| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Marko Tiikkaja <marko(dot)tiikkaja(at)cs(dot)helsinki(dot)fi> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Writeable CTEs and empty relations |
| Date: | 2010-02-10 01:20:52 |
| Message-ID: | 1977.1265764852@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Marko Tiikkaja <marko(dot)tiikkaja(at)cs(dot)helsinki(dot)fi> writes:
> On 2010-02-10 02:19 +0200, Tom Lane wrote:
>> You still haven't explained why it's a good idea to change the snapshot
>> after the executor has started. Right at the moment I'm prepared to
>> reject the patch on that ground alone.
> The patch only touches the snapshot's curcid. That's needed to allow
> the queries see the tuples of the DML WITHs ran before that particular
> query.
... and they will also see, for example, tuples inserted by triggers
fired by those queries. I thought the plan for this feature was to
store and re-read the RETURNING data, not to go back and re-read the
underlying tables.
regards, tom lane
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