Re: Automatic free space map filling - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Automatic free space map filling
Date
Msg-id 11395.1141230732@sss.pgh.pa.us
Whole thread Raw
In response to Re: Automatic free space map filling  (Peter Eisentraut <peter_e@gmx.net>)
Responses Re: Automatic free space map filling
Re: Automatic free space map filling
List pgsql-hackers
Peter Eisentraut <peter_e@gmx.net> writes:
> I'm not sure if I made myself clear.  The idea is that you fill the free-space 
> map early with opportunitistic entries in the hope that most updates and 
> deletes go through "soon".  That is, these entries will be invalid for a 
> short time but hopefully by the time another write looks at them, the entries 
> will have become valid.  That way you don't actually have to run vacuum on 
> these deleted rows.

How does an optimistic FSM entry avoid the need to run vacuum?  All that
will happen is that some backend will visit the page and not find usable
free space.
        regards, tom lane


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