stats: fix shallow copy bugs (pingcap#12691) (pingcap#12817)

Author: sre-bot

statistics/cmsketch.go

@@ -445,7 +445,9 @@ func LoadCMSketchWithTopN(exec sqlexec.RestrictedSQLExecutor, tableID, isIndex,
 	}
 	topN := make([]*TopNMeta, 0, len(topNRows))
 	for _, row := range topNRows {
-		topN = append(topN, &TopNMeta{Data: row.GetBytes(0), Count: row.GetUint64(1)})
+		data := make([]byte, len(row.GetBytes(0)))
+		copy(data, row.GetBytes(0))
+		topN = append(topN, &TopNMeta{Data: data, Count: row.GetUint64(1)})
 	}
 	return decodeCMSketch(cms, topN)
 }

statistics/handle/bootstrap.go

@@ -91,6 +91,7 @@ func (h *Handle) initStatsHistograms4Chunk(is infoschema.InfoSchema, tables Stat
 			continue
 		}
 		id, ndv, nullCount, version, totColSize := row.GetInt64(2), row.GetInt64(3), row.GetInt64(5), row.GetUint64(4), row.GetInt64(7)
+		lastAnalyzePos := row.GetDatum(11, types.NewFieldType(mysql.TypeBlob))
 		tbl, _ := h.getTableByPhysicalID(is, table.PhysicalID)
 		if row.GetInt64(1) > 0 {
 			var idxInfo *model.IndexInfo
@@ -109,7 +110,7 @@ func (h *Handle) initStatsHistograms4Chunk(is infoschema.InfoSchema, tables Stat
 				terror.Log(errors.Trace(err))
 			}
 			hist := statistics.NewHistogram(id, ndv, nullCount, version, types.NewFieldType(mysql.TypeBlob), chunk.InitialCapacity, 0)
-			table.Indices[hist.ID] = &statistics.Index{Histogram: *hist, CMSketch: cms, Info: idxInfo, StatsVer: row.GetInt64(8), Flag: row.GetInt64(10), LastAnalyzePos: row.GetDatum(11, types.NewFieldType(mysql.TypeBlob))}
+			table.Indices[hist.ID] = &statistics.Index{Histogram: *hist, CMSketch: cms, Info: idxInfo, StatsVer: row.GetInt64(8), Flag: row.GetInt64(10), LastAnalyzePos: *lastAnalyzePos.Copy()}
 		} else {
 			var colInfo *model.ColumnInfo
 			for _, col := range tbl.Meta().Columns {
@@ -130,7 +131,7 @@ func (h *Handle) initStatsHistograms4Chunk(is infoschema.InfoSchema, tables Stat
 				Count:          nullCount,
 				IsHandle:       tbl.Meta().PKIsHandle && mysql.HasPriKeyFlag(colInfo.Flag),
 				Flag:           row.GetInt64(10),
-				LastAnalyzePos: row.GetDatum(11, types.NewFieldType(mysql.TypeBlob)),
+				LastAnalyzePos: *lastAnalyzePos.Copy(),
 			}
 		}
 	}

statistics/handle/handle.go

@@ -83,7 +83,8 @@ func (h *Handle) Clear() {
 	}
 	h.feedback = h.feedback[:0]
 	h.mu.ctx.GetSessionVars().InitChunkSize = 1
-	h.mu.ctx.GetSessionVars().MaxChunkSize = 32
+	h.mu.ctx.GetSessionVars().MaxChunkSize = 1
+	h.mu.ctx.GetSessionVars().ProjectionConcurrency = 0
 	h.listHead = &SessionStatsCollector{mapper: make(tableDeltaMap), rateMap: make(errorRateDeltaMap)}
 	h.globalMap = make(tableDeltaMap)
 	h.mu.rateMap = make(errorRateDeltaMap)
@@ -353,6 +354,7 @@ func (h *Handle) indexStatsFromStorage(row chunk.Row, table *statistics.Table, t
 	idx := table.Indices[histID]
 	errorRate := statistics.ErrorRate{}
 	flag := row.GetInt64(8)
+	lastAnalyzePos := row.GetDatum(10, types.NewFieldType(mysql.TypeBlob))
 	if statistics.IsAnalyzed(flag) {
 		h.mu.Lock()
 		h.mu.rateMap.clear(table.PhysicalID, histID, true)
@@ -373,7 +375,7 @@ func (h *Handle) indexStatsFromStorage(row chunk.Row, table *statistics.Table, t
 			if err != nil {
 				return errors.Trace(err)
 			}
-			idx = &statistics.Index{Histogram: *hg, CMSketch: cms, Info: idxInfo, ErrorRate: errorRate, StatsVer: row.GetInt64(7), Flag: flag, LastAnalyzePos: row.GetDatum(10, types.NewFieldType(mysql.TypeBlob))}
+			idx = &statistics.Index{Histogram: *hg, CMSketch: cms, Info: idxInfo, ErrorRate: errorRate, StatsVer: row.GetInt64(7), Flag: flag, LastAnalyzePos: *lastAnalyzePos.Copy()}
 		}
 		break
 	}
@@ -392,6 +394,7 @@ func (h *Handle) columnStatsFromStorage(row chunk.Row, table *statistics.Table,
 	nullCount := row.GetInt64(5)
 	totColSize := row.GetInt64(6)
 	correlation := row.GetFloat64(9)
+	lastAnalyzePos := row.GetDatum(10, types.NewFieldType(mysql.TypeBlob))
 	col := table.Columns[histID]
 	errorRate := statistics.ErrorRate{}
 	flag := row.GetInt64(8)
@@ -429,7 +432,7 @@ func (h *Handle) columnStatsFromStorage(row chunk.Row, table *statistics.Table,
 				ErrorRate:      errorRate,
 				IsHandle:       tableInfo.PKIsHandle && mysql.HasPriKeyFlag(colInfo.Flag),
 				Flag:           flag,
-				LastAnalyzePos: row.GetDatum(10, types.NewFieldType(mysql.TypeBlob)),
+				LastAnalyzePos: *lastAnalyzePos.Copy(),
 			}
 			col.Histogram.Correlation = correlation
 			break
@@ -452,7 +455,7 @@ func (h *Handle) columnStatsFromStorage(row chunk.Row, table *statistics.Table,
 				ErrorRate:      errorRate,
 				IsHandle:       tableInfo.PKIsHandle && mysql.HasPriKeyFlag(colInfo.Flag),
 				Flag:           flag,
-				LastAnalyzePos: row.GetDatum(10, types.NewFieldType(mysql.TypeBlob)),
+				LastAnalyzePos: *lastAnalyzePos.Copy(),
 			}
 			break
 		}

statistics/handle/handle_test.go

@@ -371,7 +371,7 @@ func (s *testStatsSuite) TestInitStats(c *C) {
 	testKit := testkit.NewTestKit(c, s.store)
 	testKit.MustExec("use test")
 	testKit.MustExec("create table t(a int, b int, c int, primary key(a), key idx(b))")
-	testKit.MustExec("insert into t values (1,1,1),(2,2,2),(3,3,3),(4,4,4),(5,5,5),(6,6,6)")
+	testKit.MustExec("insert into t values (1,1,1),(2,2,2),(3,3,3),(4,4,4),(5,5,5),(6,7,8)")
 	testKit.MustExec("analyze table t")
 	h := s.do.StatsHandle()
 	is := s.do.InfoSchema()
@@ -384,6 +384,10 @@ func (s *testStatsSuite) TestInitStats(c *C) {
 	h.Clear()
 	c.Assert(h.InitStats(is), IsNil)
 	table0 := h.GetTableStats(tbl.Meta())
+	cols := table0.Columns
+	c.Assert(cols[1].LastAnalyzePos.GetBytes()[0], Equals, uint8(0x36))
+	c.Assert(cols[2].LastAnalyzePos.GetBytes()[0], Equals, uint8(0x37))
+	c.Assert(cols[3].LastAnalyzePos.GetBytes()[0], Equals, uint8(0x38))
 	h.Clear()
 	c.Assert(h.Update(is), IsNil)
 	table1 := h.GetTableStats(tbl.Meta())