Re: Getting acces to MVCC version number

From: Jean-Luc Lachance <jllachan(at)nsd(dot)ca>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-sql(at)postgresql(dot)org, pgsql-general(at)postgresql(dot)org
Subject: Re: Getting acces to MVCC version number
Date: 2002-09-23 15:47:01
Message-ID: 3D8F3775.B5DD079@nsd.ca
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That is great! Thanks for the info.

Tom Lane wrote:
>
> Jean-Luc Lachance <jllachan(at)nsd(dot)ca> writes:
> > How about making available the MVCC last version number just like oid is
> > available. This would simplify a lot of table design. You know, having
> > to add a field "updated::timestamp" to detect when a record was updated
> > while viewing it (a la pgaccess).
> > That way, if the version number do not match, one would know that the
> > reccord was updated since last retrieved.
>
> > What do think?
>
> I think it's already there: see xmin and cmin. Depending on your needs,
> testing xmin might be enough (you'd only need to pay attention to cmin
> if you wanted to notice changes within your own transaction).
>
> regards, tom lane

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