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Prevent planner from including temp tables of other backends when expanding

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an inheritance tree.  Per recent discussions.
This commit is contained in:
Tom Lane 2005-08-02 20:27:45 +00:00
parent 558730ac6b
commit 688784f671
1 changed files with 23 additions and 1 deletions
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24
src/backend/optimizer/prep/prepunion.c
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@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.125 2005/07/28 22:27:00 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.126 2005/08/02 20:27:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -22,6 +22,7 @@
#include "access/heapam.h"
#include "catalog/namespace.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "optimizer/clauses.h"
@ -807,6 +808,16 @@ expand_inherited_rtentry(PlannerInfo *root, Index rti)
RangeTblEntry *childrte;
Index childRTindex;
/*
* It is possible that the parent table has children that are
* temp tables of other backends. We cannot safely access such
* tables (because of buffering issues), and the best thing to do
* seems to be to silently ignore them.
*/
if (childOID != parentOID &&
isOtherTempNamespace(get_rel_namespace(childOID)))
continue;
/*
* Build an RTE for the child, and attach to query's rangetable
* list. We copy most fields of the parent's RTE, but replace
@ -820,6 +831,17 @@ expand_inherited_rtentry(PlannerInfo *root, Index rti)
inhRTIs = lappend_int(inhRTIs, childRTindex);
}
/*
* If all the children were temp tables, pretend it's a non-inheritance
* situation. The duplicate RTE we added for the parent table is harmless.
*/
if (list_length(inhRTIs) < 2)
{
/* Clear flag to save repeated tests if called again */
rte->inh = false;
return NIL;
}
/*
* The executor will check the parent table's access permissions when
* it examines the parent's inheritlist entry. There's no need to