Re: Pre-allocated free space for row

On K, 2005-08-31 at 16:50 +0900, Satoshi Nagayasu wrote:
> Simon Riggs wrote:
> >>4. Allow to repair fragmentation in each page.
> >>
> >>Because updates cause fragmentation in the page.
> >>
> >>So we need to keep large continuous free space in each page,
> >>if we want to get more effective on PCTFREE feature.
> > 
> > 
> > ...doesn't VACUUM already do that?
> 
> VACUUM generates a huge load because it repaires all pages
> on the table file.
> 
> I think (more light-weight) repairing on a single page
> is needed to maintain free space in the specific page.

There have been plans floating around for adding a more lightweight
vacuum, which uses something similar to FSM to keep track of pages which
need vacuuming. And possibly integreated with background writer to make
effective use of I/O resources.

I guess it could be used for this case of "cheap page cleanups" as well.

-- 
Hannu Krosing <hannu@skype.net>