Re: incoherent dead tuples between pg_stat_user_tables and pgstattuple?

From: Luca Ferrari <fluca1978(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-general <pgsql-general(at)postgresql(dot)org>
Subject: Re: incoherent dead tuples between pg_stat_user_tables and pgstattuple?
Date: 2019-09-27 14:29:37
Message-ID: CAKoxK+5YZMZZjt7kY0yqLE2J6+nrAE7BDE_BNYnfnvHP5e9qsg@mail.gmail.com
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On Fri, Sep 27, 2019 at 3:52 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> n_live_tup/n_dead_tup should not be thought to be better than
> approximations. Most operations adjust them only incrementally,
> and messages to the stats collector can get dropped entirely
> under heavy load, causing deltas to go missing. There are
> also race conditions involved in some update scenarios.
>

Are you suggesting tha autovacuum made free space available so that
pg_stat_user_tables lags behind? Because I don't see last_autovacuum
changing in the mantime.

Luca

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