statistics: improve out-of-range estimation strategy

planner/core/testdata/analyze_suite_out.json

@@ -60,8 +60,8 @@
         "SQL": "explain format = 'brief' select * from t where a <= 5 and b <= 5",
         "RatioOfPseudoEstimate": 10,
         "Plan": [
-          "TableReader 29.77 root  data:Selection",
-          "└─Selection 29.77 cop[tikv]  le(test.t.a, 5), le(test.t.b, 5)",
+          "TableReader 28.80 root  data:Selection",
+          "└─Selection 28.80 cop[tikv]  le(test.t.a, 5), le(test.t.b, 5)",
           "  └─TableFullScan 80.00 cop[tikv] table:t keep order:false"
         ]
       },
@@ -454,18 +454,18 @@
       {
         "SQL": "explain format = 'brief' select * from t where a = 7639902",
         "Plan": [
-          "IndexReader 6.68 root  index:IndexRangeScan",
-          "└─IndexRangeScan 6.68 cop[tikv] table:t, index:PRIMARY(a, c, b) range:[7639902,7639902], keep order:false"
+          "IndexReader 5.95 root  index:IndexRangeScan",
+          "└─IndexRangeScan 5.95 cop[tikv] table:t, index:PRIMARY(a, c, b) range:[7639902,7639902], keep order:false"
         ]
       },
       {
         "SQL": "explain format = 'brief' select c, b from t where a = 7639902 order by b asc limit 6",
         "Plan": [
-          "Projection 6.00 root  test.t.c, test.t.b",
-          "└─TopN 6.00 root  test.t.b, offset:0, count:6",
-          "  └─IndexReader 6.00 root  index:TopN",
-          "    └─TopN 6.00 cop[tikv]  test.t.b, offset:0, count:6",
-          "      └─IndexRangeScan 6.68 cop[tikv] table:t, index:PRIMARY(a, c, b) range:[7639902,7639902], keep order:false"
+          "Projection 5.95 root  test.t.c, test.t.b",
+          "└─TopN 5.95 root  test.t.b, offset:0, count:6",
+          "  └─IndexReader 5.95 root  index:TopN",
+          "    └─TopN 5.95 cop[tikv]  test.t.b, offset:0, count:6",
+          "      └─IndexRangeScan 5.95 cop[tikv] table:t, index:PRIMARY(a, c, b) range:[7639902,7639902], keep order:false"
         ]
       }
     ]

statistics/cmsketch.go

@@ -530,14 +530,6 @@ func (c *TopN) Num() int {
 	return len(c.TopN)
 }
 
-// outOfRange checks whether the the given value falls back in [TopN.LowestOne, TopN.HighestOne].
-func (c *TopN) outOfRange(val []byte) bool {
-	if c == nil || len(c.TopN) == 0 {
-		return true
-	}
-	return bytes.Compare(c.TopN[0].Encoded, val) > 0 || bytes.Compare(val, c.TopN[c.Num()-1].Encoded) > 0
-}
-
 // DecodedString returns the value with decoded result.
 func (c *TopN) DecodedString(ctx sessionctx.Context, colTypes []byte) (string, error) {
 	builder := &strings.Builder{}
@@ -775,7 +767,7 @@ func MergePartTopN2GlobalTopN(sc *stmtctx.StatementContext, version int, topNs [
 					datum = d
 				}
 				// Get the row count which the value is equal to the encodedVal from histogram.
-				count := hists[j].equalRowCount(datum, isIndex)
+				count, _ := hists[j].equalRowCount(datum, isIndex)
 				if count != 0 {
 					counter[encodedVal] += count
 					// Remove the value corresponding to encodedVal from the histogram.

statistics/handle/update.go

@@ -1254,12 +1254,10 @@ func (h *Handle) RecalculateExpectCount(q *statistics.QueryFeedback) error {
 	expected := 0.0
 	if isIndex {
 		idx := t.Indices[id]
-		expected, err = idx.GetRowCount(sc, nil, ranges, t.ModifyCount)
-		expected *= idx.GetIncreaseFactor(t.Count)
+		expected, err = idx.GetRowCount(sc, nil, ranges, t.Count)
 	} else {
 		c := t.Columns[id]
-		expected, err = c.GetColumnRowCount(sc, ranges, t.ModifyCount, true)
-		expected *= c.GetIncreaseFactor(t.Count)
+		expected, err = c.GetColumnRowCount(sc, ranges, t.Count, true)
 	}
 	q.Expected = int64(expected)
 	return err

statistics/handle/update_test.go

@@ -1815,8 +1815,8 @@ func (s *testStatsSuite) TestAbnormalIndexFeedback(c *C) {
 			sql: "select * from t where a = 2 and b > 10",
 			hist: "column:2 ndv:20 totColSize:20\n" +
 				"num: 5 lower_bound: -9223372036854775808 upper_bound: 7 repeats: 0 ndv: 0\n" +
-				"num: 4 lower_bound: 7 upper_bound: 14 repeats: 0 ndv: 0\n" +
-				"num: 5 lower_bound: 14 upper_bound: 9223372036854775807 repeats: 0 ndv: 0",
+				"num: 6 lower_bound: 7 upper_bound: 14 repeats: 0 ndv: 0\n" +
+				"num: 8 lower_bound: 14 upper_bound: 9223372036854775807 repeats: 0 ndv: 0",
 			rangeID: tblInfo.Columns[1].ID,
 			idxID:   tblInfo.Indices[0].ID,
 			eqCount: 3,