types

Documentation

Index

• type ColStatsTimeInfo
• type DDL
• type GlobalStatsInfo
• type IndexUsage
• type NeededItemTask
• type PartitionStatisticLoadTask
• type PersistFunc
• type StatsAnalyze
• type StatsCache
• type StatsGC
• type StatsGlobal
• type StatsHandle
• type StatsHistory
• type StatsLoad
• type StatsLock
• type StatsLockTable
• type StatsReadWriter
• type StatsSyncLoad
• type StatsUsage

Types

type ColStatsTimeInfo

type ColStatsTimeInfo struct {
	LastUsedAt     *types.Time // last time the column is used
	LastAnalyzedAt *types.Time // last time the column is analyzed
}

ColStatsTimeInfo records usage information of this column stats.

type DDL

type DDL interface {
	// HandleDDLEvent handles ddl events.
	HandleDDLEvent(changeEvent *notifier.SchemaChangeEvent) error
	// DDLEventCh returns ddl events channel in handle.
	DDLEventCh() chan *notifier.SchemaChangeEvent
}

DDL is used to handle ddl events.

type GlobalStatsInfo

type GlobalStatsInfo struct {
	HistIDs []int64
	// When the `isIndex == 0`, HistIDs will be the column IDs.
	// Otherwise, HistIDs will only contain the index ID.
	IsIndex      int
	StatsVersion int
}

GlobalStatsInfo represents the contextual information pertaining to global statistics.

type IndexUsage

type IndexUsage interface {
	// NewSessionIndexUsageCollector creates a new Collector for a session.
	NewSessionIndexUsageCollector() *indexusage.SessionIndexUsageCollector

	// GCIndexUsage removes unnecessary index usage data.
	GCIndexUsage() error

	// StartWorker starts for the collector worker.
	StartWorker()

	// Close closes and waits for the index usage collector worker.
	Close()

	// GetIndexUsage returns the index usage information
	GetIndexUsage(tableID int64, indexID int64) indexusage.Sample
}

IndexUsage is an interface to define the function of collecting index usage stats.

type NeededItemTask

type NeededItemTask struct {
	ToTimeout time.Time
	ResultCh  chan stmtctx.StatsLoadResult
	Item      model.StatsLoadItem
	Retry     int
}

NeededItemTask represents one needed column/indices with expire time.

type PartitionStatisticLoadTask

type PartitionStatisticLoadTask struct {
	JSONTable  *statsutil.JSONTable
	PhysicalID int64
}

PartitionStatisticLoadTask currently records a partition-level jsontable.

type PersistFunc

type PersistFunc func(ctx context.Context, jsonTable *statsutil.JSONTable, physicalID int64) error

PersistFunc is used to persist JSONTable in the partition level.

type StatsAnalyze

type StatsAnalyze interface {
	owner.Listener

	// InsertAnalyzeJob inserts analyze job into mysql.analyze_jobs and gets job ID for further updating job.
	InsertAnalyzeJob(job *statistics.AnalyzeJob, instance string, procID uint64) error

	// StartAnalyzeJob updates the job status to `running` and sets the start time.
	// There is no guarantee that the job record will actually be updated. If the job fails to start, an error will be logged.
	// It is OK because this won't affect the analysis job's success.
	StartAnalyzeJob(job *statistics.AnalyzeJob)

	// UpdateAnalyzeJobProgress updates the current progress of the analyze job.
	// There is no guarantee that the job record will actually be updated. If the job fails to update, an error will be logged.
	// It is OK because this won't affect the analysis job's success.
	UpdateAnalyzeJobProgress(job *statistics.AnalyzeJob, rowCount int64)

	// FinishAnalyzeJob updates the job status to `finished`, sets the end time, and updates the job info.
	// There is no guarantee that the job record will actually be updated. If the job fails to finish, an error will be logged.
	// It is OK because this won't affect the analysis job's success.
	FinishAnalyzeJob(job *statistics.AnalyzeJob, failReason error, analyzeType statistics.JobType)

	// DeleteAnalyzeJobs deletes the analyze jobs whose update time is earlier than updateTime.
	DeleteAnalyzeJobs(updateTime time.Time) error

	// CleanupCorruptedAnalyzeJobsOnCurrentInstance cleans up the corrupted analyze job.
	// A corrupted analyze job is one that is in a 'pending' or 'running' state,
	// but is associated with a TiDB instance that is either not currently running or has been restarted.
	// We use current running analyze jobs to check whether the analyze job is corrupted.
	CleanupCorruptedAnalyzeJobsOnCurrentInstance(currentRunningProcessIDs map[uint64]struct{}) error

	// CleanupCorruptedAnalyzeJobsOnDeadInstances purges analyze jobs that are associated with non-existent instances.
	// This function is specifically designed to handle jobs that have become corrupted due to
	// their associated instances being removed from the current cluster.
	CleanupCorruptedAnalyzeJobsOnDeadInstances() error

	// HandleAutoAnalyze analyzes the outdated tables. (The change percent of the table exceeds the threshold)
	// It also analyzes newly created tables and newly added indexes.
	HandleAutoAnalyze() (analyzed bool)

	// CheckAnalyzeVersion checks whether all the statistics versions of this table's columns and indexes are the same.
	CheckAnalyzeVersion(tblInfo *model.TableInfo, physicalIDs []int64, version *int) bool

	// Close closes the analyze worker.
	Close()
}

StatsAnalyze is used to handle auto-analyze and manage analyze jobs.

type StatsCache

type StatsCache interface {
	// Close closes this cache.
	Close()

	// Clear clears this cache.
	Clear()

	// Update reads stats meta from store and updates the stats map.
	Update(ctx context.Context, is infoschema.InfoSchema) error

	// MemConsumed returns its memory usage.
	MemConsumed() (size int64)

	// Get returns the specified table's stats.
	Get(tableID int64) (*statistics.Table, bool)

	// Put puts this table stats into the cache.
	Put(tableID int64, t *statistics.Table)

	// UpdateStatsCache updates the cache.
	UpdateStatsCache(addedTables []*statistics.Table, deletedTableIDs []int64)

	// GetNextCheckVersionWithOffset returns the last version with offset.
	// It is used to fetch updated statistics from the stats meta table.
	GetNextCheckVersionWithOffset() uint64

	// MaxTableStatsVersion returns the version of the current cache, which is defined as
	// the max table stats version the cache has in its lifecycle.
	MaxTableStatsVersion() uint64

	// Values returns all values in this cache.
	Values() []*statistics.Table

	// Len returns the length of this cache.
	Len() int

	// SetStatsCacheCapacity sets the cache's capacity.
	SetStatsCacheCapacity(capBytes int64)

	// Replace replaces this cache.
	Replace(cache StatsCache)

	// UpdateStatsHealthyMetrics updates stats healthy distribution metrics according to stats cache.
	UpdateStatsHealthyMetrics()
}

StatsCache is used to manage all table statistics in memory.

type StatsGC

type StatsGC interface {
	// GCStats will garbage collect the useless stats' info.
	// For dropped tables, we will first update their version
	// so that other tidb could know that table is deleted.
	GCStats(is infoschema.InfoSchema, ddlLease time.Duration) (err error)

	// ClearOutdatedHistoryStats clear outdated historical stats.
	// Only for test.
	ClearOutdatedHistoryStats() error

	// DeleteTableStatsFromKV deletes table statistics from kv.
	// A statsID refers to statistic of a table or a partition.
	DeleteTableStatsFromKV(statsIDs []int64) (err error)
}

StatsGC is used to GC unnecessary stats.

type StatsGlobal

type StatsGlobal interface {
	// MergePartitionStats2GlobalStatsByTableID merges partition stats to global stats by table ID.
	MergePartitionStats2GlobalStatsByTableID(sc sessionctx.Context,
		opts map[ast.AnalyzeOptionType]uint64, is infoschema.InfoSchema,
		info *GlobalStatsInfo,
		physicalID int64,
	) (err error)
}

StatsGlobal is used to manage partition table global stats.

type StatsHandle

type StatsHandle interface {
	// Pool is used to get a session or a goroutine to execute stats updating.
	statsutil.Pool

	// AutoAnalyzeProcIDGenerator is used to generate auto analyze proc ID.
	statsutil.AutoAnalyzeProcIDGenerator

	// LeaseGetter is used to get stats lease.
	statsutil.LeaseGetter

	// TableInfoGetter is used to get table meta info.
	statsutil.TableInfoGetter

	// GetTableStats retrieves the statistics table from cache, and the cache will be updated by a goroutine.
	GetTableStats(tblInfo *model.TableInfo) *statistics.Table

	// GetTableStatsForAutoAnalyze retrieves the statistics table from cache, but it will not return pseudo.
	GetTableStatsForAutoAnalyze(tblInfo *model.TableInfo) *statistics.Table

	// GetPartitionStats retrieves the partition stats from cache.
	GetPartitionStats(tblInfo *model.TableInfo, pid int64) *statistics.Table

	// GetPartitionStatsForAutoAnalyze retrieves the partition stats from cache, but it will not return pseudo.
	GetPartitionStatsForAutoAnalyze(tblInfo *model.TableInfo, pid int64) *statistics.Table

	// StatsGC is used to do the GC job.
	StatsGC

	// StatsUsage is used to handle table delta and stats usage.
	StatsUsage

	// StatsHistory is used to manage historical stats.
	StatsHistory

	// StatsAnalyze is used to handle auto-analyze and manage analyze jobs.
	StatsAnalyze

	// StatsCache is used to manage all table statistics in memory.
	StatsCache

	// StatsLock is used to manage locked stats.
	StatsLock

	// StatsReadWriter is used to read and write stats to the storage.
	StatsReadWriter

	// StatsGlobal is used to manage partition table global stats.
	StatsGlobal

	// DDL is used to handle ddl events.
	DDL
}

StatsHandle is used to manage TiDB Statistics.

type StatsHistory

type StatsHistory interface {
	// RecordHistoricalStatsMeta records stats meta of the specified version to stats_meta_history.
	RecordHistoricalStatsMeta(tableID int64, version uint64, source string, enforce bool)

	// CheckHistoricalStatsEnable check whether historical stats is enabled.
	CheckHistoricalStatsEnable() (enable bool, err error)

	// RecordHistoricalStatsToStorage records the given table's stats data to mysql.stats_history
	RecordHistoricalStatsToStorage(dbName string, tableInfo *model.TableInfo, physicalID int64, isPartition bool) (uint64, error)
}

StatsHistory is used to manage historical stats.

type StatsLoad

type StatsLoad struct {
	NeededItemsCh  chan *NeededItemTask
	TimeoutItemsCh chan *NeededItemTask
	sync.Mutex
}

StatsLoad is used to load stats concurrently TODO(hawkingrei): Our implementation of loading statistics is flawed. Currently, we enqueue tasks that require loading statistics into a channel, from which workers retrieve tasks to process. Then, using the singleflight mechanism, we filter out duplicate tasks. However, the issue with this approach is that it does not filter out all duplicate tasks, but only the duplicates within the number of workers. Such an implementation is not reasonable.

We should first filter all tasks through singleflight as shown in the diagram, and then use workers to load stats.

┌─────────▼──────────▼─────────────▼──────────────▼────────────────▼────────────────────┐ │ │ │ singleflight │ │ │ └───────────────────────────────────────────────────────────────────────────────────────┘

	            │                │
   ┌────────────▼──────┐ ┌───────▼───────────┐
   │                   │ │                   │
   │  syncload worker  │ │  syncload worker  │
   │                   │ │                   │
   └───────────────────┘ └───────────────────┘

type StatsLock

type StatsLock interface {
	// LockTables add locked tables id to store.
	// - tables: tables that will be locked.
	// Return the message of skipped tables and error.
	LockTables(tables map[int64]*StatsLockTable) (skipped string, err error)

	// LockPartitions add locked partitions id to store.
	// If the whole table is locked, then skip all partitions of the table.
	// - tid: table id of which will be locked.
	// - tableName: table name of which will be locked.
	// - pidNames: partition ids of which will be locked.
	// Return the message of skipped tables and error.
	// Note: If the whole table is locked, then skip all partitions of the table.
	LockPartitions(
		tid int64,
		tableName string,
		pidNames map[int64]string,
	) (skipped string, err error)

	// RemoveLockedTables remove tables from table locked records.
	// - tables: tables of which will be unlocked.
	// Return the message of skipped tables and error.
	RemoveLockedTables(tables map[int64]*StatsLockTable) (skipped string, err error)

	// RemoveLockedPartitions remove partitions from table locked records.
	// - tid: table id of which will be unlocked.
	// - tableName: table name of which will be unlocked.
	// - pidNames: partition ids of which will be unlocked.
	// Note: If the whole table is locked, then skip all partitions of the table.
	RemoveLockedPartitions(
		tid int64,
		tableName string,
		pidNames map[int64]string,
	) (skipped string, err error)

	// GetLockedTables returns the locked status of the given tables.
	// Note: This function query locked tables from store, so please try to batch the query.
	GetLockedTables(tableIDs ...int64) (map[int64]struct{}, error)

	// GetTableLockedAndClearForTest for unit test only.
	GetTableLockedAndClearForTest() (map[int64]struct{}, error)
}

StatsLock is used to manage locked stats.

type StatsLockTable

type StatsLockTable struct {
	PartitionInfo map[int64]string
	// schema name + table name.
	FullName string
}

StatsLockTable is the table info of which will be locked.

type StatsReadWriter

type StatsReadWriter interface {
	// TableStatsFromStorage loads table stats info from storage.
	TableStatsFromStorage(tableInfo *model.TableInfo, physicalID int64, loadAll bool, snapshot uint64) (statsTbl *statistics.Table, err error)

	// LoadTablePartitionStats loads partition stats info from storage.
	LoadTablePartitionStats(tableInfo *model.TableInfo, partitionDef *model.PartitionDefinition) (*statistics.Table, error)

	// StatsMetaCountAndModifyCount reads count and modify_count for the given table from mysql.stats_meta.
	StatsMetaCountAndModifyCount(tableID int64) (count, modifyCount int64, err error)

	// LoadNeededHistograms will load histograms for those needed columns/indices and put them into the cache.
	LoadNeededHistograms(is infoschema.InfoSchema) (err error)

	// ReloadExtendedStatistics drops the cache for extended statistics and reload data from mysql.stats_extended.
	ReloadExtendedStatistics() error

	// SaveStatsToStorage save the stats data to the storage.
	SaveStatsToStorage(tableID int64, count, modifyCount int64, isIndex int, hg *statistics.Histogram,
		cms *statistics.CMSketch, topN *statistics.TopN, statsVersion int, isAnalyzed int64, updateAnalyzeTime bool, source string) (err error)

	// SaveTableStatsToStorage saves the stats of a table to storage.
	SaveTableStatsToStorage(results *statistics.AnalyzeResults, analyzeSnapshot bool, source string) (err error)

	// SaveMetaToStorage saves the stats meta of a table to storage.
	SaveMetaToStorage(tableID, count, modifyCount int64, source string) (err error)

	// InsertColStats2KV inserts columns stats to kv.
	InsertColStats2KV(physicalID int64, colInfos []*model.ColumnInfo) (err error)

	// InsertTableStats2KV inserts a record standing for a new table to stats_meta and inserts some records standing for the
	// new columns and indices which belong to this table.
	InsertTableStats2KV(info *model.TableInfo, physicalID int64) (err error)

	// UpdateStatsVersion will set statistics version to the newest TS,
	// then tidb-server will reload automatic.
	UpdateStatsVersion() error

	// UpdateStatsMetaVersionForGC updates the version of mysql.stats_meta,
	// ensuring it is greater than the last garbage collection (GC) time.
	// The GC worker deletes old stats based on a safe time point,
	// calculated as now() - 10 * max(stats lease, ddl lease).
	// The range [last GC time, safe time point) is chosen to prevent
	// the simultaneous deletion of numerous stats, minimizing potential
	// performance issues.
	// This function ensures the version is updated beyond the last GC time,
	// allowing the GC worker to delete outdated stats.
	//
	// Explanation:
	// - ddl lease: 10
	// - stats lease: 3
	// - safe time point: now() - 10 * 10 = now() - 100
	// - now: 200
	// - last GC time: 90
	// - [last GC time, safe time point) = [90, 100)
	// - To trigger stats deletion, the version must be updated beyond 90.
	//
	// This safeguards scenarios where a table remains unchanged for an extended period.
	// For instance, if a table was created at time 90, and it's now time 200,
	// with the last GC time at 95 and the safe time point at 100,
	// updating the version beyond 95 ensures eventual deletion of stats.
	UpdateStatsMetaVersionForGC(physicalID int64) (err error)

	// ChangeGlobalStatsID changes the global stats ID.
	ChangeGlobalStatsID(from, to int64) (err error)

	// TableStatsToJSON dumps table stats to JSON.
	TableStatsToJSON(dbName string, tableInfo *model.TableInfo, physicalID int64, snapshot uint64) (*statsutil.JSONTable, error)

	// DumpStatsToJSON dumps statistic to json.
	DumpStatsToJSON(dbName string, tableInfo *model.TableInfo,
		historyStatsExec sqlexec.RestrictedSQLExecutor, dumpPartitionStats bool) (*statsutil.JSONTable, error)

	// DumpHistoricalStatsBySnapshot dumped json tables from mysql.stats_meta_history and mysql.stats_history.
	// As implemented in getTableHistoricalStatsToJSONWithFallback, if historical stats are nonexistent, it will fall back
	// to the latest stats, and these table names (and partition names) will be returned in fallbackTbls.
	DumpHistoricalStatsBySnapshot(
		dbName string,
		tableInfo *model.TableInfo,
		snapshot uint64,
	) (
		jt *statsutil.JSONTable,
		fallbackTbls []string,
		err error,
	)

	// DumpStatsToJSONBySnapshot dumps statistic to json.
	DumpStatsToJSONBySnapshot(dbName string, tableInfo *model.TableInfo, snapshot uint64, dumpPartitionStats bool) (*statsutil.JSONTable, error)

	// PersistStatsBySnapshot dumps statistic to json and call the function for each partition statistic to persist.
	// Notice:
	//  1. It might call the function `persist` with nil jsontable.
	//  2. It is only used by BR, so partitions' statistic are always dumped.
	PersistStatsBySnapshot(ctx context.Context, dbName string, tableInfo *model.TableInfo, snapshot uint64, persist PersistFunc) error

	// LoadStatsFromJSONConcurrently consumes concurrently the statistic task from `taskCh`.
	LoadStatsFromJSONConcurrently(ctx context.Context, tableInfo *model.TableInfo, taskCh chan *PartitionStatisticLoadTask, concurrencyForPartition int) error

	// LoadStatsFromJSON will load statistic from JSONTable, and save it to the storage.
	// In final, it will also udpate the stats cache.
	LoadStatsFromJSON(ctx context.Context, is infoschema.InfoSchema, jsonTbl *statsutil.JSONTable, concurrencyForPartition int) error

	// LoadStatsFromJSONNoUpdate will load statistic from JSONTable, and save it to the storage.
	LoadStatsFromJSONNoUpdate(ctx context.Context, is infoschema.InfoSchema, jsonTbl *statsutil.JSONTable, concurrencyForPartition int) error

	// InsertExtendedStats inserts a record into mysql.stats_extended and update version in mysql.stats_meta.
	InsertExtendedStats(statsName string, colIDs []int64, tp int, tableID int64, ifNotExists bool) (err error)

	// MarkExtendedStatsDeleted update the status of mysql.stats_extended to be `deleted` and the version of mysql.stats_meta.
	MarkExtendedStatsDeleted(statsName string, tableID int64, ifExists bool) (err error)

	// SaveExtendedStatsToStorage writes extended stats of a table into mysql.stats_extended.
	SaveExtendedStatsToStorage(tableID int64, extStats *statistics.ExtendedStatsColl, isLoad bool) (err error)
}

StatsReadWriter is used to read and write stats to the storage. TODO: merge and remove some methods.

type StatsSyncLoad

type StatsSyncLoad interface {
	// SendLoadRequests sends load requests to the channel.
	SendLoadRequests(sc *stmtctx.StatementContext, neededHistItems []model.StatsLoadItem, timeout time.Duration) error

	// SyncWaitStatsLoad will wait for the load requests to finish.
	SyncWaitStatsLoad(sc *stmtctx.StatementContext) error

	// AppendNeededItem appends a needed item to the channel.
	AppendNeededItem(task *NeededItemTask, timeout time.Duration) error

	// SubLoadWorker will start a goroutine to handle the load requests.
	SubLoadWorker(sctx sessionctx.Context, exit chan struct{}, exitWg *util.WaitGroupEnhancedWrapper)

	// HandleOneTask will handle one task.
	HandleOneTask(sctx sessionctx.Context, lastTask *NeededItemTask, exit chan struct{}) (task *NeededItemTask, err error)
}

StatsSyncLoad implement the sync-load feature.

type StatsUsage

type StatsUsage interface {

	// LoadColumnStatsUsage returns all columns' usage information.
	LoadColumnStatsUsage(loc *time.Location) (map[model.TableItemID]ColStatsTimeInfo, error)

	// GetPredicateColumns returns IDs of predicate columns, which are the columns whose stats are used(needed) when generating query plans.
	GetPredicateColumns(tableID int64) ([]int64, error)

	// CollectColumnsInExtendedStats returns IDs of the columns involved in extended stats.
	CollectColumnsInExtendedStats(tableID int64) ([]int64, error)

	IndexUsage

	// NewSessionStatsItem allocates a stats collector for a session.
	// TODO: use interface{} to avoid cycle import, remove this interface{}.
	NewSessionStatsItem() any

	// ResetSessionStatsList resets the sessions stats list.
	ResetSessionStatsList()

	// DumpStatsDeltaToKV sweeps the whole list and updates the global map, then we dumps every table that held in map to KV.
	DumpStatsDeltaToKV(dumpAll bool) error

	// DumpColStatsUsageToKV sweeps the whole list, updates the column stats usage map and dumps it to KV.
	DumpColStatsUsageToKV() error
}

StatsUsage is used to track the usage of column / index statistics.