Re: [HACKERS] Resurrecting per-page cleaner for btree

Ühel kenal päeval, K, 2006-07-26 kell 23:02, kirjutas Martijn van
Oosterhout:
> On Wed, Jul 26, 2006 at 12:47:57PM -0400, Greg Stark wrote:
> > Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> >
> > > So far, the case hasn't been made for retail vacuum even ignoring the
> > > not-so-immutable-function risk.
> >
> > Well the desire for it comes from a very well established need for dealing
> > with extremely large tales with relatively small hot spots. The basic problem
> > being that currently the cost of vacuum is proportional to the size of the
> > table rather than the amount of dead space. There's no link between those
> > variables (at least in one direction) and any time they're far out of whack it
> > means excruciating pain for the DBA.
>
> I thought the suggested solution for that was the dead space map. That
> way vacuum can ignore parts of the table that havn't changed...

It can ignore parts of the *table* but still has to scan full *indexes*.

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