planner: fix count(*) return wrong value for information_schema.tables (#57506)

close #56987

Author: joechenrh

pkg/executor/infoschema_reader_test.go

@@ -552,6 +552,15 @@ func TestTablesTable(t *testing.T) {
 		testkit.Rows())
 	tk.MustQuery(fmt.Sprintf("select table_schema, table_name, tidb_table_id from information_schema.tables where table_schema = 'db1' and table_name = 't1' and tidb_table_id in (%s,%s)", tableMetas[0].id, tableMetas[1].id)).Check(
 		testkit.Rows(toString(tableMetas[0])))
+
+	selectTables, err := strconv.Atoi(tk.MustQuery("select count(*) from information_schema.tables where upper(table_name) = 'T1'").Rows()[0][0].(string))
+	require.NoError(t, err)
+	totalTables, err := strconv.Atoi(tk.MustQuery("select count(*) from information_schema.tables").Rows()[0][0].(string))
+	require.NoError(t, err)
+	remainTables, err := strconv.Atoi(tk.MustQuery("select count(*) from information_schema.tables where upper(table_name) != 'T1'").Rows()[0][0].(string))
+	require.NoError(t, err)
+	require.Equal(t, 2, selectTables)
+	require.Equal(t, totalTables, remainTables+selectTables)
 }
 
 func TestColumnTable(t *testing.T) {

pkg/planner/core/memtable_infoschema_extractor.go

@@ -260,8 +260,17 @@ func (e *InfoSchemaBaseExtractor) filter(colName string, val string) bool {
 			return true
 		}
 	}
+
+	toLower := false
+	if e.extractLowerString != nil {
+		toLower = e.extractLowerString[colName]
+	}
+
 	predVals, ok := e.ColPredicates[colName]
 	if ok && len(predVals) > 0 {
+		if toLower {
+			return !predVals.Exist(strings.ToLower(val))
+		}
 		fn, ok := e.pushedDownFuncs[colName]
 		if ok {
 			return !predVals.Exist(fn(val))

pkg/planner/core/memtable_predicate_extractor.go

@@ -51,6 +51,9 @@ import (
 type extractHelper struct {
 	enableScalarPushDown bool
 	pushedDownFuncs      map[string]func(string) string
+
+	// Store whether the extracted strings for a specific column are converted to lower case
+	extractLowerString map[string]bool
 }
 
 func (extractHelper) extractColInConsExpr(ctx base.PlanContext, extractCols map[int64]*types.FieldName, expr *expression.ScalarFunction) (string, []types.Datum) {
@@ -342,6 +345,11 @@ func (helper *extractHelper) extractCol(
 			break
 		}
 	}
+
+	if helper.extractLowerString == nil {
+		helper.extractLowerString = make(map[string]bool)
+	}
+	helper.extractLowerString[extractColName] = valueToLower
 	return
 }