an array of (sub)rows, pass a *[]spanner.NullRow or a *[]*some_go_struct where some_go_struct holds all information of the subrow, see spanner.Row.ToStruct for the mapping between a Cloud Spanner row and a Go struct. To fetch an array of other types, pass a *[]spanner.NullXXX type of the appropriate type. Use GenericColumnValue when you don't know in advance what column type to expect.

Row decodes the row contents lazily; as a result, each call to a getter has a chance of returning an error.

A column value may be NULL if the corresponding value is not present in Cloud Spanner. The spanner.NullXXX types (spanner.NullInt64 et al.) allow fetching values that may be null. A NULL BYTES can be fetched into a *[]byte as nil. It is an error to fetch a NULL value into any other type.

func NewRow 

func NewRow(columnNames []string, columnValues []interface{}) (*Row, error)

NewRow returns a Row containing the supplied data. This can be useful for mocking Cloud Spanner Read and Query responses for unit testing.

func (*Row) Column 

func (r *Row) Column(i int, ptr interface{}) error

Column fetches the value from the ith column, decoding it into ptr. See the Row documentation for the list of acceptable argument types. see Client.ReadWriteTransaction for an example.

func (*Row) ColumnByName 

func (r *Row) ColumnByName(name string, ptr interface{}) error

ColumnByName fetches the value from the named column, decoding it into ptr. See the Row documentation for the list of acceptable argument types.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
	if err != nil {
		// TODO: Handle error.
	}
	var balance int64
	if err := row.ColumnByName("balance", &balance); err != nil {
		// TODO: Handle error.
	}
	fmt.Println(balance)
}

Output:

func (*Row) ColumnIndex 

func (r *Row) ColumnIndex(name string) (int, error)

ColumnIndex returns the index of the column with the given name. The comparison is case-sensitive.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
	if err != nil {
		// TODO: Handle error.
	}
	index, err := row.ColumnIndex("balance")
	if err != nil {
		// TODO: Handle error.
	}
	fmt.Println(index)
}

Output:

func (*Row) ColumnName 

func (r *Row) ColumnName(i int) string

ColumnName returns the name of column i, or empty string for invalid column.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
	if err != nil {
		// TODO: Handle error.
	}
	fmt.Println(row.ColumnName(1)) // "balance"
}

Output:

func (*Row) ColumnNames 

func (r *Row) ColumnNames() []string

ColumnNames returns all column names of the row.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
	if err != nil {
		// TODO: Handle error.
	}
	fmt.Println(row.ColumnNames())
}

Output:

func (*Row) ColumnType added in v1.52.0 

func (r *Row) ColumnType(i int) *sppb.Type

ColumnType returns the Cloud Spanner Type of column i, or nil for invalid column.

func (*Row) ColumnValue added in v1.52.0 

func (r *Row) ColumnValue(i int) *proto3.Value

ColumnValue returns the Cloud Spanner Value of column i, or nil for invalid column.

func (*Row) Columns 

func (r *Row) Columns(ptrs ...interface{}) error

Columns fetches all the columns in the row at once.

The value of the kth column will be decoded into the kth argument to Columns. See Row for the list of acceptable argument types. The number of arguments must be equal to the number of columns. Pass nil to specify that a column should be ignored.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
	if err != nil {
		// TODO: Handle error.
	}
	var name string
	var balance int64
	if err := row.Columns(&name, &balance); err != nil {
		// TODO: Handle error.
	}
	fmt.Println(name, balance)
}

Output:

func (*Row) Size 

func (r *Row) Size() int

Size is the number of columns in the row.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
	if err != nil {
		// TODO: Handle error.
	}
	fmt.Println(row.Size()) // 2
}

Output:

func (*Row) String added in v1.24.0 

func (r *Row) String() string

String implements fmt.stringer.

func (*Row) ToStruct 

func (r *Row) ToStruct(p interface{}) error

ToStruct fetches the columns in a row into the fields of a struct. The rules for mapping a row's columns into a struct's exported fields are:

  1. If a field has a `spanner: "column_name"` tag, then decode column 'column_name' into the field. A special case is the `spanner: "-"` tag, which instructs ToStruct to ignore the field during decoding.

  2. Otherwise, if the name of a field matches the name of a column (ignoring case), decode the column into the field.

  3. The number of columns in the row must match the number of exported fields in the struct. There must be exactly one match for each column in the row. The method will return an error if a column in the row cannot be assigned to a field in the struct.

The fields of the destination struct can be of any type that is acceptable to spanner.Row.Column.

Slice and pointer fields will be set to nil if the source column is NULL, and a non-nil value if the column is not NULL. To decode NULL values of other types, use one of the spanner.NullXXX types as the type of the destination field.

If ToStruct returns an error, the contents of p are undefined. Some fields may have been successfully populated, while others were not; you should not use any of the fields.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
	if err != nil {
		// TODO: Handle error.
	}

	type Account struct {
		Name    string
		Balance int64
	}

	var acct Account
	if err := row.ToStruct(&acct); err != nil {
		// TODO: Handle error.
	}
	fmt.Println(acct)
}

Output:

func (*Row) ToStructLenient added in v1.28.0 

func (r *Row) ToStructLenient(p interface{}) error

ToStructLenient fetches the columns in a row into the fields of a struct. The rules for mapping a row's columns into a struct's exported fields are:

  1. If a field has a `spanner: "column_name"` tag, then decode column 'column_name' into the field. A special case is the `spanner: "-"` tag, which instructs ToStruct to ignore the field during decoding.

  2. Otherwise, if the name of a field matches the name of a column (ignoring case), decode the column into the field.

  3. The number of columns in the row and exported fields in the struct do not need to match. Any field in the struct that cannot not be assigned a value from the row is assigned its default value. Any column in the row that does not have a corresponding field in the struct is ignored.

The fields of the destination struct can be of any type that is acceptable to spanner.Row.Column.

Slice and pointer fields will be set to nil if the source column is NULL, and a non-nil value if the column is not NULL. To decode NULL values of other types, use one of the spanner.NullXXX types as the type of the destination field.

If ToStructLenient returns an error, the contents of p are undefined. Some fields may have been successfully populated, while others were not; you should not use any of the fields.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"accountID", "name", "balance"})
	if err != nil {
		// TODO: Handle error.
	}

	type Account struct {
		Name     string
		Balance  int64
		NickName string
	}

	var acct Account
	if err := row.ToStructLenient(&acct); err != nil {
		// TODO: Handle error.
	}
	fmt.Println(acct)
}

Output:

type RowIterator 

type RowIterator struct {
	// The plan for the query. Available after RowIterator.Next returns
	// iterator.Done if QueryWithStats was called.
	QueryPlan *sppb.QueryPlan

	// Execution statistics for the query. Available after RowIterator.Next
	// returns iterator.Done if QueryWithStats was called.
	QueryStats map[string]interface{}

	// For a DML statement, the number of rows affected. For PDML, this is a
	// lower bound. Available for DML statements after RowIterator.Next returns
	// iterator.Done.
	RowCount int64

	// The metadata of the results of the query. The metadata are available
	// after the first call to RowIterator.Next(), unless the first call to
	// RowIterator.Next() returned an error that is not equal to iterator.Done.
	Metadata *sppb.ResultSetMetadata
	// contains filtered or unexported fields
}

RowIterator is an iterator over Rows.

func (*RowIterator) Do 

func (r *RowIterator) Do(f func(r *Row) error) error

Do calls the provided function once in sequence for each row in the iteration. If the function returns a non-nil error, Do immediately returns that error.

If there are no rows in the iterator, Do will return nil without calling the provided function.

Do always calls Stop on the iterator.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	iter := client.Single().Query(ctx, spanner.NewStatement("SELECT FirstName FROM Singers"))
	err = iter.Do(func(r *spanner.Row) error {
		var firstName string
		if err := r.Column(0, &firstName); err != nil {
			return err
		}
		fmt.Println(firstName)
		return nil
	})
	if err != nil {
		// TODO: Handle error.
	}
}

Output:

func (*RowIterator) Next 

func (r *RowIterator) Next() (*Row, error)

Next returns the next result. Its second return value is iterator.Done if there are no more results. Once Next returns Done, all subsequent calls will return Done.

Example 
package main

import (
	"context"
	"fmt"

	"cloud.google.com/go/spanner"
	"google.golang.org/api/iterator"
)

const myDB = "projects/my-project/instances/my-instance/database/my-db"

func main() {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, myDB)
	if err != nil {
		// TODO: Handle error.
	}
	iter := client.Single().Query(ctx, spanner.NewStatement("SELECT FirstName FROM Singers"))
	defer iter.Stop()
	for {
		row, err := iter.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			// TODO: Handle error.
		}
		var firstName string
		if err := row.Column(0, &firstName); err != nil {
			// TODO: Handle error.
		}
		fmt.Println(firstName)
	}
}

Output:

func (*RowIterator) Stop 

func (r *RowIterator) Stop()

Stop terminates the iteration. It should be called after you finish using the iterator.

type SessionPoolConfig 

type SessionPoolConfig struct {
	// MaxOpened is the maximum number of opened sessions allowed by the session
	// pool. If the client tries to open a session and there are already
	// MaxOpened sessions, it will block until one becomes available or the
	// context passed to the client method is canceled or times out.
	//
	// Defaults to NumChannels * 100.
	MaxOpened uint64

	// MinOpened is the minimum number of opened sessions that the session pool
	// tries to maintain. Session pool won't continue to expire sessions if
	// number of opened connections drops below MinOpened. However, if a session
	// is found to be broken, it will still be evicted from the session pool,
	// therefore it is posssible that the number of opened sessions drops below
	// MinOpened.
	//
	// Defaults to 100.
	MinOpened uint64

	// MaxIdle is the maximum number of idle sessions that are allowed in the
	// session pool.
	//
	// Defaults to 0.
	MaxIdle uint64

	// MaxBurst is the maximum number of concurrent session creation requests.
	//
	// Deprecated: MaxBurst exists for historical compatibility and should not
	// be used. MaxBurst was used to limit the number of sessions that the
	// session pool could create within a time frame. This was an early safety
	// valve to prevent a client from overwhelming the backend if a large number
	// of sessions was suddenly needed. The session pool would then pause the
	// creation of sessions for a while. Such a pause is no longer needed and
	// the implementation has been removed from the pool.
	//
	// Defaults to 10.
	MaxBurst uint64

	// WriteSessions is the fraction of sessions we try to keep prepared for
	// write.
	//
	// Deprecated: The session pool no longer prepares a fraction of the sessions with a read/write transaction.
	// This setting therefore does not have any meaning anymore, and may be removed in the future.
	//
	// Defaults to 0.2.
	WriteSessions float64

	// HealthCheckWorkers is number of workers used by health checker for this
	// pool.
	//
	// Defaults to 10.
	HealthCheckWorkers int

	// HealthCheckInterval is how often the health checker pings a session.
	//
	// Defaults to 50m.
	HealthCheckInterval time.Duration

	// TrackSessionHandles determines whether the session pool will keep track
	// of the stacktrace of the goroutines that take sessions from the pool.
	// This setting can be used to track down session leak problems.
	//
	// Defaults to false.
	TrackSessionHandles bool

	InactiveTransactionRemovalOptions
	// contains filtered or unexported fields
}

SessionPoolConfig stores configurations of a session pool.

type Statement 

type Statement struct {
	SQL    string
	Params map[string]interface{}
}

A Statement is a SQL query with named parameters.

A parameter placeholder consists of '@' followed by the parameter name. The parameter name is an identifier which must conform to the naming requirements in https://cloud.google.com/spanner/docs/lexical#identifiers. Parameters may appear anywhere that a literal value is expected. The same parameter name may be used more than once. It is an error to execute a statement with unbound parameters. On the other hand, it is allowable to bind parameter names that are not used.

See the documentation of the Row type for how Go types are mapped to Cloud Spanner types.

Example (ArrayOfStructParam) 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	stmt := spanner.Statement{
		SQL: "SELECT * FROM SINGERS WHERE (FirstName, LastName) IN UNNEST(@singerinfo)",
		Params: map[string]interface{}{
			"singerinfo": []struct {
				FirstName string
				LastName  string
			}{
				{"Ringo", "Starr"},
				{"John", "Lennon"},
			},
		},
	}
	_ = stmt // TODO: Use stmt in Query.
}

Output:
Example (RegexpContains) 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	// Search for accounts with valid emails using regexp as per:
	//   https://cloud.google.com/spanner/docs/functions-and-operators#regexp_contains
	stmt := spanner.Statement{
		SQL: `SELECT * FROM users WHERE REGEXP_CONTAINS(email, @valid_email)`,
		Params: map[string]interface{}{
			"valid_email": `\Q@\E`,
		},
	}
	_ = stmt // TODO: Use stmt in a query.
}

Output:
Example (StructParam) 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	stmt := spanner.Statement{
		SQL: "SELECT * FROM SINGERS WHERE (FirstName, LastName) = @singerinfo",
		Params: map[string]interface{}{
			"singerinfo": struct {
				FirstName string
				LastName  string
			}{"Bob", "Dylan"},
		},
	}
	_ = stmt // TODO: Use stmt in Query.
}

Output:

func NewStatement 

func NewStatement(sql string) Statement

NewStatement returns a Statement with the given SQL and an empty Params map.

Example 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	stmt := spanner.NewStatement("SELECT FirstName, LastName FROM SINGERS WHERE LastName >= @start")
	stmt.Params["start"] = "Dylan"
	// TODO: Use stmt in Query.
}

Output:
Example (StructLiteral) 
package main

import (
	"cloud.google.com/go/spanner"
)

func main() {
	stmt := spanner.Statement{
		SQL: `SELECT FirstName, LastName FROM SINGERS WHERE LastName = ("Lea", "Martin")`,
	}
	_ = stmt // TODO: Use stmt in Query.
}

Output:

type TimestampBound 

type TimestampBound struct {
	// contains filtered or unexported fields
}

TimestampBound defines how Cloud Spanner will choose a timestamp for a single read/query or read-only transaction.

There are three types of timestamp bound: strong, bounded staleness and exact staleness. Strong is the default.

If the Cloud Spanner database to be read is geographically distributed, stale read-only transactions can execute more quickly than strong or read-write transactions, because they are able to execute far from the leader replica.

Each type of timestamp bound is discussed in detail below. A TimestampBound can be specified when creating transactions, see the documentation of spanner.Client for an example.

Strong reads

Strong reads are guaranteed to see the effects of all transactions that have committed before the start of the read. Furthermore, all rows yielded by a single read are consistent with each other: if any part of the read observes a transaction, all parts of the read see the transaction.

Strong reads are not repeatable: two consecutive strong read-only transactions might return inconsistent results if there are concurrent writes. If consistency across reads is required, the reads should be executed within a transaction or at an exact read timestamp.

Use StrongRead to create a bound of this type.

Exact staleness

An exact staleness timestamp bound executes reads at a user-specified timestamp. Reads at a timestamp are guaranteed to see a consistent prefix of the global transaction history: they observe modifications done by all transactions with a commit timestamp less than or equal to the read timestamp, and observe none of the modifications done by transactions with a larger commit timestamp. They will block until all conflicting transactions that may be assigned commit timestamps less than or equal to the read timestamp have finished.

The timestamp can either be expressed as an absolute Cloud Spanner commit timestamp or a staleness relative to the current time.

These modes do not require a "negotiation phase" to pick a timestamp. As a result, they execute slightly faster than the equivalent boundedly stale concurrency modes. On the other hand, boundedly stale reads usually return fresher results.

Use ReadTimestamp and ExactStaleness to create a bound of this type.

Bounded staleness

Bounded staleness modes allow Cloud Spanner to pick the read timestamp, subject to a user-provided staleness bound. Cloud Spanner chooses the newest timestamp within the staleness bound that allows execution of the reads at the closest available replica without blocking.

All rows yielded are consistent with each other: if any part of the read observes a transaction, all parts of the read see the transaction. Boundedly stale reads are not repeatable: two stale reads, even if they use the same staleness bound, can execute at different timestamps and thus return inconsistent results.

Boundedly stale reads execute in two phases. The first phase negotiates a timestamp among all replicas needed to serve the read. In the second phase, reads are executed at the negotiated timestamp.

As a result of this two-phase execution, bounded staleness reads are usually a little slower than comparable exact staleness reads. However, they are typically able to return fresher results, and are more likely to execute at the closest replica.

Because the timestamp negotiation requires up-front knowledge of which rows will be read, it can only be used with single-use reads and single-use read-only transactions.

Use MinReadTimestamp and MaxStaleness to create a bound of this type.

Old read timestamps and garbage collection

Cloud Spanner continuously garbage collects deleted and overwritten data in the background to reclaim storage space. This process is known as "version GC". By default, version GC reclaims versions after they are one hour old. Because of this, Cloud Spanner cannot perform reads at read timestamps more than one hour in the past. This restriction also applies to in-progress reads and/or SQL queries whose timestamps become too old while executing. Reads and SQL queries with too-old read timestamps fail with the error ErrorCode.FAILED_PRECONDITION.

func ExactStaleness 

func ExactStaleness(d time.Duration) TimestampBound

ExactStaleness returns a TimestampBound that will perform reads and queries at an exact staleness.

func MaxStaleness 

func MaxStaleness(d time.Duration) TimestampBound

MaxStaleness returns a TimestampBound that will perform reads and queries at a time chosen to be at most "d" stale.

func MinReadTimestamp 

func MinReadTimestamp(t time.Time) TimestampBound

MinReadTimestamp returns a TimestampBound that bound that will perform reads and queries at a time chosen to be at least "t".

func ReadTimestamp 

func ReadTimestamp(t time.Time) TimestampBound

ReadTimestamp returns a TimestampBound that will peform reads and queries at the given time.

func StrongRead 

func StrongRead() TimestampBound

StrongRead returns a TimestampBound that will perform reads and queries at a timestamp where all previously committed transactions are visible.

func (TimestampBound) String 

func (tb TimestampBound) String() string

type TransactionOptions added in v1.12.0 

type TransactionOptions struct {
	CommitOptions CommitOptions

	// The transaction tag to use for a read/write transaction.
	// This tag is automatically included with each statement and the commit
	// request of a read/write transaction.
	TransactionTag string

	// CommitPriority is the priority to use for the Commit RPC for the
	// transaction.
	CommitPriority sppb.RequestOptions_Priority

	// the transaction lock mode is used to specify a concurrency mode for the
	// read/query operations. It works for a read/write transaction only.
	ReadLockMode sppb.TransactionOptions_ReadWrite_ReadLockMode

	// Controls whether to exclude recording modifications in current transaction
	// from the allowed tracking change streams(with DDL option allow_txn_exclusion=true).
	ExcludeTxnFromChangeStreams bool
}

TransactionOptions provides options for a transaction.

type TransactionOutcomeUnknownError added in v1.3.0 

type TransactionOutcomeUnknownError struct {
	// contains filtered or unexported fields
}

TransactionOutcomeUnknownError is wrapped in a Spanner error when the error occurred during a transaction, and the outcome of the transaction is unknown as a result of the error. This could be the case if a timeout or canceled error occurs after a Commit request has been sent, but before the client has received a response from the server.

func (*TransactionOutcomeUnknownError) Error added in v1.3.0 

func (*TransactionOutcomeUnknownError) Error() string

Error implements error.Error.

func (*TransactionOutcomeUnknownError) Unwrap added in v1.3.0 

func (e *TransactionOutcomeUnknownError) Unwrap() error

Unwrap returns the wrapped error (if any).

Source Files

View all Source files

Directories

Path Synopsis
admin
database/apiv1
database/apiv1/databasepb
instance/apiv1
Package instance is an auto-generated package for the Cloud Spanner Instance Admin API.
 Package instance is an auto-generated package for the Cloud Spanner Instance Admin API.
instance/apiv1/instancepb
Package spanner is an auto-generated package for the Cloud Spanner API.
 Package spanner is an auto-generated package for the Cloud Spanner API.
spannerpb
executor
apiv1
Package executor is an auto-generated package for the Cloud Spanner Executor test API.
 Package executor is an auto-generated package for the Cloud Spanner Executor test API.
apiv1/executorpb
benchwrapper
Package main wraps the client library in a gRPC interface that a benchmarker can communicate through.
 Package main wraps the client library in a gRPC interface that a benchmarker can communicate through.
benchwrapper/proto
testutil
Package spannertest contains test helpers for working with Cloud Spanner.
 Package spannertest contains test helpers for working with Cloud Spanner.
Package spansql contains types and a parser for the Cloud Spanner SQL dialect.
 Package spansql contains types and a parser for the Cloud Spanner SQL dialect.
test
cloudexecutor
cloudexecutor/executor
cloudexecutor/executor/actions
cloudexecutor/executor/internal/inputstream
cloudexecutor/executor/internal/outputstream
cloudexecutor/executor/internal/utility

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