pgconn

package
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 Go to latest Published: Sep 23, 2024 License: MIT Imports: 35 Imported by: 0

README

pgconn

Package pgconn is a low-level PostgreSQL database driver. It operates at nearly the same level as the C library libpq. It is primarily intended to serve as the foundation for higher level libraries such as https://github.com/jackc/pgx. Applications should handle normal queries with a higher level library and only use pgconn directly when required for low-level access to PostgreSQL functionality.

Example Usage

pgConn, err := pgconn.Connect(context.Background(), os.Getenv("DATABASE_URL"))
if err != nil {
	log.Fatalln("pgconn failed to connect:", err)
}
defer pgConn.Close(context.Background())

result := pgConn.ExecParams(context.Background(), "SELECT email FROM users WHERE id=$1", [][]byte{[]byte("123")}, nil, nil, nil)
for result.NextRow() {
	fmt.Println("User 123 has email:", string(result.Values()[0]))
}
_, err = result.Close()
if err != nil {
	log.Fatalln("failed reading result:", err)
}

Testing

See CONTRIBUTING.md for setup instructions.

Documentation

Overview

Package pgconn is a low-level PostgreSQL database driver.

pgconn provides lower level access to a PostgreSQL connection than a database/sql or pgx connection. It operates at nearly the same level is the C library libpq.

Establishing a Connection

Use Connect to establish a connection. It accepts a connection string in URL or keyword/value format and will read the environment for libpq style environment variables.

Executing a Query

ExecParams and ExecPrepared execute a single query. They return readers that iterate over each row. The Read method reads all rows into memory.

Executing Multiple Queries in a Single Round Trip

Exec and ExecBatch can execute multiple queries in a single round trip. They return readers that iterate over each query result. The ReadAll method reads all query results into memory.

Pipeline Mode

Pipeline mode allows sending queries without having read the results of previously sent queries. It allows control of exactly how many and when network round trips occur.

Context Support

All potentially blocking operations take a context.Context. The default behavior when a context is canceled is for the method to immediately return. In most circumstances, this will also close the underlying connection. This behavior can be customized by using BuildContextWatcherHandler on the Config to create a ctxwatch.Handler with different behavior. This can be especially useful when queries that are frequently canceled and the overhead of creating new connections is a problem. DeadlineContextWatcherHandler and CancelRequestContextWatcherHandler can be used to introduce a delay before interrupting the query in such a way as to close the connection.

The CancelRequest method may be used to request the PostgreSQL server cancel an in-progress query without forcing the client to abort.

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"time"

	"github.com/jackc/pgx/v5/pgconn"
)

func main() {
	ctx, cancel := context.WithTimeout(context.Background(), 120*time.Second)
	defer cancel()

	pgConn, err := pgconn.Connect(ctx, os.Getenv("PGX_TEST_DATABASE"))
	if err != nil {
		log.Fatalln(err)
	}
	defer pgConn.Close(ctx)

	result := pgConn.ExecParams(ctx, "select generate_series(1,3)", nil, nil, nil, nil).Read()
	if result.Err != nil {
		log.Fatalln(result.Err)
	}

	for _, row := range result.Rows {
		fmt.Println(string(row[0]))
	}

	fmt.Println(result.CommandTag)
}

Output:

1
2
3
SELECT 3

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func NetworkAddress 

func NetworkAddress(host string, port uint16) (network, address string)

NetworkAddress converts a PostgreSQL host and port into network and address suitable for use with net.Dial.

func RegisterGSSProvider 

func RegisterGSSProvider(newGSSArg NewGSSFunc)

RegisterGSSProvider registers a GSS authentication provider. For example, if you need to use Kerberos to authenticate with your server, add this to your main package: 

import "github.com/otan/gopgkrb5"

func init() {
	pgconn.RegisterGSSProvider(func() (pgconn.GSS, error) { return gopgkrb5.NewGSS() })
}

func SafeToRetry 

func SafeToRetry(err error) bool

SafeToRetry checks if the err is guaranteed to have occurred before sending any data to the server.

func Timeout 

func Timeout(err error) bool

Timeout checks if err was caused by a timeout. To be specific, it is true if err was caused within pgconn by a context.DeadlineExceeded or an implementer of net.Error where Timeout() is true.

func ValidateConnectTargetSessionAttrsPreferStandby 

func ValidateConnectTargetSessionAttrsPreferStandby(ctx context.Context, pgConn *PgConn) error

ValidateConnectTargetSessionAttrsPreferStandby is a ValidateConnectFunc that implements libpq compatible target_session_attrs=prefer-standby.

func ValidateConnectTargetSessionAttrsPrimary 

func ValidateConnectTargetSessionAttrsPrimary(ctx context.Context, pgConn *PgConn) error

ValidateConnectTargetSessionAttrsPrimary is a ValidateConnectFunc that implements libpq compatible target_session_attrs=primary.

func ValidateConnectTargetSessionAttrsReadOnly 

func ValidateConnectTargetSessionAttrsReadOnly(ctx context.Context, pgConn *PgConn) error

ValidateConnectTargetSessionAttrsReadOnly is a ValidateConnectFunc that implements libpq compatible target_session_attrs=read-only.

func ValidateConnectTargetSessionAttrsReadWrite 

func ValidateConnectTargetSessionAttrsReadWrite(ctx context.Context, pgConn *PgConn) error

ValidateConnectTargetSessionAttrsReadWrite is a ValidateConnectFunc that implements libpq compatible target_session_attrs=read-write.

func ValidateConnectTargetSessionAttrsStandby 

func ValidateConnectTargetSessionAttrsStandby(ctx context.Context, pgConn *PgConn) error

ValidateConnectTargetSessionAttrsStandby is a ValidateConnectFunc that implements libpq compatible target_session_attrs=standby.

Types

type AfterConnectFunc 

type AfterConnectFunc func(ctx context.Context, pgconn *PgConn) error

type Batch 

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

Batch is a collection of queries that can be sent to the PostgreSQL server in a single round-trip.

func (*Batch) ExecParams 

func (batch *Batch) ExecParams(sql string, paramValues [][]byte, paramOIDs []uint32, paramFormats []int16, resultFormats []int16)

ExecParams appends an ExecParams command to the batch. See PgConn.ExecParams for parameter descriptions.

func (*Batch) ExecPrepared 

func (batch *Batch) ExecPrepared(stmtName string, paramValues [][]byte, paramFormats []int16, resultFormats []int16)

ExecPrepared appends an ExecPrepared e command to the batch. See PgConn.ExecPrepared for parameter descriptions.

type BuildFrontendFunc 

type BuildFrontendFunc func(r io.Reader, w io.Writer) *pgproto3.Frontend

BuildFrontendFunc is a function that can be used to create Frontend implementation for connection.

type CancelRequestContextWatcherHandler 

type CancelRequestContextWatcherHandler struct {
	Conn *PgConn

	// CancelRequestDelay is the delay before sending the cancel request to the server.
	CancelRequestDelay time.Duration

	// DeadlineDelay is the delay to set on the deadline set on net.Conn when the context is canceled.
	DeadlineDelay time.Duration
	// contains filtered or unexported fields
}

CancelRequestContextWatcherHandler handles canceled contexts by sending a cancel request to the server. It also sets a deadline on a net.Conn as a fallback.

func (*CancelRequestContextWatcherHandler) HandleCancel 

func (h *CancelRequestContextWatcherHandler) HandleCancel(context.Context)

func (*CancelRequestContextWatcherHandler) HandleUnwatchAfterCancel 

func (h *CancelRequestContextWatcherHandler) HandleUnwatchAfterCancel()

type CloseComplete 

type CloseComplete struct{}

CloseComplete is returned by GetResults when a CloseComplete message is received.

type CommandTag 

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

CommandTag is the status text returned by PostgreSQL for a query.

func NewCommandTag 

func NewCommandTag(s string) CommandTag

NewCommandTag makes a CommandTag from s.

func (CommandTag) Delete 

func (ct CommandTag) Delete() bool

Delete is true if the command tag starts with "DELETE".

func (CommandTag) Insert 

func (ct CommandTag) Insert() bool

Insert is true if the command tag starts with "INSERT".

func (CommandTag) RowsAffected 

func (ct CommandTag) RowsAffected() int64

RowsAffected returns the number of rows affected. If the CommandTag was not for a row affecting command (e.g. "CREATE TABLE") then it returns 0.

func (CommandTag) Select 

func (ct CommandTag) Select() bool

Select is true if the command tag starts with "SELECT".

func (CommandTag) String 

func (ct CommandTag) String() string

func (CommandTag) Update 

func (ct CommandTag) Update() bool

Update is true if the command tag starts with "UPDATE".

type Config 

type Config struct {
	Host           string // host (e.g. localhost) or absolute path to unix domain socket directory (e.g. /private/tmp)
	Port           uint16
	Database       string
	User           string
	Password       string
	TLSConfig      *tls.Config // nil disables TLS
	ConnectTimeout time.Duration
	DialFunc       DialFunc   // e.g. net.Dialer.DialContext
	LookupFunc     LookupFunc // e.g. net.Resolver.LookupHost
	BuildFrontend  BuildFrontendFunc

	// BuildContextWatcherHandler is called to create a ContextWatcherHandler for a connection. The handler is called
	// when a context passed to a PgConn method is canceled.
	BuildContextWatcherHandler func(*PgConn) ctxwatch.Handler

	RuntimeParams map[string]string // Run-time parameters to set on connection as session default values (e.g. search_path or application_name)

	KerberosSrvName string
	KerberosSpn     string
	Fallbacks       []*FallbackConfig

	// ValidateConnect is called during a connection attempt after a successful authentication with the PostgreSQL server.
	// It can be used to validate that the server is acceptable. If this returns an error the connection is closed and the next
	// fallback config is tried. This allows implementing high availability behavior such as libpq does with target_session_attrs.
	ValidateConnect ValidateConnectFunc

	// AfterConnect is called after ValidateConnect. It can be used to set up the connection (e.g. Set session variables
	// or prepare statements). If this returns an error the connection attempt fails.
	AfterConnect AfterConnectFunc

	// OnNotice is a callback function called when a notice response is received.
	OnNotice NoticeHandler

	// OnNotification is a callback function called when a notification from the LISTEN/NOTIFY system is received.
	OnNotification NotificationHandler

	// OnPgError is a callback function called when a Postgres error is received by the server. The default handler will close
	// the connection on any FATAL errors. If you override this handler you should call the previously set handler or ensure
	// that you close on FATAL errors by returning false.
	OnPgError PgErrorHandler
	// contains filtered or unexported fields
}

Config is the settings used to establish a connection to a PostgreSQL server. It must be created by ParseConfig. A manually initialized Config will cause ConnectConfig to panic.

func ParseConfig 

func ParseConfig(connString string) (*Config, error)

ParseConfig builds a *Config from connString with similar behavior to the PostgreSQL standard C library libpq. It uses the same defaults as libpq (e.g. port=5432) and understands most PG* environment variables. ParseConfig closely matches the parsing behavior of libpq. connString may either be in URL format or keyword = value format. See https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING for details. connString also may be empty to only read from the environment. If a password is not supplied it will attempt to read the .pgpass file. 

# Example Keyword/Value
user=jack password=secret host=pg.example.com port=5432 dbname=mydb sslmode=verify-ca

# Example URL
postgres://jack:secret@pg.example.com:5432/mydb?sslmode=verify-ca

The returned *Config may be modified. However, it is strongly recommended that any configuration that can be done through the connection string be done there. In particular the fields Host, Port, TLSConfig, and Fallbacks can be interdependent (e.g. TLSConfig needs knowledge of the host to validate the server certificate). These fields should not be modified individually. They should all be modified or all left unchanged.

ParseConfig supports specifying multiple hosts in similar manner to libpq. Host and port may include comma separated values that will be tried in order. This can be used as part of a high availability system. See https://www.postgresql.org/docs/11/libpq-connect.html#LIBPQ-MULTIPLE-HOSTS for more information. 

# Example URL
postgres://jack:secret@foo.example.com:5432,bar.example.com:5432/mydb

ParseConfig currently recognizes the following environment variable and their parameter key word equivalents passed via database URL or keyword/value: 

PGHOST
PGPORT
PGDATABASE
PGUSER
PGPASSWORD
PGPASSFILE
PGSERVICE
PGSERVICEFILE
PGSSLMODE
PGSSLCERT
PGSSLKEY
PGSSLROOTCERT
PGSSLPASSWORD
PGAPPNAME
PGCONNECT_TIMEOUT
PGTARGETSESSIONATTRS

See http://www.postgresql.org/docs/11/static/libpq-envars.html for details on the meaning of environment variables.

See https://www.postgresql.org/docs/11/libpq-connect.html#LIBPQ-PARAMKEYWORDS for parameter key word names. They are usually but not always the environment variable name downcased and without the "PG" prefix.

Important Security Notes:

ParseConfig tries to match libpq behavior with regard to PGSSLMODE. This includes defaulting to "prefer" behavior if not set.

See http://www.postgresql.org/docs/11/static/libpq-ssl.html#LIBPQ-SSL-PROTECTION for details on what level of security each sslmode provides.

The sslmode "prefer" (the default), sslmode "allow", and multiple hosts are implemented via the Fallbacks field of the Config struct. If TLSConfig is manually changed it will not affect the fallbacks. For example, in the case of sslmode "prefer" this means it will first try the main Config settings which use TLS, then it will try the fallback which does not use TLS. This can lead to an unexpected unencrypted connection if the main TLS config is manually changed later but the unencrypted fallback is present. Ensure there are no stale fallbacks when manually setting TLSConfig.

Other known differences with libpq:

When multiple hosts are specified, libpq allows them to have different passwords set via the .pgpass file. pgconn does not.

In addition, ParseConfig accepts the following options:

  • servicefile. libpq only reads servicefile from the PGSERVICEFILE environment variable. ParseConfig accepts servicefile as a part of the connection string.

func ParseConfigWithOptions 

func ParseConfigWithOptions(connString string, options ParseConfigOptions) (*Config, error)

ParseConfigWithOptions builds a *Config from connString and options with similar behavior to the PostgreSQL standard C library libpq. options contains settings that cannot be specified in a connString such as providing a function to get the SSL password.

func (*Config) Copy 

func (c *Config) Copy() *Config

Copy returns a deep copy of the config that is safe to use and modify. The only exception is the TLSConfig field: according to the tls.Config docs it must not be modified after creation.

type ConnectError 

type ConnectError struct {
	Config *Config // The configuration that was used in the connection attempt.
	// contains filtered or unexported fields
}

ConnectError is the error returned when a connection attempt fails.

func (*ConnectError) Error 

func (e *ConnectError) Error() string

func (*ConnectError) Unwrap 

func (e *ConnectError) Unwrap() error

type DeadlineContextWatcherHandler 

type DeadlineContextWatcherHandler struct {
	Conn net.Conn

	// DeadlineDelay is the delay to set on the deadline set on net.Conn when the context is canceled.
	DeadlineDelay time.Duration
}

DeadlineContextWatcherHandler handles canceled contexts by setting a deadline on a net.Conn.

func (*DeadlineContextWatcherHandler) HandleCancel 

func (h *DeadlineContextWatcherHandler) HandleCancel(ctx context.Context)

func (*DeadlineContextWatcherHandler) HandleUnwatchAfterCancel 

func (h *DeadlineContextWatcherHandler) HandleUnwatchAfterCancel()

type DialFunc 

type DialFunc func(ctx context.Context, network, addr string) (net.Conn, error)

DialFunc is a function that can be used to connect to a PostgreSQL server.

type FallbackConfig 

type FallbackConfig struct {
	Host      string // host (e.g. localhost) or path to unix domain socket directory (e.g. /private/tmp)
	Port      uint16
	TLSConfig *tls.Config // nil disables TLS
}

FallbackConfig is additional settings to attempt a connection with when the primary Config fails to establish a network connection. It is used for TLS fallback such as sslmode=prefer and high availability (HA) connections.

type FieldDescription 

type FieldDescription struct {
	Name                 string
	TableOID             uint32
	TableAttributeNumber uint16
	DataTypeOID          uint32
	DataTypeSize         int16
	TypeModifier         int32
	Format               int16
}

type GSS 

type GSS interface {
	GetInitToken(host string, service string) ([]byte, error)
	GetInitTokenFromSPN(spn string) ([]byte, error)
	Continue(inToken []byte) (done bool, outToken []byte, err error)
}

GSS provides GSSAPI authentication (e.g., Kerberos).

type GetSSLPasswordFunc 

type GetSSLPasswordFunc func(ctx context.Context) string

type HijackedConn 

type HijackedConn struct {
	Conn              net.Conn
	PID               uint32            // backend pid
	SecretKey         uint32            // key to use to send a cancel query message to the server
	ParameterStatuses map[string]string // parameters that have been reported by the server
	TxStatus          byte
	Frontend          *pgproto3.Frontend
	Config            *Config
	CustomData        map[string]any
}

HijackedConn is the result of hijacking a connection.

Due to the necessary exposure of internal implementation details, it is not covered by the semantic versioning compatibility.

type LookupFunc 

type LookupFunc func(ctx context.Context, host string) (addrs []string, err error)

LookupFunc is a function that can be used to lookup IPs addrs from host. Optionally an ip:port combination can be returned in order to override the connection string's port.

type MultiResultReader 

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

MultiResultReader is a reader for a command that could return multiple results such as Exec or ExecBatch.

func (*MultiResultReader) Close 

func (mrr *MultiResultReader) Close() error

Close closes the MultiResultReader and returns the first error that occurred during the MultiResultReader's use.

func (*MultiResultReader) NextResult 

func (mrr *MultiResultReader) NextResult() bool

NextResult returns advances the MultiResultReader to the next result and returns true if a result is available.

func (*MultiResultReader) ReadAll 

func (mrr *MultiResultReader) ReadAll() ([]*Result, error)

ReadAll reads all available results. Calling ReadAll is mutually exclusive with all other MultiResultReader methods.

func (*MultiResultReader) ResultReader 

func (mrr *MultiResultReader) ResultReader() *ResultReader

ResultReader returns the current ResultReader.

type NewGSSFunc 

type NewGSSFunc func() (GSS, error)

NewGSSFunc creates a GSS authentication provider, for use with RegisterGSSProvider.

type NotPreferredError 

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

func (*NotPreferredError) Error 

func (e *NotPreferredError) Error() string

func (*NotPreferredError) SafeToRetry 

func (e *NotPreferredError) SafeToRetry() bool

func (*NotPreferredError) Unwrap 

func (e *NotPreferredError) Unwrap() error

type Notice 

type Notice PgError

Notice represents a notice response message reported by the PostgreSQL server. Be aware that this is distinct from LISTEN/NOTIFY notification.

type NoticeHandler 

type NoticeHandler func(*PgConn, *Notice)

NoticeHandler is a function that can handle notices received from the PostgreSQL server. Notices can be received at any time, usually during handling of a query response. The *PgConn is provided so the handler is aware of the origin of the notice, but it must not invoke any query method. Be aware that this is distinct from LISTEN/NOTIFY notification.

type Notification 

type Notification struct {
	PID     uint32 // backend pid that sent the notification
	Channel string // channel from which notification was received
	Payload string
}

Notification is a message received from the PostgreSQL LISTEN/NOTIFY system

type NotificationHandler 

type NotificationHandler func(*PgConn, *Notification)

NotificationHandler is a function that can handle notifications received from the PostgreSQL server. Notifications can be received at any time, usually during handling of a query response. The *PgConn is provided so the handler is aware of the origin of the notice, but it must not invoke any query method. Be aware that this is distinct from a notice event.

type ParseConfigError 

type ParseConfigError struct {
	ConnString string // The connection string that could not be parsed.
	// contains filtered or unexported fields
}

ParseConfigError is the error returned when a connection string cannot be parsed.

func (*ParseConfigError) Error 

func (e *ParseConfigError) Error() string

func (*ParseConfigError) Unwrap 

func (e *ParseConfigError) Unwrap() error

type ParseConfigOptions 

type ParseConfigOptions struct {
	// GetSSLPassword gets the password to decrypt a SSL client certificate. This is analogous to the libpq function
	// PQsetSSLKeyPassHook_OpenSSL.
	GetSSLPassword GetSSLPasswordFunc
}

ParseConfigOptions contains options that control how a config is built such as GetSSLPassword.

type PgConn 

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

PgConn is a low-level PostgreSQL connection handle. It is not safe for concurrent usage.

func Connect 

func Connect(ctx context.Context, connString string) (*PgConn, error)

Connect establishes a connection to a PostgreSQL server using the environment and connString (in URL or keyword/value format) to provide configuration. See documentation for ParseConfig for details. ctx can be used to cancel a connect attempt.

func ConnectConfig 

func ConnectConfig(ctx context.Context, config *Config) (*PgConn, error)

Connect establishes a connection to a PostgreSQL server using config. config must have been constructed with ParseConfig. ctx can be used to cancel a connect attempt.

If config.Fallbacks are present they will sequentially be tried in case of error establishing network connection. An authentication error will terminate the chain of attempts (like libpq: https://www.postgresql.org/docs/11/libpq-connect.html#LIBPQ-MULTIPLE-HOSTS) and be returned as the error.

func ConnectWithOptions 

func ConnectWithOptions(ctx context.Context, connString string, parseConfigOptions ParseConfigOptions) (*PgConn, error)

Connect establishes a connection to a PostgreSQL server using the environment and connString (in URL or keyword/value format) and ParseConfigOptions to provide additional configuration. See documentation for ParseConfig for details. ctx can be used to cancel a connect attempt.

func Construct 

func Construct(hc *HijackedConn) (*PgConn, error)

Construct created a PgConn from an already established connection to a PostgreSQL server. This is the inverse of PgConn.Hijack. The connection must be in an idle state.

hc.Frontend is replaced by a new pgproto3.Frontend built by hc.Config.BuildFrontend.

Due to the necessary exposure of internal implementation details, it is not covered by the semantic versioning compatibility.

func (*PgConn) CancelRequest 

func (pgConn *PgConn) CancelRequest(ctx context.Context) error

CancelRequest sends a cancel request to the PostgreSQL server. It returns an error if unable to deliver the cancel request, but lack of an error does not ensure that the query was canceled. As specified in the documentation, there is no way to be sure a query was canceled. See https://www.postgresql.org/docs/11/protocol-flow.html#id-1.10.5.7.9

func (*PgConn) CheckConn deprecated 

func (pgConn *PgConn) CheckConn() error

CheckConn checks the underlying connection without writing any bytes. This is currently implemented by doing a read with a very short deadline. This can be useful because a TCP connection can be broken such that a write will appear to succeed even though it will never actually reach the server. Reading immediately before a write will detect this condition. If this is done immediately before sending a query it reduces the chances a query will be sent that fails without the client knowing whether the server received it or not.

Deprecated: CheckConn is deprecated in favor of Ping. CheckConn cannot detect all types of broken connections where the write would still appear to succeed. Prefer Ping unless on a high latency connection.

func (*PgConn) CleanupDone 

func (pgConn *PgConn) CleanupDone() chan (struct{})

CleanupDone returns a channel that will be closed after all underlying resources have been cleaned up. A closed connection is no longer usable, but underlying resources, in particular the net.Conn, may not have finished closing yet. This is because certain errors such as a context cancellation require that the interrupted function call return immediately, but the error may also cause the connection to be closed. In these cases the underlying resources are closed asynchronously.

This is only likely to be useful to connection pools. It gives them a way avoid establishing a new connection while an old connection is still being cleaned up and thereby exceeding the maximum pool size.

func (*PgConn) Close 

func (pgConn *PgConn) Close(ctx context.Context) error

Close closes a connection. It is safe to call Close on an already closed connection. Close attempts a clean close by sending the exit message to PostgreSQL. However, this could block so ctx is available to limit the time to wait. The underlying net.Conn.Close() will always be called regardless of any other errors.

func (*PgConn) Conn 

func (pgConn *PgConn) Conn() net.Conn

Conn returns the underlying net.Conn. This rarely necessary. If the connection will be directly used for reading or writing then SyncConn should usually be called before Conn.

func (*PgConn) CopyFrom 

func (pgConn *PgConn) CopyFrom(ctx context.Context, r io.Reader, sql string) (CommandTag, error)

CopyFrom executes the copy command sql and copies all of r to the PostgreSQL server.

Note: context cancellation will only interrupt operations on the underlying PostgreSQL network connection. Reads on r could still block.

func (*PgConn) CopyTo 

func (pgConn *PgConn) CopyTo(ctx context.Context, w io.Writer, sql string) (CommandTag, error)

CopyTo executes the copy command sql and copies the results to w.

func (*PgConn) CustomData 

func (pgConn *PgConn) CustomData() map[string]any

CustomData returns a map that can be used to associate custom data with the connection.

func (*PgConn) Deallocate 

func (pgConn *PgConn) Deallocate(ctx context.Context, name string) error

Deallocate deallocates a prepared statement.

Deallocate does not send a DEALLOCATE statement to the server. It uses the PostgreSQL Close protocol message directly. This has slightly different behavior than executing DEALLOCATE statement.

  • Deallocate can succeed in an aborted transaction.
  • Deallocating a non-existent prepared statement is not an error.

func (*PgConn) EscapeString 

func (pgConn *PgConn) EscapeString(s string) (string, error)

EscapeString escapes a string such that it can safely be interpolated into a SQL command string. It does not include the surrounding single quotes.

The current implementation requires that standard_conforming_strings=on and client_encoding="UTF8". If these conditions are not met an error will be returned. It is possible these restrictions will be lifted in the future.

func (*PgConn) Exec 

func (pgConn *PgConn) Exec(ctx context.Context, sql string) *MultiResultReader

Exec executes SQL via the PostgreSQL simple query protocol. SQL may contain multiple queries. Execution is implicitly wrapped in a transaction unless a transaction is already in progress or SQL contains transaction control statements.

Prefer ExecParams unless executing arbitrary SQL that may contain multiple queries.

func (*PgConn) ExecBatch 

func (pgConn *PgConn) ExecBatch(ctx context.Context, batch *Batch) *MultiResultReader

ExecBatch executes all the queries in batch in a single round-trip. Execution is implicitly transactional unless a transaction is already in progress or SQL contains transaction control statements. This is a simpler way of executing multiple queries in a single round trip than using pipeline mode.

func (*PgConn) ExecParams 

func (pgConn *PgConn) ExecParams(ctx context.Context, sql string, paramValues [][]byte, paramOIDs []uint32, paramFormats []int16, resultFormats []int16) *ResultReader

ExecParams executes a command via the PostgreSQL extended query protocol.

sql is a SQL command string. It may only contain one query. Parameter substitution is positional using $1, $2, $3, etc.

paramValues are the parameter values. It must be encoded in the format given by paramFormats.

paramOIDs is a slice of data type OIDs for paramValues. If paramOIDs is nil, the server will infer the data type for all parameters. Any paramOID element that is 0 that will cause the server to infer the data type for that parameter. ExecParams will panic if len(paramOIDs) is not 0, 1, or len(paramValues).

paramFormats is a slice of format codes determining for each paramValue column whether it is encoded in text or binary format. If paramFormats is nil all params are text format. ExecParams will panic if len(paramFormats) is not 0, 1, or len(paramValues).

resultFormats is a slice of format codes determining for each result column whether it is encoded in text or binary format. If resultFormats is nil all results will be in text format.

ResultReader must be closed before PgConn can be used again.

func (*PgConn) ExecPrepared 

func (pgConn *PgConn) ExecPrepared(ctx context.Context, stmtName string, paramValues [][]byte, paramFormats []int16, resultFormats []int16) *ResultReader

ExecPrepared enqueues the execution of a prepared statement via the PostgreSQL extended query protocol.

paramValues are the parameter values. It must be encoded in the format given by paramFormats.

paramFormats is a slice of format codes determining for each paramValue column whether it is encoded in text or binary format. If paramFormats is nil all params are text format. ExecPrepared will panic if len(paramFormats) is not 0, 1, or len(paramValues).

resultFormats is a slice of format codes determining for each result column whether it is encoded in text or binary format. If resultFormats is nil all results will be in text format.

ResultReader must be closed before PgConn can be used again.

func (*PgConn) Frontend 

func (pgConn *PgConn) Frontend() *pgproto3.Frontend

Frontend returns the underlying *pgproto3.Frontend. This rarely necessary.

func (*PgConn) Hijack 

func (pgConn *PgConn) Hijack() (*HijackedConn, error)

Hijack extracts the internal connection data. pgConn must be in an idle state. SyncConn should be called immediately before Hijack. pgConn is unusable after hijacking. Hijacking is typically only useful when using pgconn to establish a connection, but taking complete control of the raw connection after that (e.g. a load balancer or proxy).

Due to the necessary exposure of internal implementation details, it is not covered by the semantic versioning compatibility.

func (*PgConn) IsBusy 

func (pgConn *PgConn) IsBusy() bool

IsBusy reports if the connection is busy.

func (*PgConn) IsClosed 

func (pgConn *PgConn) IsClosed() bool

IsClosed reports if the connection has been closed.

CleanupDone() can be used to determine if all cleanup has been completed.

func (*PgConn) PID 

func (pgConn *PgConn) PID() uint32

PID returns the backend PID.

func (*PgConn) ParameterStatus 

func (pgConn *PgConn) ParameterStatus(key string) string

ParameterStatus returns the value of a parameter reported by the server (e.g. server_version). Returns an empty string for unknown parameters.

func (*PgConn) Ping 

func (pgConn *PgConn) Ping(ctx context.Context) error

Ping pings the server. This can be useful because a TCP connection can be broken such that a write will appear to succeed even though it will never actually reach the server. Pinging immediately before sending a query reduces the chances a query will be sent that fails without the client knowing whether the server received it or not.

func (*PgConn) Prepare 

func (pgConn *PgConn) Prepare(ctx context.Context, name, sql string, paramOIDs []uint32) (*StatementDescription, error)

Prepare creates a prepared statement. If the name is empty, the anonymous prepared statement will be used. This allows Prepare to also to describe statements without creating a server-side prepared statement.

Prepare does not send a PREPARE statement to the server. It uses the PostgreSQL Parse and Describe protocol messages directly.

func (*PgConn) ReceiveMessage 

func (pgConn *PgConn) ReceiveMessage(ctx context.Context) (pgproto3.BackendMessage, error)

ReceiveMessage receives one wire protocol message from the PostgreSQL server. It must only be used when the connection is not busy. e.g. It is an error to call ReceiveMessage while reading the result of a query. The messages are still handled by the core pgconn message handling system so receiving a NotificationResponse will still trigger the OnNotification callback.

This is a very low level method that requires deep understanding of the PostgreSQL wire protocol to use correctly. See https://www.postgresql.org/docs/current/protocol.html.

func (*PgConn) SecretKey 

func (pgConn *PgConn) SecretKey() uint32

SecretKey returns the backend secret key used to send a cancel query message to the server.

func (*PgConn) StartPipeline 

func (pgConn *PgConn) StartPipeline(ctx context.Context) *Pipeline

StartPipeline switches the connection to pipeline mode and returns a *Pipeline. In pipeline mode requests can be sent to the server without waiting for a response. Close must be called on the returned *Pipeline to return the connection to normal mode. While in pipeline mode, no methods that communicate with the server may be called except CancelRequest and Close. ctx is in effect for entire life of the *Pipeline.

Prefer ExecBatch when only sending one group of queries at once.

func (*PgConn) SyncConn 

func (pgConn *PgConn) SyncConn(ctx context.Context) error

SyncConn prepares the underlying net.Conn for direct use. PgConn may internally buffer reads or use goroutines for background IO. This means that any direct use of the underlying net.Conn may be corrupted if a read is already buffered or a read is in progress. SyncConn drains read buffers and stops background IO. In some cases this may require sending a ping to the server. ctx can be used to cancel this operation. This should be called before any operation that will use the underlying net.Conn directly. e.g. Before Conn() or Hijack().

This should not be confused with the PostgreSQL protocol Sync message.

func (*PgConn) TxStatus 

func (pgConn *PgConn) TxStatus() byte

TxStatus returns the current TxStatus as reported by the server in the ReadyForQuery message.

Possible return values: 

'I' - idle / not in transaction
'T' - in a transaction
'E' - in a failed transaction

See https://www.postgresql.org/docs/current/protocol-message-formats.html.

func (*PgConn) WaitForNotification 

func (pgConn *PgConn) WaitForNotification(ctx context.Context) error

WaitForNotification waits for a LISTEN/NOTIFY message to be received. It returns an error if a notification was not received.

type PgError 

type PgError struct {
	Severity            string
	SeverityUnlocalized string
	Code                string
	Message             string
	Detail              string
	Hint                string
	Position            int32
	InternalPosition    int32
	InternalQuery       string
	Where               string
	SchemaName          string
	TableName           string
	ColumnName          string
	DataTypeName        string
	ConstraintName      string
	File                string
	Line                int32
	Routine             string
}

PgError represents an error reported by the PostgreSQL server. See http://www.postgresql.org/docs/11/static/protocol-error-fields.html for detailed field description.

func ErrorResponseToPgError 

func ErrorResponseToPgError(msg *pgproto3.ErrorResponse) *PgError

ErrorResponseToPgError converts a wire protocol error message to a *PgError.

func (*PgError) Error 

func (pe *PgError) Error() string

func (*PgError) SQLState 

func (pe *PgError) SQLState() string

SQLState returns the SQLState of the error.

type PgErrorHandler 

type PgErrorHandler func(*PgConn, *PgError) bool

PgErrorHandler is a function that handles errors returned from Postgres. This function must return true to keep the connection open. Returning false will cause the connection to be closed immediately. You should return false on any FATAL-severity errors. This will not receive network errors. The *PgConn is provided so the handler is aware of the origin of the error, but it must not invoke any query method.

type Pipeline 

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

Pipeline represents a connection in pipeline mode.

SendPrepare, SendQueryParams, and SendQueryPrepared queue requests to the server. These requests are not written until pipeline is flushed by Flush or Sync. Sync must be called after the last request is queued. Requests between synchronization points are implicitly transactional unless explicit transaction control statements have been issued.

The context the pipeline was started with is in effect for the entire life of the Pipeline.

For a deeper understanding of pipeline mode see the PostgreSQL documentation for the extended query protocol (https://www.postgresql.org/docs/current/protocol-flow.html#PROTOCOL-FLOW-EXT-QUERY) and the libpq pipeline mode (https://www.postgresql.org/docs/current/libpq-pipeline-mode.html).

func (*Pipeline) Close 

func (p *Pipeline) Close() error

Close closes the pipeline and returns the connection to normal mode.

func (*Pipeline) Flush 

func (p *Pipeline) Flush() error

Flush flushes the queued requests without establishing a synchronization point.

func (*Pipeline) GetResults 

func (p *Pipeline) GetResults() (results any, err error)

GetResults gets the next results. If results are present, results may be a *ResultReader, *StatementDescription, or *PipelineSync. If an ErrorResponse is received from the server, results will be nil and err will be a *PgError. If no results are available, results and err will both be nil.

func (*Pipeline) SendDeallocate 

func (p *Pipeline) SendDeallocate(name string)

SendDeallocate deallocates a prepared statement.

func (*Pipeline) SendPrepare 

func (p *Pipeline) SendPrepare(name, sql string, paramOIDs []uint32)

SendPrepare is the pipeline version of *PgConn.Prepare.

func (*Pipeline) SendQueryParams 

func (p *Pipeline) SendQueryParams(sql string, paramValues [][]byte, paramOIDs []uint32, paramFormats []int16, resultFormats []int16)

SendQueryParams is the pipeline version of *PgConn.QueryParams.

func (*Pipeline) SendQueryPrepared 

func (p *Pipeline) SendQueryPrepared(stmtName string, paramValues [][]byte, paramFormats []int16, resultFormats []int16)

SendQueryPrepared is the pipeline version of *PgConn.QueryPrepared.

func (*Pipeline) Sync 

func (p *Pipeline) Sync() error

Sync establishes a synchronization point and flushes the queued requests.

type PipelineSync 

type PipelineSync struct{}

PipelineSync is returned by GetResults when a ReadyForQuery message is received.

type Result 

type Result struct {
	FieldDescriptions []FieldDescription
	Rows              [][][]byte
	CommandTag        CommandTag
	Err               error
}

Result is the saved query response that is returned by calling Read on a ResultReader.

type ResultReader 

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

ResultReader is a reader for the result of a single query.

func (*ResultReader) Close 

func (rr *ResultReader) Close() (CommandTag, error)

Close consumes any remaining result data and returns the command tag or error.

func (*ResultReader) FieldDescriptions 

func (rr *ResultReader) FieldDescriptions() []FieldDescription

FieldDescriptions returns the field descriptions for the current result set. The returned slice is only valid until the ResultReader is closed. It may return nil (for example, if the query did not return a result set or an error was encountered.)

func (*ResultReader) NextRow 

func (rr *ResultReader) NextRow() bool

NextRow advances the ResultReader to the next row and returns true if a row is available.

func (*ResultReader) Read 

func (rr *ResultReader) Read() *Result

Read saves the query response to a Result.

func (*ResultReader) Values 

func (rr *ResultReader) Values() [][]byte

Values returns the current row data. NextRow must have been previously been called. The returned [][]byte is only valid until the next NextRow call or the ResultReader is closed.

type StatementDescription 

type StatementDescription struct {
	Name      string
	SQL       string
	ParamOIDs []uint32
	Fields    []FieldDescription
}

type ValidateConnectFunc 

type ValidateConnectFunc func(ctx context.Context, pgconn *PgConn) error

Source Files

View all Source files

Directories

Path Synopsis
internal
bgreader
Package bgreader provides a io.Reader that can optionally buffer reads in the background.
 Package bgreader provides a io.Reader that can optionally buffer reads in the background.

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