Fix incorrect printing of queries with duplicated join names.

Given a query in which multiple JOIN nodes used the same alias
(which'd necessarily be in different sub-SELECTs), ruleutils.c
would assign the JOIN nodes distinct aliases for clarity ...
but then it forgot to print the modified aliases when dumping
the JOIN nodes themselves.  This results in a dump/reload hazard
for views, because the emitted query is flat-out incorrect:
Vars will be printed with table names that have no referent.

This has been wrong for a long time, so back-patch to all supported
branches.

Philip Dubé

Discussion: https://postgr.es/m/CY4PR2101MB080246F2955FF58A6ED1FEAC98140@CY4PR2101MB0802.namprd21.prod.outlook.com
This commit is contained in:
Tom Lane 2019-06-12 19:42:38 -04:00
parent e23338cec4
commit f95d8f8106
3 changed files with 54 additions and 2 deletions

View File

@ -10245,8 +10245,16 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
/* Yes, it's correct to put alias after the right paren ... */
if (j->alias != NULL)
{
/*
* Note that it's correct to emit an alias clause if and only if
* there was one originally. Otherwise we'd be converting a named
* join to unnamed or vice versa, which creates semantic
* subtleties we don't want. However, we might print a different
* alias name than was there originally.
*/
appendStringInfo(buf, " %s",
quote_identifier(j->alias->aliasname));
quote_identifier(get_rtable_name(j->rtindex,
context)));
get_column_alias_list(colinfo, context);
}
}

View File

@ -769,6 +769,41 @@ View definition:
FROM temp_view_test.tx1 tx1_1
WHERE tx1.y1 = tx1_1.f1));
-- Test aliasing of joins
create view view_of_joins as
select * from
(select * from (tbl1 cross join tbl2) same) ss,
(tbl3 cross join tbl4) same;
\d+ view_of_joins
View "testviewschm2.view_of_joins"
Column | Type | Collation | Nullable | Default | Storage | Description
--------+---------+-----------+----------+---------+---------+-------------
a | integer | | | | plain |
b | integer | | | | plain |
c | integer | | | | plain |
d | integer | | | | plain |
e | integer | | | | plain |
f | integer | | | | plain |
g | integer | | | | plain |
h | integer | | | | plain |
View definition:
SELECT ss.a,
ss.b,
ss.c,
ss.d,
same.e,
same.f,
same.g,
same.h
FROM ( SELECT same_1.a,
same_1.b,
same_1.c,
same_1.d
FROM (tbl1
CROSS JOIN tbl2) same_1) ss,
(tbl3
CROSS JOIN tbl4) same;
-- Test view decompilation in the face of column addition/deletion/renaming
create table tt2 (a int, b int, c int);
create table tt3 (ax int8, b int2, c numeric);
@ -1721,4 +1756,4 @@ select pg_get_ruledef(oid, true) from pg_rewrite
DROP SCHEMA temp_view_test CASCADE;
NOTICE: drop cascades to 27 other objects
DROP SCHEMA testviewschm2 CASCADE;
NOTICE: drop cascades to 62 other objects
NOTICE: drop cascades to 63 other objects

View File

@ -319,6 +319,15 @@ ALTER TABLE tmp1 RENAME TO tx1;
\d+ aliased_view_3
\d+ aliased_view_4
-- Test aliasing of joins
create view view_of_joins as
select * from
(select * from (tbl1 cross join tbl2) same) ss,
(tbl3 cross join tbl4) same;
\d+ view_of_joins
-- Test view decompilation in the face of column addition/deletion/renaming
create table tt2 (a int, b int, c int);