Fix anti-join correctess bug

enginetest/join_op_tests.go

@@ -395,6 +395,36 @@ var DefaultJoinOpTests = []joinOpTest{
 			},
 		},
 	},
+	{
+		name: "empty join tests",
+		setup: [][]string{
+			setup.MydbData[0],
+			{
+				"CREATE table xy (x int primary key, y int);",
+				"CREATE table uv (u int primary key, v int);",
+				"insert into xy values (1,0), (2,1), (0,2), (3,3);",
+				"insert into uv values (0,1), (1,1), (2,2), (3,2);",
+			},
+		},
+		tests: []JoinOpTests{
+			{
+				Query:    "select * from xy where y-1 = (select u from uv where u = 4);",
+				Expected: []sql.Row{},
+			},
+			{
+				Query:    "select * from xy where x = 1 and x != (select u from uv where u = 4);",
+				Expected: []sql.Row{{1, 0}},
+			},
+			{
+				Query:    "select * from xy where x = 1 and x not in (select u from uv where u = 4);",
+				Expected: []sql.Row{{1, 0}},
+			},
+			{
+				Query:    "select * from xy where x = 1 and not exists (select u from uv where u = 4);",
+				Expected: []sql.Row{{1, 0}},
+			},
+		},
+	},
 	{
 		name: "issue 5633, nil comparison in merge join",
 		setup: [][]string{

enginetest/join_planning_tests.go

@@ -494,14 +494,24 @@ order by 1;`,
 		},
 		tests: []JoinPlanTest{
 			{
-				q:     "select * from xy where y-1 = (select u from uv limit 1 offset 5);",
+				q:     "select * from xy where y-1 = (select u from uv where u = 4);",
 				types: []plan.JoinType{plan.JoinTypeSemi},
 				exp:   []sql.Row{},
 			},
 			{
-				q:     "select * from xy where x != (select u from uv limit 1 offset 5);",
-				types: []plan.JoinType{plan.JoinTypeAnti},
-				exp:   []sql.Row{},
+				q:     "select * from xy where x = 1 and x != (select u from uv where u = 4);",
+				types: []plan.JoinType{plan.JoinTypeLeftOuter},
+				exp:   []sql.Row{{1, 0}},
+			},
+			{
+				q:     "select * from xy where x = 1 and x not in (select u from uv where u = 4);",
+				types: []plan.JoinType{plan.JoinTypeLeftOuter},
+				exp:   []sql.Row{{1, 0}},
+			},
+			{
+				q:     "select * from xy where x = 1 and not exists (select u from uv where u = 4);",
+				types: []plan.JoinType{plan.JoinTypeLeftOuter},
+				exp:   []sql.Row{{1, 0}},
 			},
 		},
 	},

sql/rowexec/join_iters.go

@@ -283,7 +283,6 @@ func (i *existsIter) Next(ctx *sql.Context) (sql.Row, error) {
 			}
 			left = i.parentRow.Append(r)
 			rIter, err = i.b.Build(ctx, i.secondaryProvider, left)
-
 			if err != nil {
 				return nil, err
 			}
@@ -315,13 +314,6 @@ func (i *existsIter) Next(ctx *sql.Context) (sql.Row, error) {
 			if i.typ.IsSemi() {
 				// reset iter, no match
 				nextState = esIncLeft
-			} else if !i.rightIterNonEmpty && !isTrueLit(i.cond) {
-				// ANTI_JOIN with empty RHS is subject to special cases,
-				// the first two are a valid match.
-				//   1) If we matched no rows but rows were returned
-				//   2) No match and no rows returned, EXISTS check
-				//   3) No match and no rows returned, IN check
-				return nil, io.EOF
 			} else {
 				nextState = esRet
 			}