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Fix incorrect printing of queries with duplicated join names.

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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 ddc053dc50
commit 3d99a81397
3 changed files with 55 additions and 2 deletions
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10
src/backend/utils/adt/ruleutils.c
View File

@ -10309,8 +10309,16 @@ 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);
}
}