planner: fix an unexpected result of the inlineprojection of TopN

pkg/planner/core/operator/logicalop/logical_top_n.go

@@ -83,7 +83,8 @@ func (lt *LogicalTopN) PruneColumns(parentUsedCols []*expression.Column, opt *op
 	child := lt.Children()[0]
 	var cols []*expression.Column
 
-	lt.InlineProjection(parentUsedCols, opt)
+	snapParentUsedCols := make([]*expression.Column, 0, len(parentUsedCols))
+	snapParentUsedCols = append(snapParentUsedCols, parentUsedCols...)
 
 	lt.ByItems, cols = pruneByItems(lt, lt.ByItems, opt)
 	parentUsedCols = append(parentUsedCols, cols...)
@@ -92,6 +93,15 @@ func (lt *LogicalTopN) PruneColumns(parentUsedCols []*expression.Column, opt *op
 	if err != nil {
 		return nil, err
 	}
+	// If the length of parentUsedCols is 0, it means that the parent plan does not need this plan to output related
+	// results, such as: select count(*) from t
+	// So we set the schema of topN to 0. After inlineprojection, the schema of topN will be set to the shortest column
+	// in its child plan, and this column will not be used later.
+	if len(snapParentUsedCols) == 0 {
+		lt.SetSchema(nil)
+	}
+	lt.InlineProjection(snapParentUsedCols, opt)
+
 	return lt, nil
 }
 

pkg/planner/core/operator/logicalop/logicalop_test/BUILD.bazel

@@ -6,9 +6,10 @@ go_test(
     srcs = [
         "hash64_equals_test.go",
         "logical_mem_table_predicate_extractor_test.go",
+        "plan_execute_test.go",
     ],
     flaky = True,
-    shard_count = 33,
+    shard_count = 34,
     deps = [
         "//pkg/domain",
         "//pkg/expression",

pkg/planner/core/operator/logicalop/logicalop_test/plan_execute_test.go

@@ -0,0 +1,84 @@
+// Copyright 2019 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logicalop_test
+
+import (
+	"testing"
+
+	"github.com/pingcap/tidb/pkg/testkit"
+)
+
+func TestIssue58743(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+
+	tk := testkit.NewTestKit(t, store)
+
+	tk.MustExec("use test")
+	tk.MustExec(`
+		CREATE TABLE tlf5d55361 (
+			col_9 time NOT NULL,
+			col_10 float NOT NULL,
+			col_11 json NOT NULL,
+			col_12 date NOT NULL,
+			col_13 json NOT NULL,
+			col_14 tinyint NOT NULL,
+			col_15 date DEFAULT NULL,
+			col_16 tinyblob NOT NULL,
+			col_17 time DEFAULT '03:51:26',
+			PRIMARY KEY (col_14, col_9, col_10) /*T![clustered_index] CLUSTERED */
+		) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_general_ci
+		PARTITION BY RANGE (col_14)
+		(
+			PARTITION p0 VALUES LESS THAN (-128),
+			PARTITION p1 VALUES LESS THAN (-84),
+			PARTITION p2 VALUES LESS THAN (-41),
+			PARTITION p3 VALUES LESS THAN (-30)
+		);
+	`)
+	tk.MustExec(`
+		CREATE TABLE td8d55878 (
+			col_26 datetime DEFAULT NULL,
+			col_27 time DEFAULT NULL,
+			col_28 json DEFAULT NULL,
+			col_29 char(186) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT '4-BJKi',
+			col_30 date NOT NULL DEFAULT '1998-07-28',
+			col_31 datetime NOT NULL
+		) ENGINE=InnoDB DEFAULT CHARSET=gbk COLLATE=gbk_chinese_ci;
+	`)
+
+	tk.MustQuery(`
+		WITH cte_3 (col_128) AS (
+			SELECT /*+ USE_INDEX_MERGE(td8d55878 tlf5d55361)*/ 
+			MIN(td8d55878.col_26) AS r0
+			FROM tlf5d55361
+			JOIN td8d55878
+			GROUP BY tlf5d55361.col_17
+			HAVING tlf5d55361.col_17 <= '20:22:14.00' OR tlf5d55361.col_17 BETWEEN '21:56:23.00' AND '19:42:43.00'
+			ORDER BY r0
+			LIMIT 772780933
+		),
+		cte_4 (col_129) AS (
+			SELECT /*+ HASH_AGG()*/ 
+			SUM(tlf5d55361.col_14) AS r0
+			FROM td8d55878
+			JOIN tlf5d55361 ON tlf5d55361.col_17 = td8d55878.col_27
+			GROUP BY td8d55878.col_30
+			HAVING ISNULL(td8d55878.col_30) OR td8d55878.col_30 BETWEEN '2009-09-08' AND '1980-11-17'
+		)
+		SELECT SUM((cte_4.col_129 IN (0.65, 564617.3335, 45, 0.319, 0.4427)) IS TRUE)
+		FROM cte_4
+		JOIN cte_3;
+	`).Equal(nil)
+}