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help / color / mirror / Atom feedFrom: Laurenz Albe <laurenz.albe@cybertec.at>
To: Wells Oliver <wells.oliver@gmail.com>
To: pgsql-admin <pgsql-admin@postgresql.org>
Subject: Re: Materialized views & dead tuples
Date: Wed, 19 Jun 2024 09:27:27 +0200
Message-ID: <776e98bc5ded6b4cda83d1d5318f4186e4f8e344.camel@cybertec.at> (raw)
In-Reply-To: <CAOC+FBU1d_VXbWsx6fNXaANQCKD0SRLB4Tupm4dC-7JiU5rdhg@mail.gmail.com>
References: <CAOC+FBU1d_VXbWsx6fNXaANQCKD0SRLB4Tupm4dC-7JiU5rdhg@mail.gmail.com>
On Tue, 2024-06-18 at 15:28 -0700, Wells Oliver wrote:
> Apologies for the daft question, but I am surprised to see materialized views
> show up in pg_stat_user_tables with lots of dead tuples. These are rematerialized
> nightly and, I thought, this had the effect of replacing/recreating them anew.
> Can someone shed some light on this?
It makes a difference if you use REFRESH MATERIALIZED VIEW or
REFRESH MATERIALIZED VIEW CONCURRENTLY.
The first statement will just discard the materialized table and create it anew,
and you will never see a dead tuple.
The second statement executes the query and updates the materialized table, which
can lead to dead tuples just like a normal UPDATE or DELETE.
Yours,
Laurenz Albe
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To: pgsql-admin@postgresql.org
Cc: laurenz.albe@cybertec.at, wells.oliver@gmail.com
Subject: Re: Materialized views & dead tuples
In-Reply-To: <776e98bc5ded6b4cda83d1d5318f4186e4f8e344.camel@cybertec.at>
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