Re: HOT and INSERT/DELETE

Pavan Deolasee wrote:
> On 8/9/07, Bruce Momjian <bruce@momjian.us> wrote:
> >
> > I was wondering about HOT behavior.
> >
> > Will an INSERT reuse rows no longer visible caused by an UPDATE or
> > DELETE, or if an UPDATE will reuse rows expired by an invisible DELETE?
> > It seems both of these would be possible and useful.
> 
> 
> 
> As the patch stands today, we don't take any pains to update the
> FSM information after pruning and defraging the page. So FSM would
> not consider the page for either INSERT or COLD UPDATE. Of course,
> the page can still be used for INSERT if relation->rd_targetblock is
> somehow set to this page.
> 
> OTOH UPDATE will always reuse the dead space of either expired
> updated rows or deleted rows or even aborted rows.

Well, that is very good news.

--  Bruce Momjian  <bruce@momjian.us>          http://momjian.us EnterpriseDB
http://www.enterprisedb.com
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