Files
tidb/pkg/statistics/handle/usage/predicate_column.go
2024-06-24 06:56:56 +00:00

195 lines
7.2 KiB
Go

// Copyright 2023 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package usage
import (
"encoding/json"
"fmt"
"time"
"github.com/pingcap/errors"
"github.com/pingcap/tidb/pkg/infoschema"
"github.com/pingcap/tidb/pkg/parser/model"
"github.com/pingcap/tidb/pkg/parser/mysql"
"github.com/pingcap/tidb/pkg/sessionctx"
"github.com/pingcap/tidb/pkg/statistics"
statstypes "github.com/pingcap/tidb/pkg/statistics/handle/types"
"github.com/pingcap/tidb/pkg/statistics/handle/usage/indexusage"
utilstats "github.com/pingcap/tidb/pkg/statistics/handle/util"
"github.com/pingcap/tidb/pkg/types"
"github.com/pingcap/tidb/pkg/util/logutil"
"go.uber.org/zap"
)
// statsUsageImpl implements statstypes.StatsUsage.
type statsUsageImpl struct {
statsHandle statstypes.StatsHandle
// idxUsageCollector contains all the index usage collectors required by session.
idxUsageCollector *indexusage.Collector
// SessionStatsList contains all the stats collector required by session.
*SessionStatsList
}
// NewStatsUsageImpl creates a statstypes.StatsUsage.
func NewStatsUsageImpl(statsHandle statstypes.StatsHandle) statstypes.StatsUsage {
return &statsUsageImpl{
statsHandle: statsHandle,
idxUsageCollector: indexusage.NewCollector(),
SessionStatsList: NewSessionStatsList()}
}
// LoadColumnStatsUsage returns all columns' usage information.
func (u *statsUsageImpl) LoadColumnStatsUsage(loc *time.Location) (colStatsMap map[model.TableItemID]statstypes.ColStatsTimeInfo, err error) {
err = utilstats.CallWithSCtx(u.statsHandle.SPool(), func(sctx sessionctx.Context) error {
colStatsMap, err = LoadColumnStatsUsage(sctx, loc)
return err
})
return
}
// GetPredicateColumns returns IDs of predicate columns, which are the columns whose stats are used(needed) when generating query plans.
func (u *statsUsageImpl) GetPredicateColumns(tableID int64) (columnIDs []int64, err error) {
err = utilstats.CallWithSCtx(u.statsHandle.SPool(), func(sctx sessionctx.Context) error {
columnIDs, err = GetPredicateColumns(sctx, tableID)
return err
}, utilstats.FlagWrapTxn)
return
}
// CollectColumnsInExtendedStats returns IDs of the columns involved in extended stats.
func (u *statsUsageImpl) CollectColumnsInExtendedStats(tableID int64) (columnIDs []int64, err error) {
err = utilstats.CallWithSCtx(u.statsHandle.SPool(), func(sctx sessionctx.Context) error {
columnIDs, err = CollectColumnsInExtendedStats(sctx, tableID)
return err
})
return
}
// LoadColumnStatsUsage loads column stats usage information from disk.
func LoadColumnStatsUsage(sctx sessionctx.Context, loc *time.Location) (map[model.TableItemID]statstypes.ColStatsTimeInfo, error) {
// Since we use another session from session pool to read mysql.column_stats_usage, which may have different @@time_zone, so we do time zone conversion here.
rows, _, err := utilstats.ExecRows(sctx, "SELECT table_id, column_id, CONVERT_TZ(last_used_at, @@TIME_ZONE, '+00:00'), CONVERT_TZ(last_analyzed_at, @@TIME_ZONE, '+00:00') FROM mysql.column_stats_usage")
if err != nil {
return nil, errors.Trace(err)
}
colStatsMap := make(map[model.TableItemID]statstypes.ColStatsTimeInfo, len(rows))
for _, row := range rows {
if row.IsNull(0) || row.IsNull(1) {
continue
}
tblColID := model.TableItemID{TableID: row.GetInt64(0), ID: row.GetInt64(1), IsIndex: false}
var statsUsage statstypes.ColStatsTimeInfo
if !row.IsNull(2) {
gt, err := row.GetTime(2).GoTime(time.UTC)
if err != nil {
return nil, errors.Trace(err)
}
t := types.NewTime(types.FromGoTime(gt.In(loc)), mysql.TypeTimestamp, types.DefaultFsp)
statsUsage.LastUsedAt = &t
}
if !row.IsNull(3) {
gt, err := row.GetTime(3).GoTime(time.UTC)
if err != nil {
return nil, errors.Trace(err)
}
t := types.NewTime(types.FromGoTime(gt.In(loc)), mysql.TypeTimestamp, types.DefaultFsp)
statsUsage.LastAnalyzedAt = &t
}
colStatsMap[tblColID] = statsUsage
}
return colStatsMap, nil
}
// GetPredicateColumns returns IDs of predicate columns, which are the columns whose stats are used(needed) when generating query plans.
func GetPredicateColumns(sctx sessionctx.Context, tableID int64) ([]int64, error) {
// Each time we retrieve the predicate columns, we also attempt to remove any column stats usage information whose column is dropped.
err := cleanupDroppedColumnStatsUsage(sctx, tableID)
if err != nil {
return nil, errors.Trace(err)
}
rows, _, err := utilstats.ExecRows(
sctx,
"SELECT column_id, CONVERT_TZ(last_used_at, @@TIME_ZONE, '+00:00') FROM mysql.column_stats_usage WHERE table_id = %? AND last_used_at IS NOT NULL",
tableID,
)
if err != nil {
return nil, errors.Trace(err)
}
columnIDs := make([]int64, 0, len(rows))
for _, row := range rows {
// Usually, it should not be NULL.
// This only happens when the last_used_at is not a valid time.
if row.IsNull(1) {
continue
}
colID := row.GetInt64(0)
columnIDs = append(columnIDs, colID)
}
return columnIDs, nil
}
// cleanupDroppedColumnStatsUsage deletes the column stats usage information whose column is dropped.
func cleanupDroppedColumnStatsUsage(sctx sessionctx.Context, tableID int64) error {
is := sctx.GetDomainInfoSchema().(infoschema.InfoSchema)
table, ok := is.TableByID(tableID)
if !ok {
// Usually, it should not happen.
// But if it happens, we can safely do nothing.
return nil
}
allColumns := table.Meta().Columns
// Due to SQL limitations, column IDs must be converted to strings for proper escaping in the query :(
columnIDs := make([]string, 0, len(allColumns))
for _, col := range allColumns {
columnIDs = append(columnIDs, fmt.Sprintf("%d", col.ID))
}
// Delete the column stats usage information whose column is dropped.
_, _, err := utilstats.ExecRows(
sctx,
"DELETE FROM mysql.column_stats_usage WHERE table_id = %? AND column_id NOT IN (%?)",
tableID,
columnIDs,
)
return err
}
// CollectColumnsInExtendedStats returns IDs of the columns involved in extended stats.
func CollectColumnsInExtendedStats(sctx sessionctx.Context, tableID int64) ([]int64, error) {
const sql = "SELECT name, type, column_ids FROM mysql.stats_extended WHERE table_id = %? and status in (%?, %?)"
rows, _, err := utilstats.ExecRows(sctx, sql, tableID, statistics.ExtendedStatsAnalyzed, statistics.ExtendedStatsInited)
if err != nil {
return nil, errors.Trace(err)
}
if len(rows) == 0 {
return nil, nil
}
columnIDs := make([]int64, 0, len(rows)*2)
for _, row := range rows {
twoIDs := make([]int64, 0, 2)
data := row.GetString(2)
err := json.Unmarshal([]byte(data), &twoIDs)
if err != nil {
logutil.BgLogger().Error("invalid column_ids in mysql.stats_extended, skip collecting extended stats for this row", zap.String("column_ids", data), zap.Error(err))
continue
}
columnIDs = append(columnIDs, twoIDs...)
}
return columnIDs, nil
}