vtgate planbuilder: verify same vindex

data/test/vtgate/filter_cases.txt

@@ -766,4 +766,4 @@
 # but they refer to different things. The first reference is to the outermost query,
 # and the second reference is to the the innermost 'from' subquery.
 "select id2 from user uu where id in (select id from user where id = uu.id and user.col in (select col from (select id from user_extra where user_id = 5) uu where uu.user_id = uu.id))"
-"unsupported: subquery and parent route to different shards"
+"unsupported: UNION or subquery on different shards: vindex values are different"

data/test/vtgate/schema_test.json

@@ -12,7 +12,7 @@
           "owner": "multicolvin"
         },
         "user_md5_index": {
-          "type": "hash_test"
+          "type": "unicode_loose_md5"
         },
         "music_user_map": {
           "type": "lookup_test",

data/test/vtgate/unsupported_cases.txt

@@ -1,6 +1,6 @@
 # Unions
 "select * from user union select * from user_extra"
-"unsupported: UNION on multi-shard queries"
+"unsupported: UNION or subquery containing multi-shard queries"
 
 # SET
 "set a=1"
@@ -29,11 +29,11 @@
 
 # union operations in subqueries (FROM)
 "select * from (select * from user union all select * from user_extra) as t"
-"unsupported: UNION on multi-shard queries"
+"unsupported: UNION or subquery containing multi-shard queries"
 
 # union operations in subqueries (expressions)
 "select * from user where id in (select * from user union select * from user_extra)"
-"unsupported: UNION on multi-shard queries"
+"unsupported: UNION or subquery containing multi-shard queries"
 
 # subquery with join primitive (expressions)
 "select * from user where id in (select user.id from user join user_extra)"
@@ -77,11 +77,11 @@
 
 # subquery does not depend on unique vindex of outer query
 "select id from user where id in (select user_id from user_extra where user_extra.user_id = user.col)"
-"unsupported: subquery does not depend on scatter outer query"
+"unsupported: UNION or subquery containing multi-shard queries"
 
 # subquery does not depend on scatter outer query
 "select id from user where id in (select user_id from user_extra where user_extra.user_id = 4)"
-"unsupported: subquery does not depend on scatter outer query"
+"unsupported: UNION or subquery containing multi-shard queries"
 
 # subquery depends on a cross-shard subquery
 "select id from (select user.id, user.col from user join user_extra) as t where id in (select t.col from user)"
@@ -105,7 +105,7 @@
 
 # subquery and outer query route to different shards
 "select id from user where id = 5 and id in (select user_id from user_extra where user_extra.user_id = 4)"
-"unsupported: subquery and parent route to different shards"
+"unsupported: UNION or subquery on different shards: vindex values are different"
 
 # last_insert_id for sharded keyspace
 "select last_insert_id() from user"
@@ -433,7 +433,7 @@
 
 # multi-shard union
 "(select id from user union select id from music) union select 1 from dual"
-"unsupported: UNION on multi-shard queries"
+"unsupported: UNION or subquery containing multi-shard queries"
 
 # multi-shard union
 "select 1 from music union (select id from user union all select name from unsharded)"
@@ -445,15 +445,19 @@
 
 # multi-shard union
 "select id from user union all select id from music"
-"unsupported: UNION on multi-shard queries"
+"unsupported: UNION or subquery containing multi-shard queries"
+
+# union with the same target shard because of vindex
+"select * from music where id = 1 union select * from user where id = 1"
+"unsupported: UNION or subquery on different shards: vindexes are different"
 
 # union with different target shards
 "select 1 from music where id = 1 union select 1 from music where id = 2"
-"unsupported: UNION queries with different target shards"
+"unsupported: UNION or subquery on different shards: vindex values are different"
 
 # Union all
 "select col1, col2 from user union all select col1, col2 from user_extra"
-"unsupported: UNION on multi-shard queries"
+"unsupported: UNION or subquery containing multi-shard queries"
 
 "(select user.id, user.name from user join user_extra where user_extra.extra = 'asdf') union select 'b','c' from user"
 "unsupported construct: SELECT of UNION is non-trivial"

go/vt/vtgate/planbuilder/from.go

@@ -276,10 +276,8 @@ func (pb *primitiveBuilder) join(rpb *primitiveBuilder, ajoin *sqlparser.JoinTab
 		}
 
 		// Both l & r routes point to the same shard.
-		if lRoute.ERoute.Opcode == engine.SelectEqualUnique && rRoute.ERoute.Opcode == engine.SelectEqualUnique {
-			if valEqual(lRoute.condition, rRoute.condition) {
-				return pb.mergeRoutes(rpb, ajoin)
-			}
+		if lRoute.isSameShardedRoute(rRoute) == nil {
+			return pb.mergeRoutes(rpb, ajoin)
 		}
 	}
 

go/vt/vtgate/planbuilder/route.go

@@ -622,14 +622,7 @@ func (rb *route) SubqueryCanMerge(pb *primitiveBuilder, inner *route) error {
 	default:
 		return errors.New("unsupported: scatter subquery")
 	}
-
-	if rb.ERoute.Opcode != engine.SelectEqualUnique {
-		return errors.New("unsupported: subquery does not depend on scatter outer query")
-	}
-	if !valEqual(rb.condition, inner.condition) {
-		return errors.New("unsupported: subquery and parent route to different shards")
-	}
-	return nil
+	return rb.isSameShardedRoute(inner)
 }
 
 // UnionCanMerge returns nil if the supplied route that represents
@@ -654,12 +647,21 @@ func (rb *route) UnionCanMerge(right *route) error {
 		}
 		return errIntermixingUnsupported
 	}
+	return rb.isSameShardedRoute(right)
+}
 
+// isSameShardedRoute returns nil if the supplied route has
+// the same single shard target as the current route. If not, it
+// returns an appropriate error.
+func (rb *route) isSameShardedRoute(right *route) error {
 	if rb.ERoute.Opcode != engine.SelectEqualUnique || right.ERoute.Opcode != engine.SelectEqualUnique {
-		return errors.New("unsupported: UNION on multi-shard queries")
+		return errors.New("unsupported: UNION or subquery containing multi-shard queries")
+	}
+	if rb.ERoute.Vindex != right.ERoute.Vindex {
+		return errors.New("unsupported: UNION or subquery on different shards: vindexes are different")
 	}
 	if !valEqual(rb.condition, right.condition) {
-		return errors.New("unsupported: UNION queries with different target shards")
+		return errors.New("unsupported: UNION or subquery on different shards: vindex values are different")
 	}
 	return nil
 }