Gen4: Keep track of left and right predicates in outer joins

go/test/endtoend/vtgate/misc_test.go

@@ -753,6 +753,24 @@ func TestSimpleOrderBy(t *testing.T) {
 	assertMatches(t, conn, `SELECT id2 FROM t1 ORDER BY id2 ASC`, `[[INT64(5)] [INT64(6)] [INT64(7)] [INT64(8)] [INT64(9)] [INT64(10)]]`)
 }
 
+func TestSelectEqualUniqueOuterJoinRightPredicate(t *testing.T) {
+	defer cluster.PanicHandler(t)
+	ctx := context.Background()
+	conn, err := mysql.Connect(ctx, &vtParams)
+	require.NoError(t, err)
+	defer conn.Close()
+
+	exec(t, conn, `delete from t1`)
+	exec(t, conn, `delete from t2`)
+	defer func() {
+		exec(t, conn, `delete from t1`)
+		exec(t, conn, `delete from t2`)
+	}()
+	exec(t, conn, "insert into t1(id1, id2) values (0,10),(1,9),(2,8),(3,7),(4,6),(5,5)")
+	exec(t, conn, "insert into t2(id3, id4) values (0,20),(1,19),(2,18),(3,17),(4,16),(5,15)")
+	assertMatches(t, conn, `SELECT id3 FROM t1 LEFT JOIN t2 ON t1.id1 = t2.id3 WHERE t2.id3 = 10`, `[]`)
+}
+
 func assertMatches(t *testing.T, conn *mysql.Conn, query, expected string) {
 	t.Helper()
 	qr := exec(t, conn, query)

go/vt/vtgate/planbuilder/abstract/left_join.go

@@ -34,10 +34,12 @@ var _ Operator = (*LeftJoin)(nil)
 // PushPredicate implements the Operator interface
 func (lj *LeftJoin) PushPredicate(expr sqlparser.Expr, semTable *semantics.SemTable) error {
 	deps := semTable.RecursiveDeps(expr)
-	if deps.IsSolvedBy(lj.Left.TableID()) {
+	switch {
+	case deps.IsSolvedBy(lj.Left.TableID()):
 		return lj.Left.PushPredicate(expr, semTable)
+	case deps.IsSolvedBy(lj.Right.TableID()):
+		return lj.Right.PushPredicate(expr, semTable)
 	}
-
 	return vterrors.Errorf(vtrpcpb.Code_INTERNAL, "Cannot push predicate: %s", sqlparser.String(expr))
 }
 

go/vt/vtgate/planbuilder/gen4_compare_v3_planner.go

@@ -37,15 +37,6 @@ func gen4CompareV3Planner(query string) func(sqlparser.Statement, *sqlparser.Res
 		// plan statement using Gen4
 		gen4Primitive, gen4Err := planWithPlannerVersion(statement, vars, ctxVSchema, query, Gen4)
 
-		// if onlyGen4 is set to true or Gen4's instruction contain a lock primitive,
-		// we use only Gen4's primitive and exit early without using V3's.
-		// since lock primitives can imply the creation or deletion of locks,
-		// we want to execute them once using Gen4 to avoid the duplicated locks
-		// or double lock-releases.
-		if onlyGen4 || hasLockPrimitive(gen4Primitive) {
-			return gen4Primitive, gen4Err
-		}
-
 		// get V3's plan
 		v3Primitive, v3Err := planWithPlannerVersion(statement, vars, ctxVSchema, query, V3)
 
@@ -55,6 +46,15 @@ func gen4CompareV3Planner(query string) func(sqlparser.Statement, *sqlparser.Res
 			return nil, err
 		}
 
+		// if onlyGen4 is set to true or Gen4's instruction contain a lock primitive,
+		// we use only Gen4's primitive and exit early without using V3's.
+		// since lock primitives can imply the creation or deletion of locks,
+		// we want to execute them once using Gen4 to avoid the duplicated locks
+		// or double lock-releases.
+		if onlyGen4 || hasLockPrimitive(gen4Primitive) {
+			return gen4Primitive, gen4Err
+		}
+
 		return &engine.Gen4CompareV3{
 			V3:         v3Primitive,
 			Gen4:       gen4Primitive,

go/vt/vtgate/planbuilder/route_planning.go

@@ -1142,6 +1142,7 @@ func createRoutePlanForOuter(ctx *planningContext, aRoute, bRoute *routeTree, ne
 			right: outer,
 			pred:  sqlparser.AndExpressions(joinPredicates...),
 		}),
+		predicates:  append(aRoute.predicates, bRoute.predicates...),
 		keyspace:    aRoute.keyspace,
 		vindexPreds: append(aRoute.vindexPreds, bRoute.vindexPreds...),
 	}

go/vt/vtgate/planbuilder/testdata/filter_cases.txt

@@ -670,6 +670,7 @@ Gen4 plan same as above
     "Vindex": "user_index"
   }
 }
+Gen4 plan same as above
 
 # Multi-route unique vindex constraint
 "select user_extra.id from user join user_extra on user.col = user_extra.col where user.id = 5"