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Fix PlanRowMark/ExecRowMark structures to handle inheritance correctly.

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In an inherited UPDATE/DELETE, each target table has its own subplan,
because it might have a column set different from other targets.  This
means that the resjunk columns we add to support EvalPlanQual might be
at different physical column numbers in each subplan.  The EvalPlanQual
rewrite I did for 9.0 failed to account for this, resulting in possible
misbehavior or even crashes during concurrent updates to the same row,
as seen in a recent report from Gordon Shannon.  Revise the data structure
so that we track resjunk column numbers separately for each subplan.

I also chose to move responsibility for identifying the physical column
numbers back to executor startup, instead of assuming that numbers derived
during preprocess_targetlist would stay valid throughout subsequent
massaging of the plan.  That's a bit slower, so we might want to consider
undoing it someday; but it would complicate the patch considerably and
didn't seem justifiable in a bug fix that has to be back-patched to 9.0.
This commit is contained in:
Tom Lane
2011-01-12 20:47:02 -05:00
parent 7a32ff9732
commit d487afbb81
12 changed files with 193 additions and 123 deletions
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107
src/backend/executor/execMain.c
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@ -744,9 +744,6 @@ InitPlan(QueryDesc *queryDesc, int eflags)
erm->prti = rc->prti;
erm->markType = rc->markType;
erm->noWait = rc->noWait;
erm->ctidAttNo = rc->ctidAttNo;
erm->toidAttNo = rc->toidAttNo;
erm->wholeAttNo = rc->wholeAttNo;
ItemPointerSetInvalid(&(erm->curCtid));
estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
}
@ -1386,6 +1383,71 @@ ExecConstraints(ResultRelInfo *resultRelInfo,
}
/*
* ExecFindRowMark -- find the ExecRowMark struct for given rangetable index
*/
ExecRowMark *
ExecFindRowMark(EState *estate, Index rti)
{
ListCell *lc;
foreach(lc, estate->es_rowMarks)
{
ExecRowMark *erm = (ExecRowMark *) lfirst(lc);
if (erm->rti == rti)
return erm;
}
elog(ERROR, "failed to find ExecRowMark for rangetable index %u", rti);
return NULL; /* keep compiler quiet */
}
/*
* ExecBuildAuxRowMark -- create an ExecAuxRowMark struct
*
* Inputs are the underlying ExecRowMark struct and the targetlist of the
* input plan node (not planstate node!). We need the latter to find out
* the column numbers of the resjunk columns.
*/
ExecAuxRowMark *
ExecBuildAuxRowMark(ExecRowMark *erm, List *targetlist)
{
ExecAuxRowMark *aerm = (ExecAuxRowMark *) palloc0(sizeof(ExecAuxRowMark));
char resname[32];
aerm->rowmark = erm;
/* Look up the resjunk columns associated with this rowmark */
if (erm->relation)
{
Assert(erm->markType != ROW_MARK_COPY);
/* if child rel, need tableoid */
if (erm->rti != erm->prti)
{
snprintf(resname, sizeof(resname), "tableoid%u", erm->prti);
aerm->toidAttNo = ExecFindJunkAttributeInTlist(targetlist,
resname);
}
/* always need ctid for real relations */
snprintf(resname, sizeof(resname), "ctid%u", erm->prti);
aerm->ctidAttNo = ExecFindJunkAttributeInTlist(targetlist,
resname);
}
else
{
Assert(erm->markType == ROW_MARK_COPY);
snprintf(resname, sizeof(resname), "wholerow%u", erm->prti);
aerm->wholeAttNo = ExecFindJunkAttributeInTlist(targetlist,
resname);
}
return aerm;
}
/*
* EvalPlanQual logic --- recheck modified tuple(s) to see if we want to
* process the updated version under READ COMMITTED rules.
@ -1676,11 +1738,13 @@ EvalPlanQualFetch(EState *estate, Relation relation, int lockmode,
/*
* EvalPlanQualInit -- initialize during creation of a plan state node
* that might need to invoke EPQ processing.
* Note: subplan can be NULL if it will be set later with EvalPlanQualSetPlan.
*
* Note: subplan/auxrowmarks can be NULL/NIL if they will be set later
* with EvalPlanQualSetPlan.
*/
void
EvalPlanQualInit(EPQState *epqstate, EState *estate,
Plan *subplan, int epqParam)
Plan *subplan, List *auxrowmarks, int epqParam)
{
/* Mark the EPQ state inactive */
epqstate->estate = NULL;
@ -1688,7 +1752,7 @@ EvalPlanQualInit(EPQState *epqstate, EState *estate,
epqstate->origslot = NULL;
/* ... and remember data that EvalPlanQualBegin will need */
epqstate->plan = subplan;
epqstate->rowMarks = NIL;
epqstate->arowMarks = auxrowmarks;
epqstate->epqParam = epqParam;
}
@ -1698,25 +1762,14 @@ EvalPlanQualInit(EPQState *epqstate, EState *estate,
* We need this so that ModifyTuple can deal with multiple subplans.
*/
void
EvalPlanQualSetPlan(EPQState *epqstate, Plan *subplan)
EvalPlanQualSetPlan(EPQState *epqstate, Plan *subplan, List *auxrowmarks)
{
/* If we have a live EPQ query, shut it down */
EvalPlanQualEnd(epqstate);
/* And set/change the plan pointer */
epqstate->plan = subplan;
}
/*
* EvalPlanQualAddRowMark -- add an ExecRowMark that EPQ needs to handle.
*
* Currently, only non-locking RowMarks are supported.
*/
void
EvalPlanQualAddRowMark(EPQState *epqstate, ExecRowMark *erm)
{
if (RowMarkRequiresRowShareLock(erm->markType))
elog(ERROR, "EvalPlanQual doesn't support locking rowmarks");
epqstate->rowMarks = lappend(epqstate->rowMarks, erm);
/* The rowmarks depend on the plan, too */
epqstate->arowMarks = auxrowmarks;
}
/*
@ -1766,13 +1819,17 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
Assert(epqstate->origslot != NULL);
foreach(l, epqstate->rowMarks)
foreach(l, epqstate->arowMarks)
{
ExecRowMark *erm = (ExecRowMark *) lfirst(l);
ExecAuxRowMark *aerm = (ExecAuxRowMark *) lfirst(l);
ExecRowMark *erm = aerm->rowmark;
Datum datum;
bool isNull;
HeapTupleData tuple;
if (RowMarkRequiresRowShareLock(erm->markType))
elog(ERROR, "EvalPlanQual doesn't support locking rowmarks");
/* clear any leftover test tuple for this rel */
EvalPlanQualSetTuple(epqstate, erm->rti, NULL);
@ -1788,7 +1845,7 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
Oid tableoid;
datum = ExecGetJunkAttribute(epqstate->origslot,
erm->toidAttNo,
aerm->toidAttNo,
&isNull);
/* non-locked rels could be on the inside of outer joins */
if (isNull)
@ -1804,7 +1861,7 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
/* fetch the tuple's ctid */
datum = ExecGetJunkAttribute(epqstate->origslot,
erm->ctidAttNo,
aerm->ctidAttNo,
&isNull);
/* non-locked rels could be on the inside of outer joins */
if (isNull)
@ -1829,7 +1886,7 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
/* fetch the whole-row Var for the relation */
datum = ExecGetJunkAttribute(epqstate->origslot,
erm->wholeAttNo,
aerm->wholeAttNo,
&isNull);
/* non-locked rels could be on the inside of outer joins */
if (isNull)