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help / color / mirror / Atom feedFrom: Laurenz Albe <laurenz.albe@cybertec.at>
To: Subramanian,Ramachandran <ramachandran.subramanian@alte-leipziger.de>
To: pgsql-novice@lists.postgresql.org <pgsql-novice@lists.postgresql.org>
Subject: Re: Why only some files have fsm and vm extensions
Date: Wed, 20 May 2026 05:51:19 -0700
Message-ID: <2e0b32980172f955362b7392a3a8949f86471ac5.camel@cybertec.at> (raw)
In-Reply-To: <6ad2ace1ccaa48c3a7fe41f785c359b3@alte-leipziger.de>
References: <6ad2ace1ccaa48c3a7fe41f785c359b3@alte-leipziger.de>
On Wed, 2026-05-20 at 09:48 +0000, Subramanian,Ramachandran wrote:
> I am beginning to read the internals of Postgres , got curious and looked at the actual files .
> I learnt that FSM contains the Space map and vm the visibility map for a given table.
>
> 1. Why only some tables have it and others do not?
The ones that don't have these files have never been processed by VACUUM.
> 2. Why for some tables fsm is bigger than the table itself?
Because the tables are very small.
Yours,
Laurenz Albe
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To: pgsql-novice@postgresql.org
Cc: laurenz.albe@cybertec.at, ramachandran.subramanian@alte-leipziger.de, pgsql-novice@lists.postgresql.org
Subject: Re: Why only some files have fsm and vm extensions
In-Reply-To: <2e0b32980172f955362b7392a3a8949f86471ac5.camel@cybertec.at>
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