hint: avoid duplicate hints in QBHintHandler (#53921)

planner/core/casetest/testdata/integration_suite_out.json

@@ -7245,10 +7245,7 @@
           "      └─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"
         ]
       },
       {
@@ -7280,10 +7277,7 @@
           "                └─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"
         ]
       },
       {

planner/core/casetest/testdata/plan_suite_out.json

@@ -839,10 +839,7 @@
           "                      └─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;",
@@ -872,10 +869,7 @@
           "                  └─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",

planner/core/issuetest/BUILD.bazel

@@ -6,6 +6,6 @@ go_test(
     srcs = ["planner_issue_test.go"],
     flaky = True,
     race = "on",
-    shard_count = 12,
+    shard_count = 13,
     deps = ["//testkit"],
 )

planner/core/issuetest/planner_issue_test.go

@@ -277,3 +277,15 @@ func TestIssue49109(t *testing.T) {
 
 	tk.MustQuery("SELECT t0.c0 FROM v0, t0 LEFT JOIN t1 ON t0.c0 WHERE ((INET_ATON('5V')) IS NULL);").Check(testkit.Rows("0", "0", "0", "0", "<nil>", "<nil>", "<nil>", "<nil>", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "2", "2", "2", "2", "2", "2", "2", "2", "2", "2", "2", "2", "2", "2", "2", "2"))
 }
+
+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())
+}

util/hint/BUILD.bazel

@@ -15,6 +15,7 @@ go_library(
         "//util/dbterror",
         "//util/logutil",
         "@com_github_pingcap_errors//:errors",
+        "@org_golang_x_exp//slices",
         "@org_uber_go_zap//:zap",
     ],
 )

util/hint/hint_processor.go

@@ -29,6 +29,7 @@ import (
 	"github.com/pingcap/tidb/util/dbterror"
 	"github.com/pingcap/tidb/util/logutil"
 	"go.uber.org/zap"
+	"golang.org/x/exp/slices"
 )
 
 var supportedHintNameForInsertStmt = map[string]struct{}{}
@@ -615,7 +616,9 @@ func (p *BlockHintProcessor) GetCurrentStmtHints(hints []*ast.TableOptimizerHint
 			}
 			continue
 		}
-		p.QbHints[offset] = append(p.QbHints[offset], hint)
+		if !slices.Contains(p.QbHints[offset], hint) {
+			p.QbHints[offset] = append(p.QbHints[offset], hint)
+		}
 	}
 	return p.QbHints[currentOffset]
 }