stats: fix auto analyze trigger condition

statistics/update.go

@@ -586,10 +586,10 @@ const (
 // AutoAnalyzeMinCnt means if the count of table is less than this value, we needn't do auto analyze.
 var AutoAnalyzeMinCnt int64 = 1000
 
-// tableAnalyzed checks if the table is analyzed.
-func tableAnalyzed(tbl *Table) bool {
+// TableAnalyzed checks if the table is analyzed.
+func TableAnalyzed(tbl *Table) bool {
 	for _, col := range tbl.Columns {
-		if col.Histogram.Len() > 0 {
+		if col.Count > 0 {
 			return true
 		}
 	}
@@ -607,7 +607,7 @@ func tableAnalyzed(tbl *Table) bool {
 // 2. If the table had been analyzed before, we need to analyze it when
 //    "tbl.ModifyCount/tbl.Count > autoAnalyzeRatio".
 func needAnalyzeTable(tbl *Table, limit time.Duration, autoAnalyzeRatio float64) bool {
-	analyzed := tableAnalyzed(tbl)
+	analyzed := TableAnalyzed(tbl)
 	if !analyzed {
 		t := time.Unix(0, oracle.ExtractPhysical(tbl.Version)*int64(time.Millisecond))
 		return time.Since(t) >= limit

statistics/update_test.go

@@ -405,6 +405,40 @@ func (s *testStatsUpdateSuite) TestAutoUpdate(c *C) {
 	c.Assert(hg.Len(), Equals, 3)
 }
 
+func (s *testStatsUpdateSuite) TestTableAnalyzed(c *C) {
+	defer cleanEnv(c, s.store, s.do)
+	testKit := testkit.NewTestKit(c, s.store)
+	testKit.MustExec("use test")
+	testKit.MustExec("create table t (a int)")
+	testKit.MustExec("insert into t values (1)")
+
+	is := s.do.InfoSchema()
+	tbl, err := is.TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
+	c.Assert(err, IsNil)
+	tableInfo := tbl.Meta()
+	h := s.do.StatsHandle()
+
+	h.Update(is)
+	statsTbl := h.GetTableStats(tableInfo)
+	c.Assert(statistics.TableAnalyzed(statsTbl), IsFalse)
+
+	testKit.MustExec("analyze table t")
+	h.Update(is)
+	statsTbl = h.GetTableStats(tableInfo)
+	c.Assert(statistics.TableAnalyzed(statsTbl), IsTrue)
+
+	h.Clear()
+	oriLease := h.Lease
+	// set it to non-zero so we will use load by need strategy
+	h.Lease = 1
+	defer func() {
+		h.Lease = oriLease
+	}()
+	h.Update(is)
+	statsTbl = h.GetTableStats(tableInfo)
+	c.Assert(statistics.TableAnalyzed(statsTbl), IsTrue)
+}
+
 func (s *testStatsUpdateSuite) TestUpdateErrorRate(c *C) {
 	defer cleanEnv(c, s.store, s.do)
 	h := s.do.StatsHandle()