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Support UPDATE/DELETE WHERE CURRENT OF cursor_name, per SQL standard.

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Along the way, allow FOR UPDATE in non-WITH-HOLD cursors; there may once
have been a reason to disallow that, but it seems to work now, and it's
really rather necessary if you want to select a row via a cursor and then
update it in a concurrent-safe fashion.

Original patch by Arul Shaji, rather heavily editorialized by Tom Lane.
This commit is contained in:
Tom Lane
2007-06-11 01:16:30 +00:00
parent 85d72f0516
commit 6808f1b1de
30 changed files with 940 additions and 127 deletions
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25
src/backend/executor/nodeTidscan.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeTidscan.c,v 1.53 2007/01/05 22:19:28 momjian Exp $
* $PostgreSQL: pgsql/src/backend/executor/nodeTidscan.c,v 1.54 2007/06/11 01:16:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -61,8 +61,8 @@ TidListCreate(TidScanState *tidstate)
/*
* We initialize the array with enough slots for the case that all quals
* are simple OpExprs. If there's any ScalarArrayOpExprs, we may have to
* enlarge the array.
* are simple OpExprs or CurrentOfExprs. If there are any
* ScalarArrayOpExprs, we may have to enlarge the array.
*/
numAllocTids = list_length(evalList);
tidList = (ItemPointerData *)
@ -148,6 +148,25 @@ TidListCreate(TidScanState *tidstate)
pfree(ipdatums);
pfree(ipnulls);
}
else if (expr && IsA(expr, CurrentOfExpr))
{
CurrentOfExpr *cexpr = (CurrentOfExpr *) expr;
ItemPointerData cursor_tid;
if (execCurrentOf(cexpr->cursor_name,
RelationGetRelid(tidstate->ss.ss_currentRelation),
&cursor_tid))
{
if (numTids >= numAllocTids)
{
numAllocTids *= 2;
tidList = (ItemPointerData *)
repalloc(tidList,
numAllocTids * sizeof(ItemPointerData));
}
tidList[numTids++] = cursor_tid;
}
}
else
elog(ERROR, "could not identify CTID expression");
}