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 Go to latest Published: Mar 22, 2018 License: Apache-2.0 Imports: 18 Imported by: 0

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Index

Constants

View Source 
const (
	SQLModeVar          = "sql_mode"
	AutocommitVar       = "autocommit"
	CharacterSetResults = "character_set_results"
	MaxAllowedPacket    = "max_allowed_packet"
	TimeZone            = "time_zone"
	TxnIsolation        = "tx_isolation"
)

special session variables.

View Source 
const (
	CodeUnknownStatusVar terror.ErrCode = 1
	CodeUnknownSystemVar terror.ErrCode = 1193
	CodeIncorrectScope   terror.ErrCode = 1238
	CodeUnknownTimeZone  terror.ErrCode = 1298
	CodeReadOnly         terror.ErrCode = 1621
)

Variable error codes.

View Source 
const (
	// CharacterSetConnection is the name for character_set_connection system variable.
	CharacterSetConnection = "character_set_connection"
	// CollationConnection is the name for collation_connection system variable.
	CollationConnection = "collation_connection"
	// CharsetDatabase is the name for character_set_database system variable.
	CharsetDatabase = "character_set_database"
	// CollationDatabase is the name for collation_database system variable.
	CollationDatabase = "collation_database"
)
View Source 
const (

	// tidb_snapshot is used for reading history data, the default value is empty string.
	// When the value is set to a datetime string like '2017-11-11 20:20:20', the session reads history data of that time.
	TiDBSnapshot = "tidb_snapshot"

	// tidb_import_data is used for loading data from a dump file, to speed up the loading process.
	// When the value is set to true, unique index constraint is not checked.
	TiDBImportingData = "tidb_import_data"

	// tidb_opt_agg_push_down is used to endable/disable the optimizer rule of aggregation push down.
	TiDBOptAggPushDown = "tidb_opt_agg_push_down"

	// tidb_opt_insubquery_unfold is used to enable/disable the optimizer rule of in subquery unfold.
	TiDBOptInSubqUnFolding = "tidb_opt_insubquery_unfold"

	// tidb_build_stats_concurrency is used to speed up the ANALYZE statement, when a table has multiple indices,
	// those indices can be scanned concurrently, with the cost of higher system performance impact.
	TiDBBuildStatsConcurrency = "tidb_build_stats_concurrency"

	// tidb_checksum_table_concurrency is used to speed up the ADMIN CHECKSUM TABLE
	// statement, when a table has multiple indices, those indices can be
	// scanned concurrently, with the cost of higher system performance impact.
	TiDBChecksumTableConcurrency = "tidb_checksum_table_concurrency"

	// TiDBCurrentTS is used to get the current transaction timestamp.
	// It is read-only.
	TiDBCurrentTS = "tidb_current_ts"

	// tidb_config is a read-only variable that shows the config of the current server.
	TiDBConfig = "tidb_config"

	// tidb_distsql_scan_concurrency is used to set the concurrency of a distsql scan task.
	// A distsql scan task can be a table scan or a index scan, which may be distributed to many TiKV nodes.
	// Higher concurrency may reduce latency, but with the cost of higher memory usage and system performance impact.
	// If the query has a LIMIT clause, high concurrency makes the system do much more work than needed.
	TiDBDistSQLScanConcurrency = "tidb_distsql_scan_concurrency"

	// tidb_index_join_batch_size is used to set the batch size of a index lookup join.
	// The index lookup join fetches batches of data from outer executor and constructs ranges for inner executor.
	// This value controls how much of data in a batch to do the index join.
	// Large value may reduce the latency but consumes more system resource.
	TiDBIndexJoinBatchSize = "tidb_index_join_batch_size"

	// tidb_index_lookup_size is used for index lookup executor.
	// The index lookup executor first scan a batch of handles from a index, then use those handles to lookup the table
	// rows, this value controls how much of handles in a batch to do a lookup task.
	// Small value sends more RPCs to TiKV, consume more system resource.
	// Large value may do more work than needed if the query has a limit.
	TiDBIndexLookupSize = "tidb_index_lookup_size"

	// tidb_index_lookup_concurrency is used for index lookup executor.
	// A lookup task may have 'tidb_index_lookup_size' of handles at maximun, the handles may be distributed
	// in many TiKV nodes, we executes multiple concurrent index lookup tasks concurrently to reduce the time
	// waiting for a task to finish.
	// Set this value higher may reduce the latency but consumes more system resource.
	TiDBIndexLookupConcurrency = "tidb_index_lookup_concurrency"

	// tidb_index_serial_scan_concurrency is used for controlling the concurrency of index scan operation
	// when we need to keep the data output order the same as the order of index data.
	TiDBIndexSerialScanConcurrency = "tidb_index_serial_scan_concurrency"

	// tidb_skip_utf8_check skips the UTF8 validate process, validate UTF8 has performance cost, if we can make sure
	// the input string values are valid, we can skip the check.
	TiDBSkipUTF8Check = "tidb_skip_utf8_check"

	// tidb_batch_insert is used to enable/disable auto-split insert data. If set this option on, insert executor will automatically
	// insert data into multiple batches and use a single txn for each batch. This will be helpful when inserting large data.
	TiDBBatchInsert = "tidb_batch_insert"

	// tidb_batch_delete is used to enable/disable auto-split delete data. If set this option on, delete executor will automatically
	// split data into multiple batches and use a single txn for each batch. This will be helpful when deleting large data.
	TiDBBatchDelete = "tidb_batch_delete"

	// tidb_dml_batch_size is used to split the insert/delete data into small batches.
	// It only takes effort when tidb_batch_insert/tidb_batch_delete is on.
	// Its default value is 20000. When the row size is large, 20k rows could be larger than 100MB.
	// User could change it to a smaller one to avoid breaking the transaction size limitation.
	TiDBDMLBatchSize = "tidb_dml_batch_size"

	// tidb_max_chunk_capacity is used to control the max chunk size during query execution.
	TiDBMaxChunkSize = "tidb_max_chunk_size"

	// The following session variables controls the memory quota during query execution.
	// "tidb_mem_quota_query":				control the memory quota of a query.
	// "tidb_mem_quota_hashjoin": 			control the memory quota of "HashJoinExec".
	// "tidb_mem_quota_sort":     			control the memory quota of "SortExec".
	// "tidb_mem_quota_topn":     			control the memory quota of "TopNExec".
	// "tidb_mem_quota_indexlookupreader":	control the memory quota of "IndexLookUpExecutor".
	TIDBMemQuotaQuery             = "tidb_mem_quota_query"             // Bytes.
	TIDBMemQuotaHashJoin          = "tidb_mem_quota_hashjoin"          // Bytes.
	TIDBMemQuotaSort              = "tidb_mem_quota_sort"              // Bytes.
	TIDBMemQuotaTopn              = "tidb_mem_quota_topn"              // Bytes.
	TIDBMemQuotaIndexLookupReader = "tidb_mem_quota_indexlookupreader" // Bytes.

	// tidb_general_log is used to log every query in the server in info level.
	TiDBGeneralLog = "tidb_general_log"

	// tidb_enable_streaming enables TiDB to use streaming API for coprocessor requests.
	TiDBEnableStreaming = "tidb_enable_streaming"
)

TiDB system variable names.

View Source 
const (
	DefIndexLookupConcurrency        = 4
	DefIndexSerialScanConcurrency    = 1
	DefIndexJoinBatchSize            = 25000
	DefIndexLookupSize               = 20000
	DefDistSQLScanConcurrency        = 15
	DefBuildStatsConcurrency         = 4
	DefChecksumTableConcurrency      = 4
	DefSkipUTF8Check                 = false
	DefOptAggPushDown                = false
	DefOptInSubqUnfolding            = false
	DefBatchInsert                   = false
	DefBatchDelete                   = false
	DefCurretTS                      = 0
	DefMaxChunkSize                  = 1024
	DefDMLBatchSize                  = 20000
	DefTiDBMemQuotaQuery             = 32 << 30 // 32GB.
	DefTiDBMemQuotaHashJoin          = 32 << 30 // 32GB.
	DefTiDBMemQuotaSort              = 32 << 30 // 32GB.
	DefTiDBMemQuotaTopn              = 32 << 30 // 32GB.
	DefTiDBMemQuotaIndexLookupReader = 32 << 30 // 32GB.
	DefTiDBGeneralLog                = 0
)

Default TiDB system variable values.

Variables

View Source 
var (
	ErrCantSetToNull  = terror.ClassVariable.New(codeCantSetToNull, "cannot set variable to null")
	ErrSnapshotTooOld = terror.ClassVariable.New(codeSnapshotTooOld, "snapshot is older than GC safe point %s")
)

Error instances.

View Source 
var (
	UnknownStatusVar   = terror.ClassVariable.New(CodeUnknownStatusVar, "unknown status variable")
	UnknownSystemVar   = terror.ClassVariable.New(CodeUnknownSystemVar, "unknown system variable '%s'")
	ErrIncorrectScope  = terror.ClassVariable.New(CodeIncorrectScope, "Incorrect variable scope")
	ErrUnknownTimeZone = terror.ClassVariable.New(CodeUnknownTimeZone, "unknown or incorrect time zone: %s")
	ErrReadOnly        = terror.ClassVariable.New(CodeReadOnly, "variable is read only")
)

Variable errors

View Source 
var DefaultStatusVarScopeFlag = ScopeGlobal | ScopeSession

DefaultStatusVarScopeFlag is the default scope of status variables.

View Source 
var (
	ProcessGeneralLog uint32
)

Process global variables.

View Source 
var SetNamesVariables = []string{
	"character_set_client",
	"character_set_connection",
	"character_set_results",
}

SetNamesVariables is the system variable names related to set names statements.

View Source 
var SynonymsSysVariables = map[string][]string{}

SynonymsSysVariables is synonyms of system variables.

View Source 
var SysVars map[string]*SysVar

SysVars is global sys vars map.

Functions

func GetGlobalSystemVar 

func GetGlobalSystemVar(s *SessionVars, key string) (string, error)

GetGlobalSystemVar gets a global system variable.

func GetScopeNoneSystemVar 

func GetScopeNoneSystemVar(key string) (string, bool, error)

GetScopeNoneSystemVar checks the validation of `key`, and return the default value if its scope is `ScopeNone`.

func GetSessionOnlySysVars 

func GetSessionOnlySysVars(s *SessionVars, key string) (string, bool, error)

GetSessionOnlySysVars get the default value defined in code for session only variable. The return bool value indicates whether it's a session only variable.

func GetSessionSystemVar 

func GetSessionSystemVar(s *SessionVars, key string) (string, error)

GetSessionSystemVar gets a system variable. If it is a session only variable, use the default value defined in code. Returns error if there is no such variable.

func GetStatusVars 

func GetStatusVars(vars *SessionVars) (map[string]*StatusVal, error)

GetStatusVars gets registered statistics status variables. TODO: Refactor this function to avoid repeated memory allocation / dealloc

func GoTimeToTS 

func GoTimeToTS(t time.Time) uint64

GoTimeToTS converts a Go time to uint64 timestamp.

func RegisterStatistics 

func RegisterStatistics(s Statistics)

RegisterStatistics registers statistics.

func SetSessionSystemVar 

func SetSessionSystemVar(vars *SessionVars, name string, value types.Datum) error

SetSessionSystemVar sets system variable and updates SessionVars states.

func TiDBOptOn 

func TiDBOptOn(opt string) bool

TiDBOptOn could be used for all tidb session variable options, we use "ON"/1 to turn on those options.

Types

type GlobalVarAccessor 

type GlobalVarAccessor interface {
	// GetAllSysVars gets all the global system variable values.
	GetAllSysVars() (map[string]string, error)
	// GetGlobalSysVar gets the global system variable value for name.
	GetGlobalSysVar(name string) (string, error)
	// SetGlobalSysVar sets the global system variable name to value.
	SetGlobalSysVar(name string, value string) error
}

GlobalVarAccessor is the interface for accessing global scope system and status variables.

type RetryInfo 

type RetryInfo struct {
	Retrying               bool
	DroppedPreparedStmtIDs []uint32
	// contains filtered or unexported fields
}

RetryInfo saves retry information.

func (*RetryInfo) AddAutoIncrementID 

func (r *RetryInfo) AddAutoIncrementID(id int64)

AddAutoIncrementID adds id to AutoIncrementIDs.

func (*RetryInfo) Clean 

func (r *RetryInfo) Clean()

Clean does some clean work.

func (*RetryInfo) GetCurrAutoIncrementID 

func (r *RetryInfo) GetCurrAutoIncrementID() (int64, error)

GetCurrAutoIncrementID gets current AutoIncrementID.

func (*RetryInfo) ResetOffset 

func (r *RetryInfo) ResetOffset()

ResetOffset resets the current retry offset.

type ScopeFlag 

type ScopeFlag uint8

ScopeFlag is for system variable whether can be changed in global/session dynamically or not. 

const (
	// ScopeNone means the system variable can not be changed dynamically.
	ScopeNone ScopeFlag = 0
	// ScopeGlobal means the system variable can be changed globally.
	ScopeGlobal ScopeFlag = 1 << 0
	// ScopeSession means the system variable can only be changed in current session.
	ScopeSession ScopeFlag = 1 << 1
)

type SessionVars 

type SessionVars struct {
	// UsersLock is a lock for user defined variables.
	UsersLock sync.RWMutex
	// Users are user defined variables.
	Users map[string]string

	// PreparedStmts stores prepared statement.
	PreparedStmts        map[uint32]interface{}
	PreparedStmtNameToID map[string]uint32

	// params for prepared statements
	PreparedParams []interface{}

	// retry information
	RetryInfo *RetryInfo
	// Should be reset on transaction finished.
	TxnCtx *TransactionContext

	Status           uint16
	PrevLastInsertID uint64 // PrevLastInsertID is the last insert ID of previous statement.
	LastInsertID     uint64 // LastInsertID is the auto-generated ID in the current statement.
	InsertID         uint64 // InsertID is the given insert ID of an auto_increment column.
	// PrevAffectedRows is the affected-rows value(DDL is 0, DML is the number of affected rows).
	PrevAffectedRows int64

	// ClientCapability is client's capability.
	ClientCapability uint32

	// TLSConnectionState is the TLS connection state (nil if not using TLS).
	TLSConnectionState *tls.ConnectionState

	// ConnectionID is the connection id of the current session.
	ConnectionID uint64

	// PlanID is the unique id of logical and physical plan.
	PlanID int

	// User is the user identity with which the session login.
	User *auth.UserIdentity

	// CurrentDB is the default database of this session.
	CurrentDB string

	// StrictSQLMode indicates if the session is in strict mode.
	StrictSQLMode bool

	// CommonGlobalLoaded indicates if common global variable has been loaded for this session.
	CommonGlobalLoaded bool

	// InRestrictedSQL indicates if the session is handling restricted SQL execution.
	InRestrictedSQL bool

	// SnapshotTS is used for reading history data. For simplicity, SnapshotTS only supports distsql request.
	SnapshotTS uint64

	// SnapshotInfoschema is used with SnapshotTS, when the schema version at snapshotTS less than current schema
	// version, we load an old version schema for query.
	SnapshotInfoschema interface{}

	// BinlogClient is used to write binlog.
	BinlogClient interface{}

	// GlobalVarsAccessor is used to set and get global variables.
	GlobalVarsAccessor GlobalVarAccessor

	// LastFoundRows is the number of found rows of last query statement
	LastFoundRows uint64

	// StmtCtx holds variables for current executing statement.
	StmtCtx *stmtctx.StatementContext

	// AllowAggPushDown can be set to false to forbid aggregation push down.
	AllowAggPushDown bool

	// AllowInSubqueryUnFolding can be set to true to fold in subquery
	AllowInSubqueryUnFolding bool

	// CurrInsertValues is used to record current ValuesExpr's values.
	// See http://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_values
	CurrInsertValues interface{}

	// Per-connection time zones. Each client that connects has its own time zone setting, given by the session time_zone variable.
	// See https://dev.mysql.com/doc/refman/5.7/en/time-zone-support.html
	TimeZone *time.Location

	SQLMode mysql.SQLMode

	// ImportingData is true when importing data.
	ImportingData bool

	// SkipUTF8Check check on input value.
	SkipUTF8Check bool

	// BuildStatsConcurrencyVar is used to control statistics building concurrency.
	BuildStatsConcurrencyVar int

	// IndexJoinBatchSize is the batch size of a index lookup join.
	IndexJoinBatchSize int

	// IndexLookupSize is the number of handles for an index lookup task in index double read executor.
	IndexLookupSize int

	// IndexLookupConcurrency is the number of concurrent index lookup worker.
	IndexLookupConcurrency int

	// DistSQLScanConcurrency is the number of concurrent dist SQL scan worker.
	DistSQLScanConcurrency int

	// IndexSerialScanConcurrency is the number of concurrent index serial scan worker.
	IndexSerialScanConcurrency int

	// BatchInsert indicates if we should split insert data into multiple batches.
	BatchInsert bool

	// BatchDelete indicates if we should split delete data into multiple batches.
	BatchDelete bool

	// DMLBatchSize indicates the size of batches for DML.
	// It will be used when BatchInsert or BatchDelete is on.
	DMLBatchSize int

	// MaxRowCountForINLJ defines max row count that the outer table of index nested loop join could be without force hint.
	MaxRowCountForINLJ int

	// IDAllocator is provided by kvEncoder, if it is provided, we will use it to alloc auto id instead of using
	// Table.alloc.
	IDAllocator autoid.Allocator

	// MaxChunkSize defines max row count of a Chunk during query execution.
	MaxChunkSize int

	// MemQuotaQuery defines the memory quota for a query.
	MemQuotaQuery int64
	// MemQuotaHashJoin defines the memory quota for a hash join executor.
	MemQuotaHashJoin int64
	// MemQuotaSort defines the memory quota for a sort executor.
	MemQuotaSort int64
	// MemQuotaTopn defines the memory quota for a top n executor.
	MemQuotaTopn int64
	// MemQuotaIndexLookupReader defines the memory quota for a index lookup reader executor.
	MemQuotaIndexLookupReader int64

	// EnableStreaming indicates whether the coprocessor request can use streaming API.
	// TODO: remove this after tidb-server configuration "enable-streaming' removed.
	EnableStreaming bool
	// contains filtered or unexported fields
}

SessionVars is to handle user-defined or global variables in the current session.

func NewSessionVars 

func NewSessionVars() *SessionVars

NewSessionVars creates a session vars object.

func (*SessionVars) CleanBuffers 

func (s *SessionVars) CleanBuffers()

CleanBuffers cleans the temporary bufs

func (*SessionVars) GetCharsetInfo 

func (s *SessionVars) GetCharsetInfo() (charset, collation string)

GetCharsetInfo gets charset and collation for current context. What character set should the server translate a statement to after receiving it? For this, the server uses the character_set_connection and collation_connection system variables. It converts statements sent by the client from character_set_client to character_set_connection (except for string literals that have an introducer such as _latin1 or _utf8). collation_connection is important for comparisons of literal strings. For comparisons of strings with column values, collation_connection does not matter because columns have their own collation, which has a higher collation precedence. See https://dev.mysql.com/doc/refman/5.7/en/charset-connection.html

func (*SessionVars) GetNextPreparedStmtID 

func (s *SessionVars) GetNextPreparedStmtID() uint32

GetNextPreparedStmtID generates and returns the next session scope prepared statement id.

func (*SessionVars) GetStatusFlag 

func (s *SessionVars) GetStatusFlag(flag uint16) bool

GetStatusFlag gets the session server status variable, returns true if it is on.

func (*SessionVars) GetSystemVar 

func (s *SessionVars) GetSystemVar(name string) (string, bool)

GetSystemVar gets the string value of a system variable.

func (*SessionVars) GetTimeZone 

func (s *SessionVars) GetTimeZone() *time.Location

GetTimeZone returns the value of time_zone session variable.

func (*SessionVars) GetWriteStmtBufs 

func (s *SessionVars) GetWriteStmtBufs() *WriteStmtBufs

GetWriteStmtBufs get pointer of SessionVars.writeStmtBufs.

func (*SessionVars) InTxn 

func (s *SessionVars) InTxn() bool

InTxn returns if the session is in transaction.

func (*SessionVars) IsAutocommit 

func (s *SessionVars) IsAutocommit() bool

IsAutocommit returns if the session is set to autocommit.

func (*SessionVars) ResetPrevAffectedRows 

func (s *SessionVars) ResetPrevAffectedRows()

ResetPrevAffectedRows reset the prev-affected-rows variable.

func (*SessionVars) SetLastInsertID 

func (s *SessionVars) SetLastInsertID(insertID uint64)

SetLastInsertID saves the last insert id to the session context. TODO: we may store the result for last_insert_id sys var later.

func (*SessionVars) SetStatusFlag 

func (s *SessionVars) SetStatusFlag(flag uint16, on bool)

SetStatusFlag sets the session server status variable. If on is ture sets the flag in session status, otherwise removes the flag.

func (*SessionVars) SetSystemVar 

func (s *SessionVars) SetSystemVar(name string, val string) error

SetSystemVar sets the value of a system variable.

type Statistics 

type Statistics interface {
	// GetScope gets the status variables scope.
	GetScope(status string) ScopeFlag
	// Stats returns the statistics status variables.
	Stats(*SessionVars) (map[string]interface{}, error)
}

Statistics is the interface of statistics.

type StatusVal 

type StatusVal struct {
	Scope ScopeFlag
	Value interface{}
}

StatusVal is the value of the corresponding status variable.

type SysVar 

type SysVar struct {
	// Scope is for whether can be changed or not
	Scope ScopeFlag

	// Name is the variable name.
	Name string

	// Value is the variable value.
	Value string
}

SysVar is for system variable.

func GetSysVar 

func GetSysVar(name string) *SysVar

GetSysVar returns sys var info for name as key.

type TableDelta 

type TableDelta struct {
	Delta int64
	Count int64
}

TableDelta stands for the changed count for one table.

type TransactionContext 

type TransactionContext struct {
	ForUpdate     bool
	DirtyDB       interface{}
	Binlog        interface{}
	InfoSchema    interface{}
	Histroy       interface{}
	SchemaVersion int64
	StartTS       uint64
	Shard         *int64
	TableDeltaMap map[int64]TableDelta

	// For metrics.
	CreateTime     time.Time
	StatementCount int
}

TransactionContext is used to store variables that has transaction scope.

func (*TransactionContext) ClearDelta added in v1.0.5 

func (tc *TransactionContext) ClearDelta()

ClearDelta clears the delta map.

func (*TransactionContext) UpdateDeltaForTable 

func (tc *TransactionContext) UpdateDeltaForTable(tableID int64, delta int64, count int64)

UpdateDeltaForTable updates the delta info for some table.

type WriteStmtBufs 

type WriteStmtBufs struct {
	// RowValBuf is used by tablecodec.EncodeRow, to reduce runtime.growslice.
	RowValBuf []byte
	// BufStore stores temp KVs for a row when executing insert statement.
	// We could reuse a BufStore for multiple rows of a session to reduce memory allocations.
	BufStore *kv.BufferStore
	// AddRowValues use to store temp insert rows value, to reduce memory allocations when importing data.
	AddRowValues []types.Datum

	// IndexValsBuf is used by index.FetchValues
	IndexValsBuf []types.Datum
	// IndexKeyBuf is used by index.GenIndexKey
	IndexKeyBuf []byte
}

WriteStmtBufs can be used by insert/replace/delete/update statement. TODO: use a common memory pool to replace this.

Source Files

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