*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.264 2006/01/11 08:43:12 neilc Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.265 2006/01/12 21:48:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
newSlot = EvalPlanQual(estate,
erm->rti,
&update_ctid,
- update_xmax);
+ update_xmax,
+ estate->es_snapshot->curcid);
if (!TupIsNull(newSlot))
{
slot = newSlot;
epqslot = EvalPlanQual(estate,
resultRelInfo->ri_RangeTableIndex,
&update_ctid,
- update_xmax);
+ update_xmax,
+ estate->es_snapshot->curcid);
if (!TupIsNull(epqslot))
{
*tupleid = update_ctid;
epqslot = EvalPlanQual(estate,
resultRelInfo->ri_RangeTableIndex,
&update_ctid,
- update_xmax);
+ update_xmax,
+ estate->es_snapshot->curcid);
if (!TupIsNull(epqslot))
{
*tupleid = update_ctid;
* rti - rangetable index of table containing tuple
* *tid - t_ctid from the outdated tuple (ie, next updated version)
* priorXmax - t_xmax from the outdated tuple
+ * curCid - command ID of current command of my transaction
*
* *tid is also an output parameter: it's modified to hold the TID of the
* latest version of the tuple (note this may be changed even on failure)
*/
TupleTableSlot *
EvalPlanQual(EState *estate, Index rti,
- ItemPointer tid, TransactionId priorXmax)
+ ItemPointer tid, TransactionId priorXmax, CommandId curCid)
{
evalPlanQual *epq;
EState *epqstate;
continue; /* loop back to repeat heap_fetch */
}
+ /*
+ * If tuple was inserted by our own transaction, we have to check
+ * cmin against curCid: cmin >= curCid means our command cannot
+ * see the tuple, so we should ignore it. Without this we are
+ * open to the "Halloween problem" of indefinitely re-updating
+ * the same tuple. (We need not check cmax because
+ * HeapTupleSatisfiesDirty will consider a tuple deleted by
+ * our transaction dead, regardless of cmax.) We just checked
+ * that priorXmax == xmin, so we can test that variable instead
+ * of doing HeapTupleHeaderGetXmin again.
+ */
+ if (TransactionIdIsCurrentTransactionId(priorXmax) &&
+ HeapTupleHeaderGetCmin(tuple.t_data) >= curCid)
+ {
+ ReleaseBuffer(buffer);
+ return NULL;
+ }
+
/*
* We got tuple - now copy it for use by recheck query.
*/