planner: support no_hash_join hint on optimizer (#45538)

planner/core/exhaust_physical_plans.go

@@ -229,7 +229,8 @@ func (p *LogicalJoin) GetMergeJoin(prop *property.PhysicalProperty, schema *expr
 	}
 	// If TiDB_SMJ hint is existed, it should consider enforce merge join,
 	// because we can't trust lhsChildProperty completely.
-	if (p.preferJoinType & preferMergeJoin) > 0 {
+	if (p.preferJoinType&preferMergeJoin) > 0 ||
+		(p.preferJoinType&preferNoHashJoin) > 0 { // if hash join is not allowed, generate as many other types of join as possible to avoid 'cant-find-plan' error.
 		joins = append(joins, p.getEnforcedMergeJoin(prop, schema, statsInfo)...)
 	}
 
@@ -387,6 +388,7 @@ func (p *LogicalJoin) getHashJoins(prop *property.PhysicalProperty) (joins []Phy
 		forceLeftToBuild = false
 		forceRightToBuild = false
 	}
+
 	joins = make([]PhysicalPlan, 0, 2)
 	switch p.JoinType {
 	case SemiJoin, AntiSemiJoin, LeftOuterSemiJoin, AntiLeftOuterSemiJoin:
@@ -433,7 +435,15 @@ func (p *LogicalJoin) getHashJoins(prop *property.PhysicalProperty) (joins []Phy
 			}
 		}
 	}
+
 	forced = (p.preferJoinType&preferHashJoin > 0) || forceLeftToBuild || forceRightToBuild
+	noHashJoin := (p.preferJoinType & preferNoHashJoin) > 0
+	if !forced && noHashJoin {
+		return nil, false
+	} else if forced && noHashJoin {
+		p.ctx.GetSessionVars().StmtCtx.AppendWarning(ErrInternal.GenWithStack(
+			"Some HASH_JOIN and NO_HASH_JOIN hints conflict, NO_HASH_JOIN is ignored"))
+	}
 	return
 }
 

planner/core/logical_plan_builder.go

@@ -95,6 +95,8 @@ const (
 	HintINLMJ = "inl_merge_join"
 	// TiDBHashJoin is hint enforce hash join.
 	TiDBHashJoin = "tidb_hj"
+	// HintNoHashJoin is the hint to enforce the query not to use hash join.
+	HintNoHashJoin = "no_hash_join"
 	// HintHJ is hint enforce hash join.
 	HintHJ = "hash_join"
 	// HintHashJoinBuild is hint enforce hash join's build side
@@ -623,6 +625,14 @@ func (p *LogicalJoin) setPreferredJoinTypeAndOrder(hintInfo *tableHintInfo) {
 		p.preferJoinType |= preferHashJoin
 		p.rightPreferJoinType |= preferHashJoin
 	}
+	if hintInfo.ifPreferNoHashJoin(lhsAlias) {
+		p.preferJoinType |= preferNoHashJoin
+		p.leftPreferJoinType |= preferNoHashJoin
+	}
+	if hintInfo.ifPreferNoHashJoin(rhsAlias) {
+		p.preferJoinType |= preferNoHashJoin
+		p.rightPreferJoinType |= preferNoHashJoin
+	}
 	if hintInfo.ifPreferINLJ(lhsAlias) {
 		p.preferJoinType |= preferLeftAsINLJInner
 		p.leftPreferJoinType |= preferINLJ
@@ -3688,6 +3698,7 @@ func (b *PlanBuilder) pushTableHints(hints []*ast.TableOptimizerHint, currentLev
 	hints = b.hintProcessor.GetCurrentStmtHints(hints, currentLevel)
 	var (
 		sortMergeTables, inljTables, inlhjTables, inlmjTables, hashJoinTables, bcTables []hintTableInfo
+		noHashJoinTables                                                                []hintTableInfo
 		shuffleJoinTables                                                               []hintTableInfo
 		indexHintList, indexMergeHintList                                               []indexHintInfo
 		tiflashTables, tikvTables                                                       []hintTableInfo
@@ -3702,7 +3713,7 @@ func (b *PlanBuilder) pushTableHints(hints []*ast.TableOptimizerHint, currentLev
 	for _, hint := range hints {
 		// Set warning for the hint that requires the table name.
 		switch hint.HintName.L {
-		case TiDBMergeJoin, HintSMJ, TiDBIndexNestedLoopJoin, HintINLJ, HintINLHJ, HintINLMJ,
+		case TiDBMergeJoin, HintSMJ, TiDBIndexNestedLoopJoin, HintINLJ, HintINLHJ, HintINLMJ, HintNoHashJoin,
 			TiDBHashJoin, HintHJ, HintUseIndex, HintIgnoreIndex, HintForceIndex, HintOrderIndex, HintNoOrderIndex, HintIndexMerge, HintLeading:
 			if len(hint.Tables) == 0 {
 				b.pushHintWithoutTableWarning(hint)
@@ -3725,6 +3736,8 @@ func (b *PlanBuilder) pushTableHints(hints []*ast.TableOptimizerHint, currentLev
 			inlmjTables = append(inlmjTables, tableNames2HintTableInfo(b.ctx, hint.HintName.L, hint.Tables, b.hintProcessor, currentLevel)...)
 		case TiDBHashJoin, HintHJ:
 			hashJoinTables = append(hashJoinTables, tableNames2HintTableInfo(b.ctx, hint.HintName.L, hint.Tables, b.hintProcessor, currentLevel)...)
+		case HintNoHashJoin:
+			noHashJoinTables = append(noHashJoinTables, tableNames2HintTableInfo(b.ctx, hint.HintName.L, hint.Tables, b.hintProcessor, currentLevel)...)
 		case HintMPP1PhaseAgg:
 			aggHints.preferAggType |= preferMPP1PhaseAgg
 		case HintMPP2PhaseAgg:
@@ -3835,6 +3848,7 @@ func (b *PlanBuilder) pushTableHints(hints []*ast.TableOptimizerHint, currentLev
 		shuffleJoinTables:         shuffleJoinTables,
 		indexNestedLoopJoinTables: indexNestedLoopJoinTables{inljTables, inlhjTables, inlmjTables},
 		hashJoinTables:            hashJoinTables,
+		noHashJoinTables:          noHashJoinTables,
 		indexHintList:             indexHintList,
 		tiflashTables:             tiflashTables,
 		tikvTables:                tikvTables,
@@ -7049,6 +7063,8 @@ func getInnerFromParenthesesAndUnaryPlus(expr ast.ExprNode) ast.ExprNode {
 // containDifferentJoinTypes checks whether `preferJoinType` contains different
 // join types.
 func containDifferentJoinTypes(preferJoinType uint) bool {
+	preferJoinType &= ^preferNoHashJoin
+
 	inlMask := preferRightAsINLJInner ^ preferLeftAsINLJInner
 	inlhjMask := preferRightAsINLHJInner ^ preferLeftAsINLHJInner
 	inlmjMask := preferRightAsINLMJInner ^ preferLeftAsINLMJInner

planner/core/logical_plans.go

@@ -117,6 +117,7 @@ const (
 	preferHJBuild
 	preferHJProbe
 	preferHashJoin
+	preferNoHashJoin
 	preferMergeJoin
 	preferBCJoin
 	preferShuffleJoin

planner/core/planbuilder.go

@@ -93,6 +93,7 @@ type tableHintInfo struct {
 	broadcastJoinTables []hintTableInfo
 	shuffleJoinTables   []hintTableInfo
 	hashJoinTables      []hintTableInfo
+	noHashJoinTables    []hintTableInfo
 	indexHintList       []indexHintInfo
 	tiflashTables       []hintTableInfo
 	tikvTables          []hintTableInfo
@@ -237,6 +238,10 @@ func (info *tableHintInfo) ifPreferHashJoin(tableNames ...*hintTableInfo) bool {
 	return info.matchTableName(tableNames, info.hashJoinTables)
 }
 
+func (info *tableHintInfo) ifPreferNoHashJoin(tableNames ...*hintTableInfo) bool {
+	return info.matchTableName(tableNames, info.noHashJoinTables)
+}
+
 func (info *tableHintInfo) ifPreferHJBuild(tableNames ...*hintTableInfo) bool {
 	return info.matchTableName(tableNames, info.hjBuildTables)
 }

planner/core/rule_join_reorder_test.go

@@ -62,6 +62,17 @@ func TestStraightJoinHint(t *testing.T) {
 	runJoinReorderTestData(t, tk, "TestStraightJoinHint")
 }
 
+func TestNoHashJoinHint(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t1(a int, b int, key(a));")
+	tk.MustExec("create table t2(a int, b int, key(a));")
+	tk.MustExec("create table t3(a int, b int, key(a));")
+	tk.MustExec("create table t4(a int, b int, key(a));")
+	runJoinReorderTestData(t, tk, "TestNoHashJoinHint")
+}
+
 func TestLeadingJoinHint(t *testing.T) {
 	store := testkit.CreateMockStore(t)