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Re: DELETE with LIMIT (or my first hack)

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Jaime Casanova <jaime(at)2ndquadrant(dot)com>, Daniel Loureiro <loureirorg(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: DELETE with LIMIT (or my first hack)
Date: 2010-11-30 22:21:07
Message-ID: 1291155667.11789.6.camel@jdavis-ux.asterdata.local (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On Tue, 2010-11-30 at 15:52 -0500, Robert Haas wrote:
> On Tue, Nov 30, 2010 at 2:45 PM, Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
> > On Tue, 2010-11-30 at 11:12 -0500, Robert Haas wrote:
> >>
> >> Could you possibly have ModifyTable -> Limit -> MergeAppend?
> >
> > Before MergeAppend knows which tuple to produce, it needs to see the
> > tuples (at least the first one from each of its children), meaning that
> > it needs to pull them through ModifyTable; and at that point it's
> > already too late.
> >
> You seem to be imagining the MergeAppend node on top

Yes, I assumed that the tuples flowed in the direction of the arrows ;)

Now that I think about it, your representation makes some sense given
our EXPLAIN output.

	Jeff Davis

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