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Commit1cd9356

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Fix caching of foreign-key-checking queries so that when a replan is needed,
we regenerate the SQL query text not merely the plan derived from it. Thisis needed to handle contingencies such as renaming of a table or columnused in an FK. Pre-8.3, such cases worked despite the lack of replanning(because the cached plan needn't actually change), so this is a regression.Per bug #4417 from Benjamin Bihler.
1 parent448950b commit1cd9356

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5 files changed

+103
-7
lines changed

5 files changed

+103
-7
lines changed

‎src/backend/executor/spi.c‎

Lines changed: 31 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.197 2008/07/18 20:26:06 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.198 2008/09/15 23:37:39 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -1367,6 +1367,36 @@ SPI_is_cursor_plan(SPIPlanPtr plan)
13671367
return false;
13681368
}
13691369

1370+
/*
1371+
* SPI_plan_is_valid --- test whether a SPI plan is currently valid
1372+
* (that is, not marked as being in need of revalidation).
1373+
*
1374+
* See notes for CachedPlanIsValid before using this.
1375+
*/
1376+
bool
1377+
SPI_plan_is_valid(SPIPlanPtrplan)
1378+
{
1379+
Assert(plan->magic==_SPI_PLAN_MAGIC);
1380+
if (plan->saved)
1381+
{
1382+
ListCell*lc;
1383+
1384+
foreach(lc,plan->plancache_list)
1385+
{
1386+
CachedPlanSource*plansource= (CachedPlanSource*)lfirst(lc);
1387+
1388+
if (!CachedPlanIsValid(plansource))
1389+
return false;
1390+
}
1391+
return true;
1392+
}
1393+
else
1394+
{
1395+
/* An unsaved plan is assumed valid for its (short) lifetime */
1396+
return true;
1397+
}
1398+
}
1399+
13701400
/*
13711401
* SPI_result_code_string --- convert any SPI return code to a string
13721402
*

‎src/backend/utils/adt/ri_triggers.c‎

Lines changed: 29 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -15,7 +15,7 @@
1515
*
1616
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
1717
*
18-
* $PostgreSQL: pgsql/src/backend/utils/adt/ri_triggers.c,v 1.109 2008/05/19 04:14:24 tgl Exp $
18+
* $PostgreSQL: pgsql/src/backend/utils/adt/ri_triggers.c,v 1.110 2008/09/15 23:37:39 tgl Exp $
1919
*
2020
* ----------
2121
*/
@@ -3615,6 +3615,7 @@ static SPIPlanPtr
36153615
ri_FetchPreparedPlan(RI_QueryKey*key)
36163616
{
36173617
RI_QueryHashEntry*entry;
3618+
SPIPlanPtrplan;
36183619

36193620
/*
36203621
* On the first call initialize the hashtable
@@ -3630,7 +3631,30 @@ ri_FetchPreparedPlan(RI_QueryKey *key)
36303631
HASH_FIND,NULL);
36313632
if (entry==NULL)
36323633
returnNULL;
3633-
returnentry->plan;
3634+
3635+
/*
3636+
* Check whether the plan is still valid. If it isn't, we don't want
3637+
* to simply rely on plancache.c to regenerate it; rather we should
3638+
* start from scratch and rebuild the query text too. This is to cover
3639+
* cases such as table/column renames. We depend on the plancache
3640+
* machinery to detect possible invalidations, though.
3641+
*
3642+
* CAUTION: this check is only trustworthy if the caller has already
3643+
* locked both FK and PK rels.
3644+
*/
3645+
plan=entry->plan;
3646+
if (plan&&SPI_plan_is_valid(plan))
3647+
returnplan;
3648+
3649+
/*
3650+
* Otherwise we might as well flush the cached plan now, to free a
3651+
* little memory space before we make a new one.
3652+
*/
3653+
entry->plan=NULL;
3654+
if (plan)
3655+
SPI_freeplan(plan);
3656+
3657+
returnNULL;
36343658
}
36353659

36363660

@@ -3653,11 +3677,13 @@ ri_HashPreparedPlan(RI_QueryKey *key, SPIPlanPtr plan)
36533677
ri_InitHashTables();
36543678

36553679
/*
3656-
* Add the new plan.
3680+
* Add the new plan. We might be overwriting an entry previously
3681+
* found invalid by ri_FetchPreparedPlan.
36573682
*/
36583683
entry= (RI_QueryHashEntry*)hash_search(ri_query_cache,
36593684
(void*)key,
36603685
HASH_ENTER,&found);
3686+
Assert(!found||entry->plan==NULL);
36613687
entry->plan=plan;
36623688
}
36633689

‎src/backend/utils/cache/plancache.c‎

Lines changed: 39 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -35,7 +35,7 @@
3535
* Portions Copyright (c) 1994, Regents of the University of California
3636
*
3737
* IDENTIFICATION
38-
* $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.21 2008/09/09 18:58:08 tgl Exp $
38+
* $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.22 2008/09/15 23:37:39 tgl Exp $
3939
*
4040
*-------------------------------------------------------------------------
4141
*/
@@ -571,6 +571,44 @@ ReleaseCachedPlan(CachedPlan *plan, bool useResOwner)
571571
MemoryContextDelete(plan->context);
572572
}
573573

574+
/*
575+
* CachedPlanIsValid: test whether the plan within a CachedPlanSource is
576+
* currently valid (that is, not marked as being in need of revalidation).
577+
*
578+
* This result is only trustworthy (ie, free from race conditions) if
579+
* the caller has acquired locks on all the relations used in the plan.
580+
*/
581+
bool
582+
CachedPlanIsValid(CachedPlanSource*plansource)
583+
{
584+
CachedPlan*plan;
585+
586+
/* Validity check that we were given a CachedPlanSource */
587+
Assert(list_member_ptr(cached_plans_list,plansource));
588+
589+
plan=plansource->plan;
590+
if (plan&& !plan->dead)
591+
{
592+
/*
593+
* Plan must have positive refcount because it is referenced by
594+
* plansource; so no need to fear it disappears under us here.
595+
*/
596+
Assert(plan->refcount>0);
597+
598+
/*
599+
* Although we don't want to acquire locks here, it still seems
600+
* useful to check for expiration of a transient plan.
601+
*/
602+
if (TransactionIdIsValid(plan->saved_xmin)&&
603+
!TransactionIdEquals(plan->saved_xmin,TransactionXmin))
604+
plan->dead= true;
605+
else
606+
return true;
607+
}
608+
609+
return false;
610+
}
611+
574612
/*
575613
* AcquireExecutorLocks: acquire locks needed for execution of a fully-planned
576614
* cached plan; or release them if acquire is false.

‎src/include/executor/spi.h‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $PostgreSQL: pgsql/src/include/executor/spi.h,v 1.66 2008/04/01 03:09:30 tgl Exp $
9+
* $PostgreSQL: pgsql/src/include/executor/spi.h,v 1.67 2008/09/15 23:37:40 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -118,6 +118,7 @@ extern intSPI_freeplan(SPIPlanPtr plan);
118118
externOidSPI_getargtypeid(SPIPlanPtrplan,intargIndex);
119119
externintSPI_getargcount(SPIPlanPtrplan);
120120
externboolSPI_is_cursor_plan(SPIPlanPtrplan);
121+
externboolSPI_plan_is_valid(SPIPlanPtrplan);
121122
externconstchar*SPI_result_code_string(intcode);
122123

123124
externHeapTupleSPI_copytuple(HeapTupletuple);

‎src/include/utils/plancache.h‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
99
* Portions Copyright (c) 1994, Regents of the University of California
1010
*
11-
* $PostgreSQL: pgsql/src/include/utils/plancache.h,v 1.13 2008/09/09 18:58:09 tgl Exp $
11+
* $PostgreSQL: pgsql/src/include/utils/plancache.h,v 1.14 2008/09/15 23:37:40 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -109,6 +109,7 @@ extern void DropCachedPlan(CachedPlanSource *plansource);
109109
externCachedPlan*RevalidateCachedPlan(CachedPlanSource*plansource,
110110
booluseResOwner);
111111
externvoidReleaseCachedPlan(CachedPlan*plan,booluseResOwner);
112+
externboolCachedPlanIsValid(CachedPlanSource*plansource);
112113
externTupleDescPlanCacheComputeResultDesc(List*stmt_list);
113114

114115
externvoidResetPlanCache(void);

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