Re: PostgreSQL clustering VS MySQL clustering

>From http://developer.postgresql.org/todo.php:

Maintain a map of recently-expired rows

This allows vacuum to reclaim free space without requiring a sequential
scan

On Sat, Jan 22, 2005 at 12:20:53PM -0500, Greg Stark wrote:
> Dawid Kuroczko <qnex42(at)gmail(dot)com> writes:
>
> > Quick thought -- would it be to possible to implement a 'partial VACUUM'
> > per analogiam to partial indexes?
>
> No.
>
> But it gave me another idea. Perhaps equally infeasible, but I don't see why.
>
> What if there were a map of modified pages. So every time any tuple was marked
> deleted it could be marked in the map as modified. VACUUM would only have to
> look at these pages. And if it could mark as free every tuple that was marked
> as deleted then it could unmark the page.
>
> The only downside I see is that this could be a source of contention on
> multi-processor machines running lots of concurrent update/deletes.
>
> --
> greg
>
>
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