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List:       postgresql-general
Subject:    Re: [HACKERS] vacuum, performance, and MVCC
From:       Mario Weilguni <mweilguni () sime ! com>
Date:       2006-06-22 14:44:04
Message-ID: 200606221644.04457.mweilguni () sime ! com
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Am Donnerstag, 22. Juni 2006 16:09 schrieb Csaba Nagy:
> > > [...]
> > > There has to be a more linear way of handling this scenario.
> >
> > So vacuum the table often.
>
> Good advice, except if the table is huge :-)
>
> Here we have for example some tables which are frequently updated but
> contain >100 million rows. Vacuuming that takes hours. And the dead row
> candidates are the ones which are updated again and again and looked up
> frequently...
>
> A good solution would be a new type of vacuum which does not need to do
> a full table scan but can clean the pending dead rows without that... I
> guess then I could vacuum really frequently those tables.

Now that there is autovaccum, why not think of something like continous 
vacuum? A background process that gets info about potential changed tuples, 
and vacuums them (only those tuples), possibly with honouring I/O needs of 
backgrounds (not steealing I/O from busy backends).

For sure not that easy as autovacuum. I'm pretty sure I've read something 
about partial vacuum lately, is somebody working on something like this?

Regards,
  Mario

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