hint: avoid duplicate hints in QBHintHandler (#53921)

close #53767

pkg/planner/core/casetest/hint/BUILD.bazel

@@ -9,7 +9,7 @@ go_test(
     ],
     data = glob(["testdata/**"]),
     flaky = True,
-    shard_count = 7,
+    shard_count = 8,
     deps = [
         "//pkg/config",
         "//pkg/domain",

pkg/planner/core/casetest/hint/hint_test.go

@@ -372,3 +372,15 @@ func TestHints(t *testing.T) {
 		tk.MustQuery("show warnings").Check(testkit.Rows(output[i].Warn...))
 	}
 }
+
+func TestQBHintHandlerDuplicateObjects(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("CREATE TABLE t_employees  (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, fname VARCHAR(25) NOT NULL, lname VARCHAR(25) NOT NULL, store_id INT NOT NULL, department_id INT NOT NULL);")
+	tk.MustExec("ALTER TABLE t_employees ADD INDEX idx(department_id);")
+
+	// Explain statement
+	tk.MustQuery("EXPLAIN WITH t AS (SELECT /*+ inl_join(e) */ em.* FROM t_employees em JOIN t_employees e WHERE em.store_id = e.department_id) SELECT * FROM t;")
+	tk.MustQuery("show warnings").Check(testkit.Rows())
+}

pkg/planner/core/casetest/hint/testdata/integration_suite_out.json

@@ -1449,10 +1449,7 @@
           "      └─IndexRangeScan_148 19492.21 cop[tikv] table:t1, index:idx_a(a) range: decided by [eq(test.t1.a, test.t1.a)], keep order:false, stats:pseudo"
         ],
         "Warn": [
-          "[planner:1815]We can only use one leading hint at most, when multiple leading hints are used, all leading hints will be invalid",
-          "[planner:1815]There are no matching table names for (t1) in optimizer hint /*+ INL_JOIN(t1, t1) */ or /*+ TIDB_INLJ(t1, t1) */. Maybe you can use the table alias name",
-          "[planner:1815]We can only use one leading hint at most, when multiple leading hints are used, all leading hints will be invalid",
-          "[planner:1815]There are no matching table names for (t1, t1) in optimizer hint /*+ INL_JOIN(t1, t1, t1) */ or /*+ TIDB_INLJ(t1, t1, t1) */. Maybe you can use the table alias name"
+          "[planner:1815]We can only use one leading hint at most, when multiple leading hints are used, all leading hints will be invalid"
         ]
       },
       {
@@ -1484,10 +1481,7 @@
           "                └─TableRowIDScan_69 9990.00 cop[tikv] table:t2 keep order:false, stats:pseudo"
         ],
         "Warn": [
-          "[planner:1815]We can only use one leading hint at most, when multiple leading hints are used, all leading hints will be invalid",
-          "[planner:1815]There are no matching table names for (t2) in optimizer hint /*+ MERGE_JOIN(t2, t2) */ or /*+ TIDB_SMJ(t2, t2) */. Maybe you can use the table alias name",
-          "[planner:1815]We can only use one leading hint at most, when multiple leading hints are used, all leading hints will be invalid",
-          "[planner:1815]There are no matching table names for (t2, t2) in optimizer hint /*+ MERGE_JOIN(t2, t2, t2) */ or /*+ TIDB_SMJ(t2, t2, t2) */. Maybe you can use the table alias name"
+          "[planner:1815]We can only use one leading hint at most, when multiple leading hints are used, all leading hints will be invalid"
         ]
       },
       {

pkg/planner/core/casetest/physicalplantest/testdata/plan_suite_out.json

@@ -835,10 +835,7 @@
           "                      └─Selection 9990.00 mpp[tiflash]  not(isnull(test.t.a))",
           "                        └─TableFullScan 10000.00 mpp[tiflash] table:t1 pushed down filter:empty, keep order:false, stats:pseudo"
         ],
-        "Warn": [
-          "[planner:1815]There are no matching table names for (t1, t) in optimizer hint /*+ SHUFFLE_JOIN(t1, t, t1, t) */ or /*+ SHUFFLE_JOIN(t1, t, t1, t) */. Maybe you can use the table alias name",
-          "[planner:1815]There are no matching table names for (t1, t, t1, t) in optimizer hint /*+ SHUFFLE_JOIN(t1, t, t1, t, t1, t) */ or /*+ SHUFFLE_JOIN(t1, t, t1, t, t1, t) */. Maybe you can use the table alias name"
-        ]
+        "Warn": null
       },
       {
         "SQL": "WITH CTE AS (SELECT /*+ MERGE(), broadcast_join(t1, t) */ t.a, t.b FROM t join t t1 where t.a = t1.a) SELECT * FROM CTE WHERE CTE.a <18 union select * from cte where cte.b > 1;",
@@ -868,10 +865,7 @@
           "                  └─Selection(Probe) 9990.00 mpp[tiflash]  not(isnull(test.t.a))",
           "                    └─TableFullScan 10000.00 mpp[tiflash] table:t1 pushed down filter:empty, keep order:false, stats:pseudo"
         ],
-        "Warn": [
-          "[planner:1815]There are no matching table names for (t1, t) in optimizer hint /*+ BROADCAST_JOIN(t1, t, t1, t) */ or /*+ TIDB_BCJ(t1, t, t1, t) */. Maybe you can use the table alias name",
-          "[planner:1815]There are no matching table names for (t1, t, t1, t) in optimizer hint /*+ BROADCAST_JOIN(t1, t, t1, t, t1, t) */ or /*+ TIDB_BCJ(t1, t, t1, t, t1, t) */. Maybe you can use the table alias name"
-        ]
+        "Warn": null
       },
       {
         "SQL": "select /*+ read_from_storage(tiflash[t1, t2]), broadcast_join(t1, t2), hash_join_build(t2) */ * from t t1 left join t t2 on t1.a=t2.a",

pkg/util/hint/hint_query_block.go

@@ -16,6 +16,7 @@ package hint
 
 import (
 	"fmt"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -295,7 +296,9 @@ func (p *QBHintHandler) GetCurrentStmtHints(hints []*ast.TableOptimizerHint, cur
 			}
 			continue
 		}
-		p.QBOffsetToHints[offset] = append(p.QBOffsetToHints[offset], hint)
+		if !slices.Contains(p.QBOffsetToHints[offset], hint) {
+			p.QBOffsetToHints[offset] = append(p.QBOffsetToHints[offset], hint)
+		}
 	}
 	return p.QBOffsetToHints[currentOffset]
 }

tests/integrationtest/r/index_merge.result

@@ -852,7 +852,6 @@ show warnings;
 Level	Code	Message
 Warning	1815	use_index_merge(index_merge.t_alias) is inapplicable, check whether the table(index_merge.t_alias) exists
 Warning	1815	use_index_merge(index_merge.t_alias) is inapplicable, check whether the table(index_merge.t_alias) exists
-Warning	1815	use_index_merge(index_merge.t_alias) is inapplicable, check whether the table(index_merge.t_alias) exists
 with recursive cte1 as (select 1 c1, 1 c2, 1 c3 UNION ALL select /*+ use_index_merge(t_alias) */ c1 + 1, c2 + 1, c3 + 1 from cte1 t_alias where c1 < 10 or c2 < 10 and c3 < 10) select * from cte1 order by 1;
 c1	c2	c3
 1	1	1