sessionctx

Documentation

Index

• Constants
• func ValidateSnapshotReadTS(ctx context.Context, store kv.Storage, readTS uint64, isStaleRead bool) error
• type Context
• type InstancePlanCache
• type SessionPlanCache
• type SessionStatesHandler
• type TxnFuture

Constants

const (
	// QueryString is the key for original query string.
	QueryString basicCtxType = 1
	// Initing is the key for indicating if the server is running bootstrap or upgrade job.
	Initing basicCtxType = 2
	// LastExecuteDDL is the key for whether the session execute a ddl command last time.
	LastExecuteDDL basicCtxType = 3
)

Context keys.

Functions

func ValidateSnapshotReadTS

func ValidateSnapshotReadTS(ctx context.Context, store kv.Storage, readTS uint64, isStaleRead bool) error

ValidateSnapshotReadTS strictly validates that readTS does not exceed the PD timestamp. For read requests to the storage, the check can be implicitly performed when sending the RPC request. So this function is only needed when it's not proper to delay the check to when RPC requests are being sent (e.g., `BEGIN` statements that don't make reading operation immediately).

Types

type Context

type Context interface {
	SessionStatesHandler
	contextutil.ValueStoreContext
	tablelock.TableLockContext
	// RollbackTxn rolls back the current transaction.
	RollbackTxn(ctx context.Context)
	// CommitTxn commits the current transaction.
	// buffered KV changes will be discarded, call StmtCommit if you want to commit them.
	CommitTxn(ctx context.Context) error
	// Txn returns the current transaction which is created before executing a statement.
	// The returned kv.Transaction is not nil, but it maybe pending or invalid.
	// If the active parameter is true, call this function will wait for the pending txn
	// to become valid.
	Txn(active bool) (kv.Transaction, error)

	// GetClient gets a kv.Client.
	GetClient() kv.Client

	// GetMPPClient gets a kv.MPPClient.
	GetMPPClient() kv.MPPClient

	// Deprecated: the semantics of session.GetInfoSchema() is ambiguous
	// If you want to get the infoschema of the current transaction in SQL layer, use sessiontxn.GetTxnManager(ctx).GetTxnInfoSchema()
	// If you want to get the latest infoschema use `GetDomainInfoSchema`
	GetInfoSchema() infoschema.MetaOnlyInfoSchema

	// GetDomainInfoSchema returns the latest information schema in domain
	// Different with `domain.InfoSchema()`, the information schema returned by this method
	// includes the temporary table definitions stored in session
	GetDomainInfoSchema() infoschema.MetaOnlyInfoSchema

	GetSessionVars() *variable.SessionVars

	// GetSQLExecutor returns the sqlexec.SQLExecutor.
	GetSQLExecutor() sqlexec.SQLExecutor

	// GetRestrictedSQLExecutor returns the sqlexec.RestrictedSQLExecutor.
	GetRestrictedSQLExecutor() sqlexec.RestrictedSQLExecutor

	// GetExprCtx returns the expression context of the session.
	GetExprCtx() exprctx.ExprContext

	// GetTableCtx returns the table.MutateContext
	GetTableCtx() tblctx.MutateContext

	// GetPlanCtx gets the plan context of the current session.
	GetPlanCtx() planctx.PlanContext

	// GetDistSQLCtx gets the distsql ctx of the current session
	GetDistSQLCtx() *distsqlctx.DistSQLContext

	// GetRangerCtx returns the context used in `ranger` related functions
	GetRangerCtx() *rangerctx.RangerContext

	// GetBuildPBCtx gets the ctx used in `ToPB` of the current session
	GetBuildPBCtx() *planctx.BuildPBContext

	GetSessionManager() util.SessionManager

	// RefreshTxnCtx commits old transaction without retry,
	// and creates a new transaction.
	// now just for load data and batch insert.
	RefreshTxnCtx(context.Context) error

	// GetStore returns the store of session.
	GetStore() kv.Storage

	// GetSessionPlanCache returns the session-level cache of the physical plan.
	GetSessionPlanCache() SessionPlanCache

	// UpdateColStatsUsage updates the column stats usage.
	UpdateColStatsUsage(predicateColumns iter.Seq[model.TableItemID])

	// HasDirtyContent checks whether there's dirty update on the given table.
	HasDirtyContent(tid int64) bool

	// StmtCommit flush all changes by the statement to the underlying transaction.
	// it must be called before CommitTxn, else all changes since last StmtCommit
	// will be lost. For SQL statement, StmtCommit or StmtRollback is called automatically.
	// the "Stmt" not only means SQL statement, but also any KV changes, such as
	// meta KV.
	StmtCommit(ctx context.Context)
	// StmtRollback provides statement level rollback. The parameter `forPessimisticRetry` should be true iff it's used
	// for auto-retrying execution of DMLs in pessimistic transactions.
	// if error happens when you are handling batch of KV changes since last StmtCommit
	// or StmtRollback, and you don't want them to be committed, you must call StmtRollback
	// before you start another batch, otherwise, the previous changes might be committed
	// unexpectedly.
	StmtRollback(ctx context.Context, isForPessimisticRetry bool)
	// IsDDLOwner checks whether this session is DDL owner.
	IsDDLOwner() bool
	// PrepareTSFuture uses to prepare timestamp by future.
	PrepareTSFuture(ctx context.Context, future oracle.Future, scope string) error
	// GetPreparedTxnFuture returns the TxnFuture if it is valid or pending.
	// It returns nil otherwise.
	GetPreparedTxnFuture() TxnFuture
	// GetTxnWriteThroughputSLI returns the TxnWriteThroughputSLI.
	GetTxnWriteThroughputSLI() *sli.TxnWriteThroughputSLI
	// GetStmtStats returns stmtstats.StatementStats owned by implementation.
	GetStmtStats() *stmtstats.StatementStats
	// ShowProcess returns ProcessInfo running in current Context
	ShowProcess() *util.ProcessInfo
	// GetAdvisoryLock acquires an advisory lock (aka GET_LOCK()).
	GetAdvisoryLock(string, int64) error
	// IsUsedAdvisoryLock checks for existing locks (aka IS_USED_LOCK()).
	IsUsedAdvisoryLock(string) uint64
	// ReleaseAdvisoryLock releases an advisory lock (aka RELEASE_LOCK()).
	ReleaseAdvisoryLock(string) bool
	// ReleaseAllAdvisoryLocks releases all advisory locks that this session holds.
	ReleaseAllAdvisoryLocks() int
	// GetExtensions returns the `*extension.SessionExtensions` object
	GetExtensions() *extension.SessionExtensions
	// InSandBoxMode indicates that this Session is in sandbox mode
	// Ref about sandbox mode: https://dev.mysql.com/doc/refman/8.0/en/expired-password-handling.html
	InSandBoxMode() bool
	// EnableSandBoxMode enable the sandbox mode of this Session
	EnableSandBoxMode()
	// DisableSandBoxMode enable the sandbox mode of this Session
	DisableSandBoxMode()
	// ReportUsageStats reports the usage stats to the global collector
	ReportUsageStats()
	// NewStmtIndexUsageCollector creates a new index usage collector for statement
	NewStmtIndexUsageCollector() *indexusage.StmtIndexUsageCollector
	// GetCursorTracker returns the cursor tracker of the session
	GetCursorTracker() cursor.Tracker
	// GetCommitWaitGroup returns the wait group for async commit and secondary lock cleanup background goroutines
	GetCommitWaitGroup() *sync.WaitGroup
}

Context is an interface for transaction and executive args environment.

type InstancePlanCache

type InstancePlanCache interface {
	// Get gets the cached value from the cache according to key and opts.
	Get(key string, paramTypes any) (value any, ok bool)
	// Put puts the key and value into the cache.
	Put(key string, value, paramTypes any) (succ bool)
	// All returns all cached values.
	// Returned values are read-only, don't modify them.
	All() (values []any)
	// Evict evicts some cached values.
	Evict(evictAll bool) (detailInfo string, numEvicted int)
	// Size returns the number of cached values.
	Size() int64
	// MemUsage returns the total memory usage of this plan cache.
	MemUsage() int64
	// GetLimits returns the soft and hard memory limits of this plan cache.
	GetLimits() (softLimit, hardLimit int64)
	// SetLimits sets the soft and hard memory limits of this plan cache.
	SetLimits(softLimit, hardLimit int64)
}

InstancePlanCache represents the instance/node level plan cache. Value and Opts should always be *PlanCacheValue and *PlanCacheMatchOpts, use any to avoid cycle-import.

type SessionPlanCache

type SessionPlanCache interface {
	Get(key string, paramTypes any) (value any, ok bool)
	Put(key string, value, paramTypes any)
	Delete(key string)
	DeleteAll()
	Size() int
	SetCapacity(capacity uint) error
	Close()
}

SessionPlanCache is an interface for prepare and non-prepared plan cache

type SessionStatesHandler

type SessionStatesHandler interface {
	// EncodeSessionStates encodes session states into a JSON.
	EncodeSessionStates(context.Context, Context, *sessionstates.SessionStates) error
	// DecodeSessionStates decodes a map into session states.
	DecodeSessionStates(context.Context, Context, *sessionstates.SessionStates) error
}

SessionStatesHandler is an interface for encoding and decoding session states.

type TxnFuture

type TxnFuture interface {
	// Wait converts pending txn to valid
	Wait(ctx context.Context, sctx Context) (kv.Transaction, error)
}

TxnFuture is an interface where implementations have a kv.Transaction field and after calling Wait of the TxnFuture, the kv.Transaction will become valid.