Re: pgstattuple output? - Mailing list pgsql-general

From Michael Crozier
Subject Re: pgstattuple output?
Date
Msg-id 200601251923.37178.crozierm@conducivetech.com
Whole thread Raw
In response to Re: pgstattuple output?  (Michael Fuhr <mike@fuhr.org>)
Responses Re: pgstattuple output?  ("John D. Burger" <john@mitre.org>)
List pgsql-general
> > Why is there so much free space with no dead tuples?  This table has
> > likely had serveral columns added over time, is that part of the problem?
> > Indexes?
>
> An ordinary vacuum frees space for PostgreSQL's use but it doesn't
> shrink the table's file(s) and return space to the operating system;
> this remains true in the latest versions.

I think I see now, "dead" tuples are the tuples that have yet to be reclaimed
by vacuum, not tuples that are ready to be used. I'm still rather confused,
as this table is only modified via inserts.  No deletes or update operations
are ever performed.  Logically (ie "I don't really know the truth") this
table should have no free tuples or free space except for the remainder of
the last allocated page.

What I need to see is the free space map, but I don't think those
patches/functions exist for 7.3.  I'll go look around.

Thanks,

 Michael


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