variable

package
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 Go to latest Published: Nov 21, 2019 License: GPL-3.0 Imports: 25 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"
	TxnIsolationOneShot = "tx_isolation_one_shot"
)

special session variables.

View Source 
const (
	CodeUnknownStatusVar    terror.ErrCode = 1
	CodeUnknownSystemVar    terror.ErrCode = mysql.ErrUnknownSystemVariable
	CodeIncorrectScope      terror.ErrCode = mysql.ErrIncorrectGlobalLocalVar
	CodeUnknownTimeZone     terror.ErrCode = mysql.ErrUnknownTimeZone
	CodeReadOnly            terror.ErrCode = mysql.ErrVariableIsReadonly
	CodeWrongValueForVar    terror.ErrCode = mysql.ErrWrongValueForVar
	CodeWrongTypeForVar     terror.ErrCode = mysql.ErrWrongTypeForVar
	CodeTruncatedWrongValue terror.ErrCode = mysql.ErrTruncatedWrongValue
)

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"
	// GeneralLog is the name for 'general_log' system variable.
	GeneralLog = "general_log"
	// AvoidTemporalUpgrade is the name for 'avoid_temporal_upgrade' system variable.
	AvoidTemporalUpgrade = "avoid_temporal_upgrade"
	// BigTables is the name for 'big_tables' system variable.
	BigTables = "big_tables"
	// CheckProxyUsers is the name for 'check_proxy_users' system variable.
	CheckProxyUsers = "check_proxy_users"
	// CoreFile is the name for 'core_file' system variable.
	CoreFile = "core_file"
	// DefaultWeekFormat is the name for 'default_week_format' system variable.
	DefaultWeekFormat = "default_week_format"
	// GroupConcatMaxLen is the name for 'group_concat_max_len' system variable.
	GroupConcatMaxLen = "group_concat_max_len"
	// DelayKeyWrite is the name for 'delay_key_write' system variable.
	DelayKeyWrite = "delay_key_write"
	// EndMakersInJSON is the name for 'end_markers_in_json' system variable.
	EndMakersInJSON = "end_markers_in_json"
	// InnodbCommitConcurrency is the name for 'innodb_commit_concurrency' system variable.
	InnodbCommitConcurrency = "innodb_commit_concurrency"
	// InnodbFastShutdown is the name for 'innodb_fast_shutdown' system variable.
	InnodbFastShutdown = "innodb_fast_shutdown"
	// InnodbLockWaitTimeout is the name for 'innodb_lock_wait_timeout' system variable.
	InnodbLockWaitTimeout = "innodb_lock_wait_timeout"
	// SQLLogBin is the name for 'sql_log_bin' system variable.
	SQLLogBin = "sql_log_bin"
	// MaxSortLength is the name for 'max_sort_length' system variable.
	MaxSortLength = "max_sort_length"
	// MaxSpRecursionDepth is the name for 'max_sp_recursion_depth' system variable.
	MaxSpRecursionDepth = "max_sp_recursion_depth"
	// MaxUserConnections is the name for 'max_user_connections' system variable.
	MaxUserConnections = "max_user_connections"
	// OfflineMode is the name for 'offline_mode' system variable.
	OfflineMode = "offline_mode"
	// InteractiveTimeout is the name for 'interactive_timeout' system variable.
	InteractiveTimeout = "interactive_timeout"
	// FlushTime is the name for 'flush_time' system variable.
	FlushTime = "flush_time"
	// PseudoSlaveMode is the name for 'pseudo_slave_mode' system variable.
	PseudoSlaveMode = "pseudo_slave_mode"
	// LowPriorityUpdates is the name for 'low_priority_updates' system variable.
	LowPriorityUpdates = "low_priority_updates"
	// SessionTrackGtids is the name for 'session_track_gtids' system variable.
	SessionTrackGtids = "session_track_gtids"
	// OldPasswords is the name for 'old_passwords' system variable.
	OldPasswords = "old_passwords"
	// MaxConnections is the name for 'max_connections' system variable.
	MaxConnections = "max_connections"
	// SkipNameResolve is the name for 'skip_name_resolve' system variable.
	SkipNameResolve = "skip_name_resolve"
	// ForeignKeyChecks is the name for 'foreign_key_checks' system variable.
	ForeignKeyChecks = "foreign_key_checks"
	// SQLSafeUpdates is the name for 'sql_safe_updates' system variable.
	SQLSafeUpdates = "sql_safe_updates"
	// WarningCount is the name for 'warning_count' system variable.
	WarningCount = "warning_count"
	// ErrorCount is the name for 'error_count' system variable.
	ErrorCount = "error_count"
	// SQLSelectLimit is the name for 'sql_select_limit' system variable.
	SQLSelectLimit = "sql_select_limit"
	// MaxConnectErrors is the name for 'max_connect_errors' system variable.
	MaxConnectErrors = "max_connect_errors"
	// TableDefinitionCache is the name for 'table_definition_cache' system variable.
	TableDefinitionCache = "table_definition_cache"
	// TmpTableSize is the name for 'tmp_table_size' system variable.
	TmpTableSize = "tmp_table_size"
	// ConnectTimeout is the name for 'connect_timeout' system variable.
	ConnectTimeout = "connect_timeout"
	// SyncBinlog is the name for 'sync_binlog' system variable.
	SyncBinlog = "sync_binlog"
	// BlockEncryptionMode is the name for 'block_encryption_mode' system variable.
	BlockEncryptionMode = "block_encryption_mode"
)
View Source 
const (
	// tidb_snapshot is used for reading history data, the default value is empty string.
	// The value can be a datetime string like '2017-11-11 20:20:20' or a tso string. When this variable is set, the session reads history data of that time.
	TiDBSnapshot = "tidb_snapshot"

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

	// Auto analyze will run if (table modify count)/(table row count) is greater than this value.
	TiDBAutoAnalyzeRatio = "tidb_auto_analyze_ratio"

	// Auto analyze will run if current time is within start time and end time.
	TiDBAutoAnalyzeStartTime = "tidb_auto_analyze_start_time"
	TiDBAutoAnalyzeEndTime   = "tidb_auto_analyze_end_time"

	// 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_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"

	// 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_mergejoin": 			control the memory quota of "MergeJoinExec".
	// "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".
	// "tidb_mem_quota_indexlookupjoin":	control the memory quota of "IndexLookUpJoin".
	// "tidb_mem_quota_nestedloopapply": 	control the memory quota of "NestedLoopApplyExec".
	TIDBMemQuotaQuery             = "tidb_mem_quota_query"             // Bytes.
	TIDBMemQuotaHashJoin          = "tidb_mem_quota_hashjoin"          // Bytes.
	TIDBMemQuotaMergeJoin         = "tidb_mem_quota_mergejoin"         // Bytes.
	TIDBMemQuotaSort              = "tidb_mem_quota_sort"              // Bytes.
	TIDBMemQuotaTopn              = "tidb_mem_quota_topn"              // Bytes.
	TIDBMemQuotaIndexLookupReader = "tidb_mem_quota_indexlookupreader" // Bytes.
	TIDBMemQuotaIndexLookupJoin   = "tidb_mem_quota_indexlookupjoin"   // Bytes.
	TIDBMemQuotaNestedLoopApply   = "tidb_mem_quota_nestedloopapply"   // Bytes.

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

	// tidb_retry_limit is the maximun number of retries when committing a transaction.
	TiDBRetryLimit = "tidb_retry_limit"

	// tidb_disable_txn_auto_retry disables transaction auto retry.
	TiDBDisableTxnAutoRetry = "tidb_disable_txn_auto_retry"

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

	// tidb_optimizer_selectivity_level is used to control the selectivity estimation level.
	TiDBOptimizerSelectivityLevel = "tidb_optimizer_selectivity_level"

	// tidb_enable_table_partition is used to enable table partition feature.
	TiDBEnableTablePartition = "tidb_enable_table_partition"
)

TiDB system variable names that only in session scope.

View Source 
const (
	// 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_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_opt_insubquery_unfold is used to enable/disable the optimizer rule of in subquery unfold.
	TiDBOptInSubqUnFolding = "tidb_opt_insubquery_unfold"

	// 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_lookup_join_concurrency is used for index lookup join executor.
	// IndexLookUpJoin starts "tidb_index_lookup_join_concurrency" inner workers
	// to fetch inner rows and join the matched (outer, inner) row pairs.
	TiDBIndexLookupJoinConcurrency = "tidb_index_lookup_join_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_max_chunk_capacity is used to control the max chunk size during query execution.
	TiDBMaxChunkSize = "tidb_max_chunk_size"

	// tidb_enable_cascades_planner is used to control whether to enable the cascades planner.
	TiDBEnableCascadesPlanner = "tidb_enable_cascades_planner"

	// 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_hash_join_concurrency is used for hash join executor.
	// The hash join outer executor starts multiple concurrent join workers to probe the hash table.
	TiDBHashJoinConcurrency = "tidb_hash_join_concurrency"

	// tidb_projection_concurrency is used for projection operator.
	// This variable controls the worker number of projection operator.
	TiDBProjectionConcurrency = "tidb_projection_concurrency"

	// tidb_hashagg_partial_concurrency is used for hash agg executor.
	// The hash agg executor starts multiple concurrent partial workers to do partial aggregate works.
	TiDBHashAggPartialConcurrency = "tidb_hashagg_partial_concurrency"

	// tidb_hashagg_final_concurrency is used for hash agg executor.
	// The hash agg executor starts multiple concurrent final workers to do final aggregate works.
	TiDBHashAggFinalConcurrency = "tidb_hashagg_final_concurrency"

	// tidb_backoff_lock_fast is used for tikv backoff base time in milliseconds.
	TiDBBackoffLockFast = "tidb_backoff_lock_fast"

	// tidb_ddl_reorg_worker_cnt defines the count of ddl reorg workers.
	TiDBDDLReorgWorkerCount = "tidb_ddl_reorg_worker_cnt"

	// tidb_ddl_reorg_priority defines the operations priority of adding indices.
	// It can be: PRIORITY_LOW, PRIORITY_NORMAL, PRIORITY_HIGH
	TiDBDDLReorgPriority = "tidb_ddl_reorg_priority"

	// tidb_force_priority defines the operations priority of all statements.
	// It can be "NO_PRIORITY", "LOW_PRIORITY", "HIGH_PRIORITY", "DELAYED"
	TiDBForcePriority = "tidb_force_priority"

	// tidb_enable_radix_join indicates to use radix hash join algorithm to execute
	// HashJoin.
	TiDBEnableRadixJoin = "tidb_enable_radix_join"

	// tidb_constraint_check_in_place indicates to check the constraint when the SQL executing.
	// It could hurt the performance of bulking insert when it is ON.
	TiDBConstraintCheckInPlace = "tidb_constraint_check_in_place"
)

TiDB system variable names that both in session and global scope.

View Source 
const (
	DefIndexLookupConcurrency        = 4
	DefIndexLookupJoinConcurrency    = 4
	DefIndexSerialScanConcurrency    = 1
	DefIndexJoinBatchSize            = 25000
	DefIndexLookupSize               = 20000
	DefDistSQLScanConcurrency        = 15
	DefBuildStatsConcurrency         = 4
	DefAutoAnalyzeRatio              = 0.5
	DefAutoAnalyzeStartTime          = "00:00 +0000"
	DefAutoAnalyzeEndTime            = "23:59 +0000"
	DefChecksumTableConcurrency      = 4
	DefSkipUTF8Check                 = false
	DefOptAggPushDown                = false
	DefOptInSubqUnfolding            = false
	DefBatchInsert                   = false
	DefBatchDelete                   = false
	DefCurretTS                      = 0
	DefMaxChunkSize                  = 32
	DefDMLBatchSize                  = 20000
	DefTiDBMemQuotaHashJoin          = 32 << 30 // 32GB.
	DefTiDBMemQuotaMergeJoin         = 32 << 30 // 32GB.
	DefTiDBMemQuotaSort              = 32 << 30 // 32GB.
	DefTiDBMemQuotaTopn              = 32 << 30 // 32GB.
	DefTiDBMemQuotaIndexLookupReader = 32 << 30 // 32GB.
	DefTiDBMemQuotaIndexLookupJoin   = 32 << 30 // 32GB.
	DefTiDBMemQuotaNestedLoopApply   = 32 << 30 // 32GB.
	DefTiDBGeneralLog                = 0
	DefTiDBRetryLimit                = 10
	DefTiDBDisableTxnAutoRetry       = false
	DefTiDBConstraintCheckInPlace    = false
	DefTiDBHashJoinConcurrency       = 5
	DefTiDBProjectionConcurrency     = 4
	DefTiDBOptimizerSelectivityLevel = 0
	DefTiDBDDLReorgWorkerCount       = 16
	DefTiDBHashAggPartialConcurrency = 4
	DefTiDBHashAggFinalConcurrency   = 4
	DefTiDBForcePriority             = mysql.NoPriority
	DefTiDBUseRadixJoin              = false
)

Default TiDB system variable values.

View Source 
const (

	// AnalyzeFullTimeFormat is the full format of analyze start time and end time.
	AnalyzeFullTimeFormat = "15:04 -0700"
)

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, mysql.MySQLErrName[mysql.ErrUnknownSystemVariable])
	ErrIncorrectScope      = terror.ClassVariable.New(CodeIncorrectScope, mysql.MySQLErrName[mysql.ErrIncorrectGlobalLocalVar])
	ErrUnknownTimeZone     = terror.ClassVariable.New(CodeUnknownTimeZone, mysql.MySQLErrName[mysql.ErrUnknownTimeZone])
	ErrReadOnly            = terror.ClassVariable.New(CodeReadOnly, "variable is read only")
	ErrWrongValueForVar    = terror.ClassVariable.New(CodeWrongValueForVar, mysql.MySQLErrName[mysql.ErrWrongValueForVar])
	ErrWrongTypeForVar     = terror.ClassVariable.New(CodeWrongTypeForVar, mysql.MySQLErrName[mysql.ErrWrongTypeForVar])
	ErrTruncatedWrongValue = terror.ClassVariable.New(CodeTruncatedWrongValue, mysql.MySQLErrName[mysql.ErrTruncatedWrongValue])
)

Variable errors

View Source 
var (
	ProcessGeneralLog uint32

	DDLSlowOprThreshold uint32 = 300 // DDLSlowOprThreshold is the threshold for ddl slow operations, uint is millisecond.
	ForcePriority              = int32(DefTiDBForcePriority)
	ServerHostname, _          = os.Hostname()
)

Process global variables.

View Source 
var DefaultStatusVarScopeFlag = ScopeGlobal | ScopeSession

DefaultStatusVarScopeFlag is the default scope of status 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 GetDDLReorgWorkerCounter 

func GetDDLReorgWorkerCounter() int32

GetDDLReorgWorkerCounter gets ddlReorgWorkerCounter.

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 SetDDLReorgWorkerCounter 

func SetDDLReorgWorkerCounter(cnt int32)

SetDDLReorgWorkerCounter sets ddlReorgWorkerCounter count. Max worker count is maxDDLReorgWorkerCount.

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.

func ValidateGetSystemVar 

func ValidateGetSystemVar(name string, isGlobal bool) error

ValidateGetSystemVar checks if system variable exists and validates its scope when get system variable.

func ValidateSetSystemVar 

func ValidateSetSystemVar(vars *SessionVars, name string, value string) (string, error)

ValidateSetSystemVar checks if system variable satisfies specific restriction.

Types

type BatchSize 

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

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

BatchSize defines batch size values.

type Concurrency 

type Concurrency struct {
	// IndexLookupConcurrency is the number of concurrent index lookup worker.
	IndexLookupConcurrency int

	// IndexLookupJoinConcurrency is the number of concurrent index lookup join inner worker.
	IndexLookupJoinConcurrency int

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

	// HashJoinConcurrency is the number of concurrent hash join outer worker.
	HashJoinConcurrency int

	// ProjectionConcurrency is the number of concurrent projection worker.
	ProjectionConcurrency int64

	// HashAggPartialConcurrency is the number of concurrent hash aggregation partial worker.
	HashAggPartialConcurrency int

	// HashAggPartialConcurrency is the number of concurrent hash aggregation final worker.
	HashAggFinalConcurrency int

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

Concurrency defines concurrency values.

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 MemQuota 

type MemQuota struct {
	// MemQuotaQuery defines the memory quota for a query.
	MemQuotaQuery int64
	// MemQuotaHashJoin defines the memory quota for a hash join executor.
	MemQuotaHashJoin int64
	// MemQuotaMergeJoin defines the memory quota for a merge join executor.
	MemQuotaMergeJoin 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
	// MemQuotaIndexLookupJoin defines the memory quota for a index lookup join executor.
	MemQuotaIndexLookupJoin int64
	// MemQuotaNestedLoopApply defines the memory quota for a nested loop apply executor.
	MemQuotaNestedLoopApply int64
}

MemQuota defines memory quota values.

type MockGlobalAccessor 

type MockGlobalAccessor struct {
}

MockGlobalAccessor implements GlobalVarAccessor interface. it's used in tests

func NewMockGlobalAccessor 

func NewMockGlobalAccessor() *MockGlobalAccessor

NewMockGlobalAccessor implements GlobalVarAccessor interface.

func (*MockGlobalAccessor) GetAllSysVars 

func (m *MockGlobalAccessor) GetAllSysVars() (map[string]string, error)

GetAllSysVars implements GlobalVarAccessor.GetAllSysVars interface.

func (*MockGlobalAccessor) GetGlobalSysVar 

func (m *MockGlobalAccessor) GetGlobalSysVar(name string) (string, error)

GetGlobalSysVar implements GlobalVarAccessor.GetGlobalSysVar interface.

func (*MockGlobalAccessor) SetGlobalSysVar 

func (m *MockGlobalAccessor) SetGlobalSysVar(name string, value string) error

SetGlobalSysVar implements GlobalVarAccessor.SetGlobalSysVar interface.

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 {
	Concurrency
	MemQuota
	BatchSize
	RetryLimit          int64
	DisableTxnAutoRetry bool
	// 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]*ast.Prepared
	PreparedStmtNameToID map[string]uint32

	// params for prepared statements
	PreparedParams []types.Datum

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

	// KVVars is the variables for KV storage.
	KVVars *kv.Variables

	// TxnIsolationLevelOneShot is used to implements "set transaction isolation level ..."
	TxnIsolationLevelOneShot struct {
		// state 0 means default
		// state 1 means it's set in current transaction.
		// state 2 means it should be used in current transaction.
		State int
		Value string
	}

	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

	// PlanColumnID is the unique id for column when building plan.
	PlanColumnID int64

	// 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 chunk.Row

	// 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

	// LightningMode is true when the lightning use the kvencoder to transfer sql to raw kv.
	LightningMode bool

	// SkipUTF8Check check on input value.
	SkipUTF8Check bool

	// 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

	// 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

	// OptimizerSelectivityLevel defines the level of the selectivity estimation in plan.
	OptimizerSelectivityLevel int

	// EnableTablePartition enables table partition feature.
	EnableTablePartition bool

	// EnableCascadesPlanner enables the cascades planner.
	EnableCascadesPlanner bool

	// DDLReorgPriority is the operation priority of adding indices.
	DDLReorgPriority int

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

	// L2CacheSize indicates the size of CPU L2 cache, using byte as unit.
	L2CacheSize int

	// EnableRadixJoin indicates whether to use radix hash join to execute
	// HashJoin.
	EnableRadixJoin bool

	// ConstraintCheckInPlace indicates whether to check the constraint when the SQL executing.
	ConstraintCheckInPlace bool

	// CommandValue indicates which command current session is doing.
	CommandValue uint32
	// 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) AllocPlanColumnID 

func (s *SessionVars) AllocPlanColumnID() int64

AllocPlanColumnID allocates column id for plan.

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) GetExecuteArgumentsInfo 

func (s *SessionVars) GetExecuteArgumentsInfo() string

GetExecuteArgumentsInfo gets the argument list as a string of execute statement.

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) 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) Location 

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

Location returns the value of time_zone session variable. If it is nil, then return time.Local.

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
	ColSize  map[int64]int64
	InitTime time.Time // InitTime is the time that this delta is generated.
}

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 

func (tc *TransactionContext) ClearDelta()

ClearDelta clears the delta map.

func (*TransactionContext) UpdateDeltaForTable 

func (tc *TransactionContext) UpdateDeltaForTable(tableID int64, delta int64, count int64, colSize map[int64]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.

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