statistics: support gc outdated historical stats

executor/historical_stats_test.go

@@ -19,8 +19,10 @@ import (
 	"fmt"
 	"strconv"
 	"testing"
+	"time"
 
 	"github.com/pingcap/tidb/parser/model"
+	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/statistics/handle"
 	"github.com/pingcap/tidb/testkit"
 	"github.com/stretchr/testify/require"
@@ -178,3 +180,38 @@ func TestGCHistoryStatsAfterDropTable(t *testing.T) {
 	tk.MustQuery(fmt.Sprintf("select count(*) from mysql.stats_history where table_id = '%d'",
 		tableInfo.Meta().ID)).Check(testkit.Rows("0"))
 }
+
+func TestGCOutdatedHistoryStats(t *testing.T) {
+	store, dom := testkit.CreateMockStoreAndDomain(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("set global tidb_enable_historical_stats = 1")
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a int, b varchar(10))")
+	tk.MustExec("analyze table test.t")
+	is := dom.InfoSchema()
+	tableInfo, err := is.TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
+	require.NoError(t, err)
+	// dump historical stats
+	h := dom.StatsHandle()
+	hsWorker := dom.GetHistoricalStatsWorker()
+	tblID := hsWorker.GetOneHistoricalStatsTable()
+	err = hsWorker.DumpHistoricalStats(tblID, h)
+	require.Nil(t, err)
+
+	// assert the records of history stats table
+	tk.MustQuery(fmt.Sprintf("select count(*) from mysql.stats_meta_history where table_id = '%d' order by create_time",
+		tableInfo.Meta().ID)).Check(testkit.Rows("1"))
+	tk.MustQuery(fmt.Sprintf("select count(*) from mysql.stats_history where table_id = '%d'",
+		tableInfo.Meta().ID)).Check(testkit.Rows("1"))
+
+	variable.HistoricalStatsDuration.Store(1 * time.Second)
+	time.Sleep(2 * time.Second)
+	err = dom.StatsHandle().ClearOutdatedHistoryStats()
+	require.NoError(t, err)
+	// assert the records of history stats table
+	tk.MustQuery(fmt.Sprintf("select count(*) from mysql.stats_meta_history where table_id = '%d' order by create_time",
+		tableInfo.Meta().ID)).Check(testkit.Rows("0"))
+	tk.MustQuery(fmt.Sprintf("select count(*) from mysql.stats_history where table_id = '%d'",
+		tableInfo.Meta().ID)).Check(testkit.Rows("0"))
+}

sessionctx/variable/sysvar.go

@@ -1169,6 +1169,18 @@ var defaultSysVars = []*SysVar{
 		return nil
 	}},
 
+	{Scope: ScopeGlobal, Name: TiDBHistoricalStatsDuration, Value: DefTiDBHistoricalStatsDuration.String(), Type: TypeDuration, MinValue: int64(time.Minute * 10), MaxValue: uint64(time.Hour * 24 * 365),
+		GetGlobal: func(ctx context.Context, vars *SessionVars) (string, error) {
+			return HistoricalStatsDuration.Load().String(), nil
+		}, SetGlobal: func(ctx context.Context, vars *SessionVars, s string) error {
+			d, err := time.ParseDuration(s)
+			if err != nil {
+				return err
+			}
+			HistoricalStatsDuration.Store(d)
+			return nil
+		}},
+
 	/* The system variables below have GLOBAL and SESSION scope  */
 	{Scope: ScopeGlobal | ScopeSession, Name: TiDBEnablePlanReplayerCapture, Value: BoolToOnOff(false), Type: TypeBool,
 		SetSession: func(s *SessionVars, val string) error {

sessionctx/variable/tidb_vars.go

@@ -895,6 +895,8 @@ const (
 	PasswordReuseHistory = "password_history"
 	// PasswordReuseTime limit how long passwords can be reused.
 	PasswordReuseTime = "password_reuse_interval"
+	// TiDBHistoricalStatsDuration indicates the duration to remain tidb historical stats
+	TiDBHistoricalStatsDuration = "tidb_historical_stats_duration"
 )
 
 // TiDB intentional limits
@@ -1150,6 +1152,7 @@ const (
 	DefPasswordReuseHistory                          = 0
 	DefPasswordReuseTime                             = 0
 	DefTiDBStoreBatchSize                            = 0
+	DefTiDBHistoricalStatsDuration                   = 7 * 24 * time.Hour
 	DefTiDBTTLJobRunInterval                         = "1h0m0s"
 	DefTiDBTTLJobScheduleWindowStartTime             = "00:00 +0000"
 	DefTiDBTTLJobScheduleWindowEndTime               = "23:59 +0000"
@@ -1230,6 +1233,7 @@ var (
 	PasswordHistory                    = atomic.NewInt64(DefPasswordReuseHistory)
 	PasswordReuseInterval              = atomic.NewInt64(DefPasswordReuseTime)
 	IsSandBoxModeEnabled               = atomic.NewBool(false)
+	HistoricalStatsDuration            = atomic.NewDuration(DefTiDBHistoricalStatsDuration)
 )
 
 var (

statistics/handle/gc.go

@@ -22,6 +22,7 @@ import (
 	"github.com/pingcap/errors"
 	"github.com/pingcap/tidb/infoschema"
 	"github.com/pingcap/tidb/kv"
+	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/util/logutil"
 	"github.com/pingcap/tidb/util/mathutil"
 	"github.com/pingcap/tidb/util/sqlexec"
@@ -54,6 +55,11 @@ func (h *Handle) GCStats(is infoschema.InfoSchema, ddlLease time.Duration) error
 			return errors.Trace(err)
 		}
 	}
+	if err := h.ClearOutdatedHistoryStats(); err != nil {
+		logutil.BgLogger().Warn("failed to gc outdated historical stats",
+			zap.Duration("duration", variable.HistoricalStatsDuration.Load()),
+			zap.Error(err))
+	}
 	return h.removeDeletedExtendedStats(gcVer)
 }
 
@@ -141,6 +147,22 @@ func (h *Handle) gcTableStats(is infoschema.InfoSchema, physicalID int64) error
 	return nil
 }
 
+// ClearOutdatedHistoryStats clear outdated historical stats
+func (h *Handle) ClearOutdatedHistoryStats() error {
+	ctx := kv.WithInternalSourceType(context.Background(), kv.InternalTxnStats)
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	exec := h.mu.ctx.(sqlexec.SQLExecutor)
+	sql := "delete from mysql.stats_meta_history where NOW() - create_time >= %?"
+	_, err := exec.ExecuteInternal(ctx, sql, variable.HistoricalStatsDuration.Load().Seconds())
+	if err != nil {
+		return err
+	}
+	sql = "delete from mysql.stats_history where NOW() - create_time >= %? "
+	_, err = exec.ExecuteInternal(ctx, sql, variable.HistoricalStatsDuration.Load().Seconds())
+	return err
+}
+
 func (h *Handle) gcHistoryStatsFromKV(physicalID int64) error {
 	h.mu.Lock()
 	defer h.mu.Unlock()