From: | Marko Tiikkaja <marko(dot)tiikkaja(at)cs(dot)helsinki(dot)fi> |
---|---|
To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
Cc: | Merlin Moncure <mmoncure(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Review of Writeable CTE Patch |
Date: | 2010-01-26 15:16:53 |
Message-ID: | 4B5F0765.9050909@cs.helsinki.fi |
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Lists: | pgsql-hackers |
On 2010-01-26 17:11, Alvaro Herrera wrote:
> Merlin Moncure escribió:
>
>> *) CopySnapshot was promoted from static. Is this legal/good idea?
>> Is a wrapper more appropriate?
>
> Hmm ... I wonder why isn't the patch doing RegisterSnapshot with the
> passed snapshot directly -- why is it necessary to create a new copy of
> it? (I notice that only one of the arms in that "if" creates a copy;
> if that is correct, I think it warrants a comment explaining why).
Per discussion here:
http://archives.postgresql.org/pgsql-hackers/2009-11/msg01964.php the
executor copies the snapshot if it plans on modifying it. A comment
explaining this might be in order.
> If the copy is necessary (e.g. because the snapshot must not be modified
> externally, and there's actual risk that it is), then maybe it would be
> better to create a new function RegisterSnapshotCopy instead?
Sounds reasonable.
Regards,
Marko Tiikkaja
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