tidb

README

What is TiDB?

TiDB (The pronunciation is: /'taɪdiːbi:/ tai-D-B, etymology: titanium) is a Hybrid Transactional/Analytical Processing (HTAP) database. Inspired by the design of Google F1 and Google Spanner, TiDB features infinite horizontal scalability, strong consistency, and high availability. The goal of TiDB is to serve as a one-stop solution for online transactions and analyses.

• Horizontal scalability

Grow TiDB as your business grows. You can increase the capacity for storage and computation simply by adding more machines.

• Compatible with MySQL protocol

Use TiDB as MySQL. You can replace MySQL with TiDB to power your application without changing a single line of code in most cases.

• Automatic Failover and high availability

Your data and applications are always-on. TiDB automatically handles malfunctions and protects your applications from machine failures or even downtime of an entire data-center.

• Consistent distributed transactions

Think of TiDB as a single-machine RDBMS. You can start a transaction that crosses multiple machines without worrying about consistency. TiDB makes your application code simple and robust.

• Online DDL

Evolve TiDB schemas as your requirement changes. You can add new columns and indexes without stopping or affecting the on-going operations.

• Multiple storage engine support

Power TiDB with your most favorite engines. TiDB supports local storage engines such as GolevelDB and BoltDB, as well as TiKV, a distributed storage engine.

For more details, see How we build TiDB.

Roadmap

Read the Roadmap.

Quick start

Read the Quick Start.

Documentation

• English
• 简体中文

Architecture

Contributing

Contributions are welcomed and greatly appreciated. See CONTRIBUTING.md for details on submitting patches and the contribution workflow.

Follow us

Twitter

@PingCAP

Mailing list

tidb-user@googlegroups.com

Google Group

License

TiDB is under the Apache 2.0 license. See the LICENSE file for details.

Acknowledgments

• Thanks cznic for providing some great open source tools.
• Thanks GolevelDB, BoltDB, and RocksDB for their powerful storage engines.

Documentation

Index

• Constants
• Variables
• func BootstrapSession(store kv.Storage) (*domain.Domain, error)
• func Compile(ctx context.Context, stmtNode ast.StmtNode) (ast.Statement, error)
• func GetRows(rs ast.RecordSet) ([][]types.Datum, error)
• func IsQuery(sql string) bool
• func NewStore(path string) (kv.Storage, error)
• func Parse(ctx context.Context, src string) ([]ast.StmtNode, error)
• func RegisterLocalStore(name string, driver engine.Driver) error
• func RegisterStore(name string, driver kv.Driver) error
• func SetCommitRetryLimit(limit int)
• func SetSchemaLease(lease time.Duration)
• func SetStatsLease(lease time.Duration)
• type PreCommitHook
  • func (h PreCommitHook) String() string
• type Session
  • func CreateSession(store kv.Storage) (Session, error)
• type StmtHistory
  • func GetHistory(ctx context.Context) *StmtHistory
  • func (h *StmtHistory) Add(stmtID uint32, st ast.Statement, stmtCtx *variable.StatementContext, ...)

Constants

const (
	// CreateUserTable is the SQL statement creates User table in system db.
	CreateUserTable = `` /* 1365-byte string literal not displayed */

	// CreateDBPrivTable is the SQL statement creates DB scope privilege table in system db.
	CreateDBPrivTable = `` /* 1127-byte string literal not displayed */

	// CreateTablePrivTable is the SQL statement creates table scope privilege table in system db.
	CreateTablePrivTable = `` /* 380-byte string literal not displayed */

	// CreateColumnPrivTable is the SQL statement creates column scope privilege table in system db.
	CreateColumnPrivTable = `` /* 300-byte string literal not displayed */

	// CreateGloablVariablesTable is the SQL statement creates global variable table in system db.
	// TODO: MySQL puts GLOBAL_VARIABLES table in INFORMATION_SCHEMA db.
	// INFORMATION_SCHEMA is a virtual db in TiDB. So we put this table in system db.
	// Maybe we will put it back to INFORMATION_SCHEMA.
	CreateGloablVariablesTable = `` /* 147-byte string literal not displayed */

	// CreateTiDBTable is the SQL statement creates a table in system db.
	// This table is a key-value struct contains some information used by TiDB.
	// Currently we only put bootstrapped in it which indicates if the system is already bootstrapped.
	CreateTiDBTable = `` /* 160-byte string literal not displayed */

	// CreateHelpTopic is the SQL statement creates help_topic table in system db.
	// See: https://dev.mysql.com/doc/refman/5.5/en/system-database.html#system-database-help-tables
	CreateHelpTopic = `` /* 392-byte string literal not displayed */

	// CreateStatsMetaTable stores the meta of table statistics.
	CreateStatsMetaTable = `` /* 270-byte string literal not displayed */

	// CreateStatsColsTable stores the statistics of table columns.
	CreateStatsColsTable = `` /* 376-byte string literal not displayed */

	// CreateStatsBucketsTable stores the histogram info for every table columns.
	CreateStatsBucketsTable = `` /* 349-byte string literal not displayed */

	// CreateGCDeleteRangeTable stores schemas which can be deleted by DeleteRange.
	CreateGCDeleteRangeTable = `` /* 390-byte string literal not displayed */

)

const (
	EngineGoLevelDBMemory = "memory://"
)

Engine prefix name

Variables

var (
	// SchemaOutOfDateRetryInterval is the sleeping time when we fail to try.
	SchemaOutOfDateRetryInterval = int64(500 * time.Millisecond)
	// SchemaOutOfDateRetryTimes is upper bound of retry times when the schema is out of date.
	SchemaOutOfDateRetryTimes = int32(10)
)

var SchemaChangedWithoutRetry bool

SchemaChangedWithoutRetry is used for testing.

Functions

func BootstrapSession

func BootstrapSession(store kv.Storage) (*domain.Domain, error)

BootstrapSession runs the first time when the TiDB server start.

func Compile

func Compile(ctx context.Context, stmtNode ast.StmtNode) (ast.Statement, error)

Compile is safe for concurrent use by multiple goroutines.

func GetRows

func GetRows(rs ast.RecordSet) ([][]types.Datum, error)

GetRows gets all the rows from a RecordSet.

func IsQuery

func IsQuery(sql string) bool

IsQuery checks if a sql statement is a query statement.

func NewStore

func NewStore(path string) (kv.Storage, error)

NewStore creates a kv Storage with path.

The path must be a URL format 'engine://path?params' like the one for tidb.Open() but with the dbname cut off. Examples:

goleveldb://relative/path
boltdb:///absolute/path

The engine should be registered before creating storage.

func Parse

func Parse(ctx context.Context, src string) ([]ast.StmtNode, error)

Parse parses a query string to raw ast.StmtNode.

func RegisterLocalStore

func RegisterLocalStore(name string, driver engine.Driver) error

RegisterLocalStore registers a local kv storage with unique name and its associated engine Driver.

func RegisterStore

func RegisterStore(name string, driver kv.Driver) error

RegisterStore registers a kv storage with unique name and its associated Driver.

func SetCommitRetryLimit

func SetCommitRetryLimit(limit int)

SetCommitRetryLimit setups the maximum number of retries when trying to recover from retryable errors. Retryable errors are generally refer to temporary errors that are expected to be reinstated by retry, including network interruption, transaction conflicts, and so on.

func SetSchemaLease

func SetSchemaLease(lease time.Duration)

SetSchemaLease changes the default schema lease time for DDL. This function is very dangerous, don't use it if you really know what you do. SetSchemaLease only affects not local storage after bootstrapped.

func SetStatsLease

func SetStatsLease(lease time.Duration)

SetStatsLease changes the default stats lease time for loading stats info.

Types

type PreCommitHook

type PreCommitHook struct{}

PreCommitHook implements the fmt.Stringer interface.

func (PreCommitHook) String

func (h PreCommitHook) String() string

type Session

type Session interface {
	context.Context
	Status() uint16                              // Flag of current status, such as autocommit.
	LastInsertID() uint64                        // LastInsertID is the last inserted auto_increment ID.
	AffectedRows() uint64                        // Affected rows by latest executed stmt.
	Execute(sql string) ([]ast.RecordSet, error) // Execute a sql statement.
	String() string                              // String is used to debug.
	CommitTxn() error
	RollbackTxn() error
	// PrepareStmt executes prepare statement in binary protocol.
	PrepareStmt(sql string) (stmtID uint32, paramCount int, fields []*ast.ResultField, err error)
	// ExecutePreparedStmt executes a prepared statement.
	ExecutePreparedStmt(stmtID uint32, param ...interface{}) (ast.RecordSet, error)
	DropPreparedStmt(stmtID uint32) error
	SetClientCapability(uint32) // Set client capability flags.
	SetConnectionID(uint64)
	SetTLSState(*tls.ConnectionState)
	SetCollation(coID int) error
	SetSessionManager(util.SessionManager)
	Close()
	Auth(user *auth.UserIdentity, auth []byte, salt []byte) bool
	// Cancel the execution of current transaction.
	Cancel()
	ShowProcess() util.ProcessInfo
	// PrePareTxnCtx is exported for test.
	PrepareTxnCtx()
}

Session context

func CreateSession

func CreateSession(store kv.Storage) (Session, error)

CreateSession creates a new session environment.

type StmtHistory

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

StmtHistory holds all histories of statements in a txn.

func GetHistory

func GetHistory(ctx context.Context) *StmtHistory

GetHistory get all stmtHistory in current txn. Exported only for test.

func (*StmtHistory) Add

func (h *StmtHistory) Add(stmtID uint32, st ast.Statement, stmtCtx *variable.StatementContext, params ...interface{})

Add appends a stmt to history list.