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Fix missed lock acquisition while inlining new-style SQL functions.

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When starting to use a query parsetree loaded from the catalogs,
we must begin by applying AcquireRewriteLocks(), to obtain the same
relation locks that the parser would have gotten if the query were
entered interactively, and to do some other cleanup such as dealing
with later-dropped columns.  New-style SQL functions are just as
subject to this rule as other stored parsetrees; however, of the
places dealing with such functions, only init_sql_fcache had gotten
the memo.  In particular, if we successfully inlined a new-style
set-returning SQL function that contained any relation references,
we'd either get an assertion failure or attempt to use those
relation(s) sans locks.

I also added AcquireRewriteLocks calls to fmgr_sql_validator and
print_function_sqlbody.  Desultory experiments didn't demonstrate any
failures in those, but I suspect that I just didn't try hard enough.
Certainly we don't expect nearby code paths to operate without locks.

On the same logic of it-ought-to-have-the-same-effects-as-the-old-code,
call pg_rewrite_query() in fmgr_sql_validator, too.  It's possible
that neither code path there needs to bother with rewriting, but
doing the analysis to prove that is beyond my goals for today.

Per bug #17161 from Alexander Lakhin.

Discussion: https://postgr.es/m/17161-048a1cdff8422800@postgresql.org
This commit is contained in:
Tom Lane
2021-08-31 12:02:36 -04:00
parent bb466c6b09
commit 589be6f6c7
5 changed files with 64 additions and 20 deletions
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9
src/backend/optimizer/util/clauses.c
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@@ -43,6 +43,7 @@
#include "parser/parse_agg.h"
#include "parser/parse_coerce.h"
#include "parser/parse_func.h"
#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteManip.h"
#include "tcop/tcopprot.h"
#include "utils/acl.h"
@@ -4470,6 +4471,12 @@ inline_function(Oid funcid, Oid result_type, Oid result_collid,
if (list_length(querytree_list) != 1)
goto fail;
querytree = linitial(querytree_list);
/*
* Because we'll insist below that the querytree have an empty rtable
* and no sublinks, it cannot have any relation references that need
* to be locked or rewritten. So we can omit those steps.
*/
}
else
{
@@ -5022,6 +5029,8 @@ inline_set_returning_function(PlannerInfo *root, RangeTblEntry *rte)
goto fail;
querytree = linitial(querytree_list);
/* Acquire necessary locks, then apply rewriter. */
AcquireRewriteLocks(querytree, true, false);
querytree_list = pg_rewrite_query(querytree);
if (list_length(querytree_list) != 1)
goto fail;