This is an automated cherry-pick of pingcap#50277

Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>

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

@@ -9,7 +9,7 @@ go_test(
     ],
     data = glob(["testdata/**"]),
     flaky = True,
-    shard_count = 6,
+    shard_count = 7,
     deps = [
         "//pkg/config",
         "//pkg/domain",

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

@@ -340,3 +340,29 @@ func TestOptimizeHintOnPartitionTable(t *testing.T) {
 	tk.MustQuery("SELECT /*+ MAX_EXECUTION_TIME(10), dtc(name=tt) unknow(t1,t2) */ SLEEP(5)").Check(testkit.Rows("0"))
 	require.Len(t, tk.Session().GetSessionVars().StmtCtx.GetWarnings(), 2)
 }
+
+func TestHints(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t1 (a int);")
+	tk.MustExec("create table t2 (a int);")
+	tk.MustExec("create table t3 (a int);")
+	var input []string
+	var output []struct {
+		SQL  string
+		Plan []string
+		Warn []string
+	}
+	integrationSuiteData := GetIntegrationSuiteData()
+	integrationSuiteData.LoadTestCases(t, &input, &output)
+	for i, tt := range input {
+		testdata.OnRecord(func() {
+			output[i].SQL = tt
+			output[i].Plan = testdata.ConvertRowsToStrings(tk.MustQuery("explain format = 'brief' " + tt).Rows())
+			output[i].Warn = testdata.ConvertRowsToStrings(tk.MustQuery("show warnings").Rows())
+		})
+		tk.MustQuery("explain format = 'brief' " + tt).Check(testkit.Rows(output[i].Plan...))
+		tk.MustQuery("show warnings").Check(testkit.Rows(output[i].Warn...))
+	}
+}

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

@@ -180,5 +180,11 @@
       "explain format = 'brief' select /*+ use_index(t, idx)*/ * from t",
       "explain format = 'brief' select /*+ use_index(t)*/ * from t"
     ]
+  },
+  {
+    "name": "TestHints",
+    "cases": [
+      "select * from t1, t2, t3 union all select /*+ leading(t3, t2) */ * from t1, t2, t3 union all select * from t1, t2, t3"
+    ]
   }
 ]

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

@@ -325,7 +325,7 @@
           "        └─TableFullScan 10000.00 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]leading hint is inapplicable, check if the leading hint table is valid"
         ]
       },
       {
@@ -347,7 +347,7 @@
           "        └─TableFullScan 10000.00 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]leading hint is inapplicable, check if the leading hint table is valid"
         ]
       },
       {
@@ -1862,5 +1862,44 @@
         "Warn": null
       }
     ]
+  },
+  {
+    "Name": "TestHints",
+    "Cases": [
+      {
+        "SQL": "select * from t1, t2, t3 union all select /*+ leading(t3, t2) */ * from t1, t2, t3 union all select * from t1, t2, t3",
+        "Plan": [
+          "Union 3000000000000.00 root  ",
+          "├─HashJoin 1000000000000.00 root  CARTESIAN inner join",
+          "│ ├─TableReader(Build) 10000.00 root  data:TableFullScan",
+          "│ │ └─TableFullScan 10000.00 cop[tikv] table:t3 keep order:false, stats:pseudo",
+          "│ └─HashJoin(Probe) 100000000.00 root  CARTESIAN inner join",
+          "│   ├─TableReader(Build) 10000.00 root  data:TableFullScan",
+          "│   │ └─TableFullScan 10000.00 cop[tikv] table:t2 keep order:false, stats:pseudo",
+          "│   └─TableReader(Probe) 10000.00 root  data:TableFullScan",
+          "│     └─TableFullScan 10000.00 cop[tikv] table:t1 keep order:false, stats:pseudo",
+          "├─Projection 1000000000000.00 root  test.t1.a->Column#19, test.t2.a->Column#20, test.t3.a->Column#21",
+          "│ └─HashJoin 1000000000000.00 root  CARTESIAN inner join",
+          "│   ├─TableReader(Build) 10000.00 root  data:TableFullScan",
+          "│   │ └─TableFullScan 10000.00 cop[tikv] table:t1 keep order:false, stats:pseudo",
+          "│   └─HashJoin(Probe) 100000000.00 root  CARTESIAN inner join",
+          "│     ├─TableReader(Build) 10000.00 root  data:TableFullScan",
+          "│     │ └─TableFullScan 10000.00 cop[tikv] table:t2 keep order:false, stats:pseudo",
+          "│     └─TableReader(Probe) 10000.00 root  data:TableFullScan",
+          "│       └─TableFullScan 10000.00 cop[tikv] table:t3 keep order:false, stats:pseudo",
+          "└─HashJoin 1000000000000.00 root  CARTESIAN inner join",
+          "  ├─TableReader(Build) 10000.00 root  data:TableFullScan",
+          "  │ └─TableFullScan 10000.00 cop[tikv] table:t3 keep order:false, stats:pseudo",
+          "  └─HashJoin(Probe) 100000000.00 root  CARTESIAN inner join",
+          "    ├─TableReader(Build) 10000.00 root  data:TableFullScan",
+          "    │ └─TableFullScan 10000.00 cop[tikv] table:t2 keep order:false, stats:pseudo",
+          "    └─TableReader(Probe) 10000.00 root  data:TableFullScan",
+          "      └─TableFullScan 10000.00 cop[tikv] table:t1 keep order:false, stats:pseudo"
+        ],
+        "Warn": [
+          "Warning 1815 leading hint is inapplicable, check if the leading hint table has join conditions with other tables"
+        ]
+      }
+    ]
   }
 ]

pkg/planner/core/logical_plan_builder.go

@@ -4199,6 +4199,7 @@ func (b *PlanBuilder) pushTableHints(hints []*ast.TableOptimizerHint, currentLev
 			b.ctx.GetSessionVars().StmtCtx.AppendWarning(ErrInternal.GenWithStack("We can only use the straight_join hint, when we use the leading hint and straight_join hint at the same time, all leading hints will be invalid"))
 		}
 	}
+<<<<<<< HEAD
 	b.tableHintInfo = append(b.tableHintInfo, tableHintInfo{
 		sortMergeJoinTables:       sortMergeTables,
 		broadcastJoinTables:       bcTables,
@@ -4215,6 +4216,24 @@ func (b *PlanBuilder) pushTableHints(hints []*ast.TableOptimizerHint, currentLev
 		indexMergeHintList:        indexMergeHintList,
 		timeRangeHint:             timeRangeHint,
 		limitHints:                limitHints,
+=======
+	b.tableHintInfo = append(b.tableHintInfo, &h.TableHintInfo{
+		SortMergeJoinTables:       sortMergeTables,
+		BroadcastJoinTables:       bcTables,
+		ShuffleJoinTables:         shuffleJoinTables,
+		IndexNestedLoopJoinTables: h.IndexNestedLoopJoinTables{INLJTables: inljTables, INLHJTables: inlhjTables, INLMJTables: inlmjTables},
+		NoIndexJoinTables:         h.IndexNestedLoopJoinTables{INLJTables: noIndexJoinTables, INLHJTables: noIndexHashJoinTables, INLMJTables: noIndexMergeJoinTables},
+		HashJoinTables:            hashJoinTables,
+		NoHashJoinTables:          noHashJoinTables,
+		NoMergeJoinTables:         noMergeJoinTables,
+		IndexHintList:             indexHintList,
+		TiFlashTables:             tiflashTables,
+		TiKVTables:                tikvTables,
+		AggHints:                  aggHints,
+		IndexMergeHintList:        indexMergeHintList,
+		TimeRangeHint:             timeRangeHint,
+		LimitHints:                limitHints,
+>>>>>>> 0236944eab4 (planner: fix leading hint cannot take effect in UNION ALL statements (#50277))
 		MergeHints:                MergeHints,
 		leadingJoinOrder:          leadingJoinOrder,
 		hjBuildTables:             hjBuildTables,
@@ -4298,7 +4317,7 @@ func (b *PlanBuilder) TableHints() *tableHintInfo {
 	if len(b.tableHintInfo) == 0 {
 		return nil
 	}
-	return &(b.tableHintInfo[len(b.tableHintInfo)-1])
+	return b.tableHintInfo[len(b.tableHintInfo)-1]
 }
 
 func (b *PlanBuilder) buildSelect(ctx context.Context, sel *ast.SelectStmt) (p LogicalPlan, err error) {

pkg/planner/core/planbuilder.go

@@ -533,7 +533,11 @@ type PlanBuilder struct {
 	colMapper map[*ast.ColumnNameExpr]int
 	// visitInfo is used for privilege check.
 	visitInfo     []visitInfo
+<<<<<<< HEAD
 	tableHintInfo []tableHintInfo
+=======
+	tableHintInfo []*hint.TableHintInfo
+>>>>>>> 0236944eab4 (planner: fix leading hint cannot take effect in UNION ALL statements (#50277))
 	// optFlag indicates the flags of the optimizer rules.
 	optFlag uint64
 	// capFlag indicates the capability flags.

pkg/planner/core/rule_join_reorder_greedy.go

@@ -79,7 +79,14 @@ func (s *joinReorderGreedySolver) solve(joinNodePlans []LogicalPlan, tracer *joi
 			// Getting here means that there is no join condition between the table used in the leading hint and other tables
 			// For example: select /*+ leading(t3) */ * from t1 join t2 on t1.a=t2.a cross join t3
 			// We can not let table t3 join first.
+<<<<<<< HEAD
 			s.ctx.GetSessionVars().StmtCtx.AppendWarning(ErrInternal.GenWithStack("leading hint is inapplicable, check if the leading hint table has join conditions with other tables"))
+=======
+			// TODO(hawkingrei): we find the problem in the TestHint.
+			// 	`select * from t1, t2, t3 union all select /*+ leading(t3, t2) */ * from t1, t2, t3 union all select * from t1, t2, t3`
+			//  this sql should not return the warning. but It will not affect the result. so we will fix it as soon as possible.
+			s.ctx.GetSessionVars().StmtCtx.AppendWarning(ErrInternal.FastGen("leading hint is inapplicable, check if the leading hint table has join conditions with other tables"))
+>>>>>>> 0236944eab4 (planner: fix leading hint cannot take effect in UNION ALL statements (#50277))
 		}
 		cartesianGroup = append(cartesianGroup, newNode.p)
 	}