From: | Joe Conway <mail(at)joeconway(dot)com> |
---|---|
To: | Bruce Momjian <bruce(at)momjian(dot)us> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Hackers (PostgreSQL)" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: VALUES clause memory optimization |
Date: | 2006-08-26 20:08:03 |
Message-ID: | 44F0AA23.9030800@joeconway.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-docs pgsql-hackers pgsql-patches |
Bruce Momjian wrote:
> Has this been addressed?
>
>>Tom Lane wrote:
>>>The reason we could safely list_free inside transformInsertRow is that
>>>we know all its callers have just built the passed-in list and so there
>>>are no other pointers to it. That doesn't apply in the general case of
>>>grammar output.
After another look, even in this case there could be other pointers.
Starting around line 667 of analyze.c:
8<------------------
foreach(lc, selectQuery->targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
Expr *expr;
if (tle->resjunk)
continue;
if (tle->expr &&
(IsA(tle->expr, Const) ||IsA(tle->expr, Param)) &&
exprType((Node *) tle->expr) == UNKNOWNOID)
expr = tle->expr;
else
expr = (Expr *) makeVar(rtr->rtindex,
tle->resno,
exprType((Node *) tle->expr),
exprTypmod((Node *) tle->expr),
0);
exprList = lappend(exprList, expr);
}
/* Prepare row for assignment to target table */
exprList = transformInsertRow(pstate, exprList,
stmt->cols,
icolumns, attrnos);
8<------------------
So in the UNKNOWNOID case, it wouldn't be safe to free the node after
transformation because it originates in the grammar output. The *only*
safe thing to free up would be a the input exprList itself. Not much to
be saved there.
>>>My advice is to get that low-hanging fruit
>>>in transformInsertRow and leave the other ideas for 8.3.
This one case doesn't provide that much memory savings by itself anyway.
I guess we'll just live with it until we can come up with a safe way to
free grammar output.
Joe
From | Date | Subject | |
---|---|---|---|
Next Message | Joshua D. Drake | 2006-08-26 20:31:08 | Re: [HACKERS] New XML section for documentation |
Previous Message | David Fetter | 2006-08-26 18:56:41 | Re: [HACKERS] New XML section for documentation |
From | Date | Subject | |
---|---|---|---|
Next Message | Joshua D. Drake | 2006-08-26 20:31:08 | Re: [HACKERS] New XML section for documentation |
Previous Message | Jim C. Nasby | 2006-08-26 19:48:43 | Re: [Pgsqlrpms-hackers] Safer auto-initdb for RPM init script |
From | Date | Subject | |
---|---|---|---|
Next Message | Alvaro Herrera | 2006-08-27 01:03:20 | Re: Hierarchical Queries--Status |
Previous Message | Zoltan Boszormenyi | 2006-08-26 19:36:14 | Re: [HACKERS] Performance testing of COPY (SELECT) TO |