executor: add historical stats test and make it enabled

executor/historical_stats_test.go

@@ -174,6 +174,7 @@ func TestGCHistoryStatsAfterDropTable(t *testing.T) {
 		tableInfo.Meta().ID)).Check(testkit.Rows("1"))
 	// drop the table and gc stats
 	tk.MustExec("drop table t")
+	is = dom.InfoSchema()
 	h.GCStats(is, 0)
 
 	// assert stats_history tables delete the record of dropped table
@@ -183,6 +184,51 @@ func TestGCHistoryStatsAfterDropTable(t *testing.T) {
 		tableInfo.Meta().ID)).Check(testkit.Rows("0"))
 }
 
+func TestAssertHistoricalStatsAfterAlterTable(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),c int, KEY `idx` (`c`))")
+	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)
+
+	time.Sleep(1 * time.Second)
+	snapshot := oracle.GoTimeToTS(time.Now())
+	jsTable, err := h.DumpHistoricalStatsBySnapshot("test", tableInfo.Meta(), snapshot)
+	require.NoError(t, err)
+	require.NotNil(t, jsTable)
+	require.NotEqual(t, jsTable.Version, uint64(0))
+	originVersion := jsTable.Version
+
+	// assert historical stats non-change after drop column
+	tk.MustExec("alter table t drop column b")
+	h.GCStats(is, 0)
+	snapshot = oracle.GoTimeToTS(time.Now())
+	jsTable, err = h.DumpHistoricalStatsBySnapshot("test", tableInfo.Meta(), snapshot)
+	require.NoError(t, err)
+	require.NotNil(t, jsTable)
+	require.Equal(t, jsTable.Version, originVersion)
+
+	// assert historical stats non-change after drop index
+	tk.MustExec("alter table t drop index idx")
+	h.GCStats(is, 0)
+	snapshot = oracle.GoTimeToTS(time.Now())
+	jsTable, err = h.DumpHistoricalStatsBySnapshot("test", tableInfo.Meta(), snapshot)
+	require.NoError(t, err)
+	require.NotNil(t, jsTable)
+	require.Equal(t, jsTable.Version, originVersion)
+}
+
 func TestGCOutdatedHistoryStats(t *testing.T) {
 	store, dom := testkit.CreateMockStoreAndDomain(t)
 	tk := testkit.NewTestKit(t, store)

executor/set_test.go

@@ -645,7 +645,7 @@ func TestSetVar(t *testing.T) {
 	tk.MustQuery("select @@tidb_enable_tso_follower_proxy").Check(testkit.Rows("0"))
 	require.Error(t, tk.ExecToErr("set tidb_enable_tso_follower_proxy = 1"))
 
-	tk.MustQuery("select @@tidb_enable_historical_stats").Check(testkit.Rows("0"))
+	tk.MustQuery("select @@tidb_enable_historical_stats").Check(testkit.Rows("1"))
 	tk.MustExec("set global tidb_enable_historical_stats = 1")
 	tk.MustQuery("select @@tidb_enable_historical_stats").Check(testkit.Rows("1"))
 	tk.MustExec("set global tidb_enable_historical_stats = 0")

sessionctx/variable/sysvar.go

@@ -731,7 +731,7 @@ var defaultSysVars = []*SysVar{
 		return nil
 	}},
 	{Scope: ScopeGlobal, Name: TiDBEnableTelemetry, Value: BoolToOnOff(DefTiDBEnableTelemetry), Type: TypeBool},
-	{Scope: ScopeGlobal, Name: TiDBEnableHistoricalStats, Value: Off, Type: TypeBool},
+	{Scope: ScopeGlobal, Name: TiDBEnableHistoricalStats, Value: On, Type: TypeBool},
 	/* tikv gc metrics */
 	{Scope: ScopeGlobal, Name: TiDBGCEnable, Value: On, Type: TypeBool, GetGlobal: func(_ context.Context, s *SessionVars) (string, error) {
 		return getTiDBTableValue(s, "tikv_gc_enable", On)

statistics/handle/gc.go

@@ -53,8 +53,11 @@ func (h *Handle) GCStats(is infoschema.InfoSchema, ddlLease time.Duration) error
 		if err := h.gcTableStats(is, row.GetInt64(0)); err != nil {
 			return errors.Trace(err)
 		}
-		if err := h.gcHistoryStatsFromKV(row.GetInt64(0)); err != nil {
-			return errors.Trace(err)
+		_, existed := is.TableByID(row.GetInt64(0))
+		if !existed {
+			if err := h.gcHistoryStatsFromKV(row.GetInt64(0)); err != nil {
+				return errors.Trace(err)
+			}
 		}
 	}
 	if err := h.ClearOutdatedHistoryStats(); err != nil {