Re: Freeze avoidance of very large table.

On Tue, Apr 21, 2015 at 08:39:37AM +0200, Andres Freund wrote:
> On 2015-04-20 17:13:29 -0400, Bruce Momjian wrote:
> > Didn't you think any of the TODO threads had workable solutions? And
> > don't expect adding an additional file per relation will be zero cost
> > --- added over the lifetime of 200M transactions, I question if this
> > approach would be a win.
>
> Note that normally you'd not run with a 200M transaction freeze max age
> on a busy server. Rather around a magnitude more.
>
> Think about this being used on a time partionioned table. Right now all
> the partitions have to be fully rescanned on a regular basis - quite
> painful. With something like this normally only the newest partitions
> will have to be.

My point is that for the life of 200M transactions, you would have the
overhead of an additional file per table in the file system, and updates
of that. I just don't know if the overhead over the long time period
would be smaller than the VACUUM FREEZE. It might be fine --- I don't
know. People seem to focus on the big activities, while many small
activities can lead to larger slowdowns.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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