Re: Idea for getting rid of VACUUM FREEZE on cold pages

On 27/05/2010, at 20.00, Josh Berkus <josh@agliodbs.com> wrote:

>
>> Well, maybe I'm confused here, but arranging things so that we NEVER
>> have to visit the page after initially writing it seems like it's
>> setting the bar almost impossibly high.
>
> That is the use case, though.  What I've encountered so far at 3  
> client
> sites is tables which are largely append-only, with a few selects and
> very few updates (< 2%) on recent data.   In general, once data gets
> flushed out of memory, it goes to disk and never gets recalled, and
> certainly not written.  Thinks are hunky-dory until we reach
> max_freeze_age, at which point the server has to chew through hundreds
> of gigabytes of old data just to freeze them, sometimes bringing the
> application to a halt in the process.

The data doesn't get in there in " no time" if autovacuum was aware of  
inserts too it would incrementally freeze the table as it grows.

It would still cause it to be read in again but not in a big chunck.

Couldn't pages that are totally filled by the same transaction, be  
frozen on the initial write?

Jesper - given my limited knowledge about how it works.