Re: Calculation for Max_FSM_pages : Any rules of thumb? - Mailing list pgsql-general

From Vivek Khera
Subject Re: Calculation for Max_FSM_pages : Any rules of thumb?
Date
Msg-id A99C2241-71B1-451B-804E-F9B53412C720@khera.org
Whole thread Raw
In response to Calculation for Max_FSM_pages : Any rules of thumb?  (Ow Mun Heng <Ow.Mun.Heng@wdc.com>)
Responses Re: Calculation for Max_FSM_pages : Any rules of thumb?  (Bill Moran <wmoran@potentialtech.com>)
List pgsql-general
On Nov 1, 2007, at 8:51 PM, Ow Mun Heng wrote:

> Another question is, based on what I've read in the archives (in my
> laptop.. No-Inet conn @ work) Since I've overran my max_FSM, I'm
> basically screwed and will have to do a vacuum verbose FULL on the
> entire DB. Crap..

I've seen this repeated many times as well, and I can't think of a
really good reason why this should be true.  Once you increase max fsm
pages, won't the very next regular vacuum find all the free space in
pages and add them to the map anyway?  Ie, you've not "lost" any free
space once the next regular vacuum runs.  At worst, you've got a
slightly bloated table because you allocated more pages rather than re-
using some, but is that worth a full vacuum?  I don't think it will be
unless you're *way* under the fsm pages needed and have been for a
long time.


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