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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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51
src/backend/executor/nodeLockRows.c
View File

@ -58,12 +58,13 @@ lnext:
/*
* Attempt to lock the source tuple(s). (Note we only have locking
* rowmarks in lr_rowMarks.)
* rowmarks in lr_arowMarks.)
*/
epq_started = false;
foreach(lc, node->lr_rowMarks)
foreach(lc, node->lr_arowMarks)
{
ExecRowMark *erm = (ExecRowMark *) lfirst(lc);
ExecAuxRowMark *aerm = (ExecAuxRowMark *) lfirst(lc);
ExecRowMark *erm = aerm->rowmark;
Datum datum;
bool isNull;
HeapTupleData tuple;
@ -84,7 +85,7 @@ lnext:
Oid tableoid;
datum = ExecGetJunkAttribute(slot,
erm->toidAttNo,
aerm->toidAttNo,
&isNull);
/* shouldn't ever get a null result... */
if (isNull)
@ -101,7 +102,7 @@ lnext:
/* fetch the tuple's ctid */
datum = ExecGetJunkAttribute(slot,
erm->ctidAttNo,
aerm->ctidAttNo,
&isNull);
/* shouldn't ever get a null result... */
if (isNull)
@ -189,9 +190,10 @@ lnext:
* so as to avoid overhead in the common case where there are no
* concurrent updates.)
*/
foreach(lc, node->lr_rowMarks)
foreach(lc, node->lr_arowMarks)
{
ExecRowMark *erm = (ExecRowMark *) lfirst(lc);
ExecAuxRowMark *aerm = (ExecAuxRowMark *) lfirst(lc);
ExecRowMark *erm = aerm->rowmark;
HeapTupleData tuple;
Buffer buffer;
@ -251,6 +253,7 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
{
LockRowsState *lrstate;
Plan *outerPlan = outerPlan(node);
List *epq_arowmarks;
ListCell *lc;
/* check for unsupported flags */
@ -262,7 +265,6 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
lrstate = makeNode(LockRowsState);
lrstate->ps.plan = (Plan *) node;
lrstate->ps.state = estate;
EvalPlanQualInit(&lrstate->lr_epqstate, estate, outerPlan, node->epqParam);
/*
* Miscellaneous initialization
@ -288,15 +290,17 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
lrstate->ps.ps_ProjInfo = NULL;
/*
* Locate the ExecRowMark(s) that this node is responsible for. (InitPlan
* should already have built the global list of ExecRowMarks.)
* Locate the ExecRowMark(s) that this node is responsible for, and
* construct ExecAuxRowMarks for them. (InitPlan should already have
* built the global list of ExecRowMarks.)
*/
lrstate->lr_rowMarks = NIL;
lrstate->lr_arowMarks = NIL;
epq_arowmarks = NIL;
foreach(lc, node->rowMarks)
{
PlanRowMark *rc = (PlanRowMark *) lfirst(lc);
ExecRowMark *erm = NULL;
ListCell *lce;
ExecRowMark *erm;
ExecAuxRowMark *aerm;
Assert(IsA(rc, PlanRowMark));
@ -304,16 +308,9 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
if (rc->isParent)
continue;
foreach(lce, estate->es_rowMarks)
{
erm = (ExecRowMark *) lfirst(lce);
if (erm->rti == rc->rti)
break;
erm = NULL;
}
if (erm == NULL)
elog(ERROR, "failed to find ExecRowMark for PlanRowMark %u",
rc->rti);
/* find ExecRowMark and build ExecAuxRowMark */
erm = ExecFindRowMark(estate, rc->rti);
aerm = ExecBuildAuxRowMark(erm, outerPlan->targetlist);
/*
* Only locking rowmarks go into our own list. Non-locking marks are
@ -322,11 +319,15 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
* do an EPQ recheck.
*/
if (RowMarkRequiresRowShareLock(erm->markType))
lrstate->lr_rowMarks = lappend(lrstate->lr_rowMarks, erm);
lrstate->lr_arowMarks = lappend(lrstate->lr_arowMarks, aerm);
else
EvalPlanQualAddRowMark(&lrstate->lr_epqstate, erm);
epq_arowmarks = lappend(epq_arowmarks, aerm);
}
/* Now we have the info needed to set up EPQ state */
EvalPlanQualInit(&lrstate->lr_epqstate, estate,
outerPlan, epq_arowmarks, node->epqParam);
return lrstate;
}