diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/parser/parse_clause.c | 5 | ||||
| -rw-r--r-- | src/backend/parser/parse_relation.c | 15 | ||||
| -rw-r--r-- | src/test/regress/expected/join.out | 24 | ||||
| -rw-r--r-- | src/test/regress/sql/join.sql | 12 |
4 files changed, 52 insertions, 4 deletions
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c index 64c423c9d0a..a9ecc2399db 100644 --- a/src/backend/parser/parse_clause.c +++ b/src/backend/parser/parse_clause.c @@ -721,14 +721,15 @@ transformFromClauseItem(ParseState *pstate, Node *n, * we always push them into the namespace, but mark them as not * lateral_ok if the jointype is wrong. * + * Notice that we don't require the merged namespace list to be + * conflict-free. See the comments for scanNameSpaceForRefname(). + * * NB: this coding relies on the fact that list_concat is not * destructive to its second argument. */ lateral_ok = (j->jointype == JOIN_INNER || j->jointype == JOIN_LEFT); setNamespaceLateralState(l_namespace, true, lateral_ok); - checkNameSpaceConflicts(pstate, pstate->p_namespace, l_namespace); - sv_namespace_length = list_length(pstate->p_namespace); pstate->p_namespace = list_concat(pstate->p_namespace, l_namespace); diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c index 42de89f5101..d473749e303 100644 --- a/src/backend/parser/parse_relation.c +++ b/src/backend/parser/parse_relation.c @@ -131,6 +131,18 @@ refnameRangeTblEntry(ParseState *pstate, * Search the query's table namespace for an RTE matching the * given unqualified refname. Return the RTE if a unique match, or NULL * if no match. Raise error if multiple matches. + * + * Note: it might seem that we shouldn't have to worry about the possibility + * of multiple matches; after all, the SQL standard disallows duplicate table + * aliases within a given SELECT level. Historically, however, Postgres has + * been laxer than that. For example, we allow + * SELECT ... FROM tab1 x CROSS JOIN (tab2 x CROSS JOIN tab3 y) z + * on the grounds that the aliased join (z) hides the aliases within it, + * therefore there is no conflict between the two RTEs named "x". However, + * if tab3 is a LATERAL subquery, then from within the subquery both "x"es + * are visible. Rather than rejecting queries that used to work, we allow + * this situation, and complain only if there's actually an ambiguous + * reference to "x". */ static RangeTblEntry * scanNameSpaceForRefname(ParseState *pstate, const char *refname, int location) @@ -175,8 +187,7 @@ scanNameSpaceForRefname(ParseState *pstate, const char *refname, int location) /* * Search the query's table namespace for a relation RTE matching the * given relation OID. Return the RTE if a unique match, or NULL - * if no match. Raise error if multiple matches (which shouldn't - * happen if the namespace was checked correctly when it was created). + * if no match. Raise error if multiple matches. * * See the comments for refnameRangeTblEntry to understand why this * acts the way it does. diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out index c94ac614af8..7c3c9aced20 100644 --- a/src/test/regress/expected/join.out +++ b/src/test/regress/expected/join.out @@ -3092,6 +3092,24 @@ SELECT * FROM (5 rows) rollback; +-- bug #8444: we've historically allowed duplicate aliases within aliased JOINs +select * from + int8_tbl x join (int4_tbl x cross join int4_tbl y) j on q1 = f1; -- error +ERROR: column reference "f1" is ambiguous +LINE 2: ..._tbl x join (int4_tbl x cross join int4_tbl y) j on q1 = f1; + ^ +select * from + int8_tbl x join (int4_tbl x cross join int4_tbl y) j on q1 = y.f1; -- error +ERROR: invalid reference to FROM-clause entry for table "y" +LINE 2: ...bl x join (int4_tbl x cross join int4_tbl y) j on q1 = y.f1; + ^ +HINT: There is an entry for table "y", but it cannot be referenced from this part of the query. +select * from + int8_tbl x join (int4_tbl x cross join int4_tbl y(ff)) j on q1 = f1; -- ok + q1 | q2 | f1 | ff +----+----+----+---- +(0 rows) + -- -- Test LATERAL -- @@ -3946,6 +3964,12 @@ ERROR: invalid reference to FROM-clause entry for table "a" LINE 1: ...m int4_tbl a full join lateral generate_series(0, a.f1) g on... ^ DETAIL: The combining JOIN type must be INNER or LEFT for a LATERAL reference. +-- check we complain about ambiguous table references +select * from + int8_tbl x cross join (int4_tbl x cross join lateral (select x.f1) ss); +ERROR: table reference "x" is ambiguous +LINE 2: ...cross join (int4_tbl x cross join lateral (select x.f1) ss); + ^ -- LATERAL can be used to put an aggregate into the FROM clause of its query select 1 from tenk1 a, lateral (select max(a.unique1) from int4_tbl b) ss; ERROR: aggregate functions are not allowed in FROM clause of their own query level diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql index 351400f2da2..07ad2708633 100644 --- a/src/test/regress/sql/join.sql +++ b/src/test/regress/sql/join.sql @@ -890,6 +890,15 @@ SELECT * FROM rollback; +-- bug #8444: we've historically allowed duplicate aliases within aliased JOINs + +select * from + int8_tbl x join (int4_tbl x cross join int4_tbl y) j on q1 = f1; -- error +select * from + int8_tbl x join (int4_tbl x cross join int4_tbl y) j on q1 = y.f1; -- error +select * from + int8_tbl x join (int4_tbl x cross join int4_tbl y(ff)) j on q1 = f1; -- ok + -- -- Test LATERAL -- @@ -1077,5 +1086,8 @@ select f1,g from int4_tbl a cross join (select a.f1 as g) ss; -- SQL:2008 says the left table is in scope but illegal to access here select f1,g from int4_tbl a right join lateral generate_series(0, a.f1) g on true; select f1,g from int4_tbl a full join lateral generate_series(0, a.f1) g on true; +-- check we complain about ambiguous table references +select * from + int8_tbl x cross join (int4_tbl x cross join lateral (select x.f1) ss); -- LATERAL can be used to put an aggregate into the FROM clause of its query select 1 from tenk1 a, lateral (select max(a.unique1) from int4_tbl b) ss; |