planner: fix a bug for chunk cost model. (#14144)

pingcap · Dec 22, 2019 · 510c36d · 510c36d
1 parent c7c7b73
commit 510c36d
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Showing 3 changed files with 24 additions and 5 deletions.
diff --git a/expression/integration_test.go b/expression/integration_test.go
@@ -4743,9 +4743,9 @@ from
     (select * from t1) a
 left join
     (select bussid,date(from_unixtime(ct)) date8 from t2) b
-on 
+on
     a.period_id = b.bussid
-where 
+where
     datediff(b.date8, date(from_unixtime(a.starttime))) >= 0`
 	tk.MustQuery(q)
 }
@@ -5230,3 +5230,12 @@ func (s *testIntegrationSuite) TestCastStrToInt(c *C) {
 		c.Assert(terror.ErrorEqual(tk.Se.GetSessionVars().StmtCtx.GetWarnings()[0].Err, types.ErrTruncatedWrongVal), IsTrue)
 	}
 }
+
+func (s *testIntegrationSuite) TestIssue14146(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("create table tt(a varchar(10))")
+	tk.MustExec("insert into tt values(NULL)")
+	tk.MustExec("analyze table tt;")
+	tk.MustQuery("select * from tt").Check(testkit.Rows("<nil>"))
+}
diff --git a/statistics/handle/handle_test.go b/statistics/handle/handle_test.go
@@ -201,8 +201,8 @@ func (s *testStatsSuite) TestAvgColLen(c *C) {
 	defer cleanEnv(c, s.store, s.do)
 	testKit := testkit.NewTestKit(c, s.store)
 	testKit.MustExec("use test")
-	testKit.MustExec("create table t (c1 int, c2 varchar(100), c3 float, c4 datetime)")
-	testKit.MustExec("insert into t values(1, '1234567', 12.3, '2018-03-07 19:00:57')")
+	testKit.MustExec("create table t (c1 int, c2 varchar(100), c3 float, c4 datetime, c5 varchar(100))")
+	testKit.MustExec("insert into t values(1, '1234567', 12.3, '2018-03-07 19:00:57', NULL)")
 	testKit.MustExec("analyze table t")
 	do := s.do
 	is := do.InfoSchema()
@@ -224,7 +224,9 @@ func (s *testStatsSuite) TestAvgColLen(c *C) {
 	c.Assert(statsTbl.Columns[tableInfo.Columns[1].ID].AvgColSizeChunkFormat(statsTbl.Count), Equals, 8.0-3+8)
 	c.Assert(statsTbl.Columns[tableInfo.Columns[2].ID].AvgColSizeChunkFormat(statsTbl.Count), Equals, float64(unsafe.Sizeof(float32(12.3))))
 	c.Assert(statsTbl.Columns[tableInfo.Columns[3].ID].AvgColSizeChunkFormat(statsTbl.Count), Equals, float64(unsafe.Sizeof(types.Time{})))
-	testKit.MustExec("insert into t values(132, '123456789112', 1232.3, '2018-03-07 19:17:29')")
+	c.Assert(statsTbl.Columns[tableInfo.Columns[4].ID].AvgColSizeChunkFormat(statsTbl.Count), Equals, 8.0)
+	c.Assert(statsTbl.Columns[tableInfo.Columns[4].ID].AvgColSizeListInDisk(statsTbl.Count), Equals, 0.0)
+	testKit.MustExec("insert into t values(132, '123456789112', 1232.3, '2018-03-07 19:17:29', NULL)")
 	testKit.MustExec("analyze table t")
 	statsTbl = do.StatsHandle().GetTableStats(tableInfo)
 	c.Assert(statsTbl.Columns[tableInfo.Columns[0].ID].AvgColSize(statsTbl.Count, false), Equals, 1.5)
@@ -239,6 +241,8 @@ func (s *testStatsSuite) TestAvgColLen(c *C) {
 	c.Assert(statsTbl.Columns[tableInfo.Columns[1].ID].AvgColSizeChunkFormat(statsTbl.Count), Equals, math.Round((10.5-math.Log2(10.5))*100)/100+8)
 	c.Assert(statsTbl.Columns[tableInfo.Columns[2].ID].AvgColSizeChunkFormat(statsTbl.Count), Equals, float64(unsafe.Sizeof(float32(12.3))))
 	c.Assert(statsTbl.Columns[tableInfo.Columns[3].ID].AvgColSizeChunkFormat(statsTbl.Count), Equals, float64(unsafe.Sizeof(types.Time{})))
+	c.Assert(statsTbl.Columns[tableInfo.Columns[4].ID].AvgColSizeChunkFormat(statsTbl.Count), Equals, 8.0)
+	c.Assert(statsTbl.Columns[tableInfo.Columns[4].ID].AvgColSizeListInDisk(statsTbl.Count), Equals, 0.0)
 }
 
 func (s *testStatsSuite) TestDurationToTS(c *C) {

diff --git a/statistics/histogram.go b/statistics/histogram.go
@@ -155,6 +155,9 @@ func (c *Column) AvgColSizeChunkFormat(count int64) float64 {
 	// Add 8 bytes for unfixed-len type's offsets.
 	// Minus Log2(avgSize) for unfixed-len type LEN.
 	avgSize := float64(c.TotColSize) / float64(count)
+	if avgSize < 1 {
+		return math.Round(avgSize*100)/100 + 8
+	}
 	return math.Round((avgSize-math.Log2(avgSize))*100)/100 + 8
 }
 
@@ -176,6 +179,9 @@ func (c *Column) AvgColSizeListInDisk(count int64) float64 {
 	// Keep two decimal place.
 	// Minus Log2(avgSize) for unfixed-len type LEN.
 	avgSize := float64(c.TotColSize) / float64(count)
+	if avgSize < 1 {
+		return math.Round((avgSize)*100) / 100
+	}
 	return math.Round((avgSize-math.Log2(avgSize))*100) / 100
 }