From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>
Cc: Tobias Gierke <tobias.gierke@code-sourcery.de>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: Linear slow-down while inserting into a table with an ON INSERT trigger ?
Date: Sat, 17 Jul 2021 10:33:09 -0400
Message-ID: <62962.1626532389@sss.pgh.pa.us> (raw)
In-Reply-To: <CAApHDvr-kFAmOihG1FxVZfgdV_e5TR8cU3n+QPkYwJ8XqmA4YQ@mail.gmail.com>
References: <62070f97-13e7-df73-bed1-f8e48c12bf2d@code-sourcery.de>
<20210717044026.GA19498@telsasoft.com>
<CAApHDvr-kFAmOihG1FxVZfgdV_e5TR8cU3n+QPkYwJ8XqmA4YQ@mail.gmail.com>
David Rowley <dgrowleyml@gmail.com> writes:
> On Sat, 17 Jul 2021 at 16:40, Justin Pryzby <pryzby@telsasoft.com> wrote:
>> You could run a single UPDATE rather than 30k triggers.
>> Or switch to an INSERT on the table, with an index on it, and call
>> max(last_parent_table_change) from whatever needs to ingest it. And prune the
>> old entries and vacuum it outside the transaction. Maybe someone else will
>> have a better suggestion.
> Maybe just change the UPDATE statement to:
> UPDATE data_sync SET last_parent_table_change=CURRENT_TIMESTAMP WHERE
> last_parent_table_change <> CURRENT_TIMESTAMP;
> That should reduce the number of actual updates to 1 per transaction.
Or, if it's impractical to make the application do that for itself,
this could be a job for suppress_redundant_updates_trigger().
https://www.postgresql.org/docs/current/functions-trigger.html
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, dgrowleyml@gmail.com, pryzby@telsasoft.com, tobias.gierke@code-sourcery.de
Subject: Re: Linear slow-down while inserting into a table with an ON INSERT trigger ?
In-Reply-To: <62962.1626532389@sss.pgh.pa.us>
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