stats: fix panic when dumping stats (#8448) (#8464)

pingcap · Nov 28, 2018 · ced80e5 · ced80e5
1 parent f5dd339
commit ced80e5
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Showing 3 changed files with 33 additions and 13 deletions.
diff --git a/statistics/dump_test.go b/statistics/dump_test.go
@@ -18,6 +18,7 @@ import (
 	"github.com/pingcap/tidb/domain"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/model"
+	"github.com/pingcap/tidb/statistics"
 	"github.com/pingcap/tidb/util/testkit"
 	"github.com/pingcap/tidb/util/testleak"
 )
@@ -64,3 +65,29 @@ func (s *testDumpStatsSuite) TestConversion(c *C) {
 	tbl := h.GetTableStats(tableInfo.Meta())
 	assertTableEqual(c, loadTbl, tbl)
 }
+
+func (s *testDumpStatsSuite) TestDumpAlteredTable(c *C) {
+	defer cleanEnv(c, s.store, s.do)
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	h := s.do.StatsHandle()
+	oriLease := h.Lease
+	h.Lease = 1
+	defer func() { h.Lease = oriLease }()
+	tk.MustExec("create table t(a int, b int)")
+	h.HandleDDLEvent(<-h.DDLEventCh())
+	tk.MustExec("analyze table t")
+	t := <-h.AnalyzeResultCh()
+	h.Update(s.do.InfoSchema())
+	for i, hg := range t.Hist {
+		err := statistics.SaveStatsToStorage(tk.Se, t.TableID, t.Count, t.IsIndex, hg, t.Cms[i])
+		c.Assert(err, IsNil)
+	}
+	h.Update(s.do.InfoSchema())
+	tk.MustExec("alter table t drop column a")
+	table, err := s.do.InfoSchema().TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
+	c.Assert(err, IsNil)
+	_, err = h.DumpStatsToJSON("test", table.Meta())
+	c.Assert(err, IsNil)
+}
diff --git a/statistics/histogram.go b/statistics/histogram.go
@@ -366,7 +366,7 @@ func (hg *Histogram) greaterAndEqRowCount(value types.Datum) float64 {
 // lessRowCount estimates the row count where the column less than value.
 func (hg *Histogram) lessRowCount(value types.Datum) float64 {
 	// all the values is null
-	if hg.Bounds == nil {
+	if hg.Bounds.NumRows() == 0 {
 		return 0
 	}
 	index, match := hg.Bounds.LowerBound(0, &value)
@@ -642,7 +642,7 @@ func (c *Column) equalRowCount(sc *stmtctx.StatementContext, val types.Datum, mo
 		return float64(c.NullCount), nil
 	}
 	// all the values is null
-	if c.Histogram.Bounds == nil {
+	if c.Histogram.Bounds.NumRows() == 0 {
 		return 0.0, nil
 	}
 	if c.NDV > 0 && c.outOfRange(val) {

diff --git a/statistics/table.go b/statistics/table.go
@@ -140,17 +140,10 @@ func (h *Handle) columnStatsFromStorage(row types.Row, table *Table, tableInfo *
 				return errors.Trace(err)
 			}
 			col = &Column{
-				Histogram: Histogram{
-					ID:                histID,
-					NDV:               distinct,
-					NullCount:         nullCount,
-					tp:                &colInfo.FieldType,
-					LastUpdateVersion: histVer,
-					TotColSize:        totColSize,
-				},
-				Info:     colInfo,
-				Count:    count + nullCount,
-				isHandle: tableInfo.PKIsHandle && mysql.HasPriKeyFlag(colInfo.Flag),
+				Histogram: *NewHistogram(histID, distinct, nullCount, histVer, &colInfo.FieldType, 0, totColSize),
+				Info:      colInfo,
+				Count:     count + nullCount,
+				isHandle:  tableInfo.PKIsHandle && mysql.HasPriKeyFlag(colInfo.Flag),
 			}
 			break
 		}