statistics: fix unnecessary index fmsketch loading (#42074) (#45083)

close #42052
pingcap · Jul 1, 2023 · c71f045 · c71f045
1 parent efc5387
commit c71f045
Show file tree

Hide file tree

Showing 2 changed files with 35 additions and 5 deletions.
diff --git a/statistics/handle/handle.go b/statistics/handle/handle.go
@@ -758,7 +758,7 @@ func (h *Handle) fmSketchFromStorage(reader *statsReader, tblID int64, isIndex,
 	return statistics.DecodeFMSketch(rows[0].GetBytes(0))
 }
 
-func (h *Handle) indexStatsFromStorage(reader *statsReader, row chunk.Row, table *statistics.Table, tableInfo *model.TableInfo) error {
+func (h *Handle) indexStatsFromStorage(reader *statsReader, row chunk.Row, table *statistics.Table, tableInfo *model.TableInfo, loadAll bool) error {
 	histID := row.GetInt64(2)
 	distinct := row.GetInt64(3)
 	histVer := row.GetUint64(4)
@@ -785,9 +785,14 @@ func (h *Handle) indexStatsFromStorage(reader *statsReader, row chunk.Row, table
 			if err != nil {
 				return errors.Trace(err)
 			}
-			fmSketch, err := h.fmSketchFromStorage(reader, table.PhysicalID, 1, histID)
-			if err != nil {
-				return errors.Trace(err)
+			var fmSketch *statistics.FMSketch
+			if loadAll {
+				// FMSketch is only used when merging partition stats into global stats. When merging partition stats into global stats,
+				// we load all the statistics, i.e., loadAll is true.
+				fmSketch, err = h.fmSketchFromStorage(reader, table.PhysicalID, 1, histID)
+				if err != nil {
+					return errors.Trace(err)
+				}
 			}
 			idx = &statistics.Index{Histogram: *hg, CMSketch: cms, TopN: topN, FMSketch: fmSketch, Info: idxInfo, ErrorRate: errorRate, StatsVer: row.GetInt64(7), Flag: flag}
 			lastAnalyzePos.Copy(&idx.LastAnalyzePos)
@@ -948,7 +953,7 @@ func (h *Handle) TableStatsFromStorage(tableInfo *model.TableInfo, physicalID in
 	}
 	for _, row := range rows {
 		if row.GetInt64(1) > 0 {
-			err = h.indexStatsFromStorage(reader, row, table, tableInfo)
+			err = h.indexStatsFromStorage(reader, row, table, tableInfo, loadAll)
 		} else {
 			err = h.columnStatsFromStorage(reader, row, table, tableInfo, loadAll)
 		}

diff --git a/statistics/integration_test.go b/statistics/integration_test.go
@@ -642,3 +642,28 @@ func TestCrossValidationSelectivity(t *testing.T) {
 		"└─Selection 0.00 cop[tikv]  gt(test.t.c, 1000)",
 		"  └─TableRangeScan 2.00 cop[tikv] table:t range:(1 0,1 1000), keep order:false"))
 }
+
+func TestUpdateNotLoadIndexFMSketch(t *testing.T) {
+	store, dom, clean := testkit.CreateMockStoreAndDomain(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	h := dom.StatsHandle()
+	tk.MustExec("use test")
+	tk.MustExec("create table t(a int, b int, index idx(a)) partition by range (a) (partition p0 values less than (10),partition p1 values less than maxvalue)")
+	tk.MustExec("insert into t values (1,2), (3,4), (5,6), (7,8)")
+	require.NoError(t, h.HandleDDLEvent(<-h.DDLEventCh()))
+	tk.MustExec("analyze table t")
+	is := dom.InfoSchema()
+	tbl, err := is.TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
+	require.NoError(t, err)
+	tblInfo := tbl.Meta()
+	idxInfo := tblInfo.Indices[0]
+	p0 := tblInfo.Partition.Definitions[0]
+	p1 := tblInfo.Partition.Definitions[1]
+	require.Nil(t, h.GetPartitionStats(tblInfo, p0.ID).Indices[idxInfo.ID].FMSketch)
+	require.Nil(t, h.GetPartitionStats(tblInfo, p1.ID).Indices[idxInfo.ID].FMSketch)
+	h.Clear()
+	require.NoError(t, h.Update(is))
+	require.Nil(t, h.GetPartitionStats(tblInfo, p0.ID).Indices[idxInfo.ID].FMSketch)
+	require.Nil(t, h.GetPartitionStats(tblInfo, p1.ID).Indices[idxInfo.ID].FMSketch)
+}