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Commit6997f22

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Fix ExecOpenScanRelation to take a lock on a ROW_MARK_COPY relation.
ExecOpenScanRelation assumed that any relation listed in the ExecRowMarklist has been locked by InitPlan; but this is not true if the rel'smarkType is ROW_MARK_COPY, which is possible if it's a foreign table.In most (possibly all) cases, failure to acquire a lock here isn't reallyproblematic because the parser, planner, or plancache would have taken theappropriate lock already. In principle though it might leave us vulnerableto working with a relation that we hold no lock on, and in any case if theexecutor isn't depending on previously-taken locks otherwise then it shouldnot do so for ROW_MARK_COPY relations.Noted by Etsuro Fujita. Back-patch to all active versions, since theinconsistency has been there a long time. (It's almost certainlyirrelevant in 9.0, since that predates foreign tables, but the code'sstill wrong on its own terms.)
1 parent40b0c10 commit6997f22

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lines changed

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‎src/backend/executor/execMain.c‎

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Original file line numberDiff line numberDiff line change
@@ -704,6 +704,10 @@ InitPlan(QueryDesc *queryDesc, int eflags)
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if (rc->isParent)
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continue;
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/*
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* If you change the conditions under which rel locks are acquired
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* here, be sure to adjust ExecOpenScanRelation to match.
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*/
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switch (rc->markType)
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{
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caseROW_MARK_EXCLUSIVE:

‎src/backend/executor/execUtils.c‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -816,7 +816,9 @@ ExecOpenScanRelation(EState *estate, Index scanrelid)
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{
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ExecRowMark*erm=lfirst(l);
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if (erm->rti==scanrelid)
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/* Keep this check in sync with InitPlan! */
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if (erm->rti==scanrelid&&
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erm->relation!=NULL)
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{
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lockmode=NoLock;
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break;

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