Re: max_fsm_pages >800k ... ? - Mailing list pgsql-hackers

From Tom Lane
Subject Re: max_fsm_pages >800k ... ?
Date
Msg-id 10677.1118898624@sss.pgh.pa.us
Whole thread Raw
In response to max_fsm_pages >800k ... ?  ("Marc G. Fournier" <scrappy@postgresql.org>)
List pgsql-hackers
"Marc G. Fournier" <scrappy@postgresql.org> writes:
> Without more information to provide at this time, does the following seem 
> "unusual"?

> INFO:  free space map: 252 relations, 411494 pages stored; 738640 total pages needed
> DETAIL:  Allocated FSM size: 2000 relations + 400000 pages = 2463 kB shared memory.

What this is saying is that you'd need 738640 fsm_pages slots to
remember every single page that has a useful amount of free space.
However, you don't necessarily have to remember all those pages.
If you remember enough pages to satisfy insert/update requests
until the next VACUUM happens, then you're good.

I think the bottom-line question is "are you seeing any database
bloat?"  If yes, increase max_fsm_pages; if no, worry not.
        regards, tom lane


pgsql-hackers by date:

Previous
From: Christopher Kings-Lynne
Date:
Subject: Re: [GENERAL] INHERITS and planning
Next
From: Greg Stark
Date:
Subject: Re: [GENERAL] INHERITS and planning