| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-patches(at)postgresql(dot)org |
| Subject: | Re: Skipping VACUUM of indexes when no work required |
| Date: | 2005-12-07 17:40:56 |
| Message-ID: | 1133977256.2906.926.camel@localhost.localdomain |
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| Lists: | pgsql-patches |
On Wed, 2005-12-07 at 09:55 -0500, Tom Lane wrote:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > We discussed an optimization of VACUUM here
> > http://archives.postgresql.org/pgsql-hackers/2005-09/msg00046.php
> > that would allow VACUUM to complete faster by avoiding scanning the
> > indexes when no rows were removed from the heap by the VACUUM.
>
> Unfortunately I can't read that message right now because archives
> isn't responding, but this seems like a pretty bad idea to me.
> You still have to do the vacuum cleanup pass (at least in the btree
> case, and the only reason gist doesn't need it is it's not yet up
> to speed) so there's no real savings.
There are real savings; this is not a theoretical patch.
One pass of an index is faster than two, always.
Best Regards, Simon Riggs
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