Hi Rob,
Thanks, I will try.
It’s a bit of a bummer though, because I just started to use flywaydb to
manage migrations, and it wraps all migrations into a single transaction.
So I have to do this outside of the tool.
I will still try to evaluate if locking has any effect, to have a better
understanding of how postgres works under the hood.
Best Regards,
Daniel
-----Original Message-----
From: Luca Ferrari [mailto:fluca1978@gmail.com]
Sent: Friday, August 9, 2019 3:58 PM
To: Daniel Fink (PDF) <daniel.fink@pdf.com>
Cc: pgsql-general <pgsql-general@lists.postgresql.org>
Subject: Re: pg_wal fills up on big update query
On Wed, Aug 7, 2019 at 3:34 PM Daniel Fink (PDF) <daniel.fink@pdf.com>
wrote:
> My current idea is to lock both tables completely from access (the queried
> and the updated one) so that postgresql does not have to ensure isolation
> for concurrent queries by keeping a copy of each row.
I'm not sure that locking will prevent the snapshotting and the WAL
machinery, but someone more expert on the are could clarify this.
Since the column is nullable, I would apply it outside of the transaction,
and then do the update. If that still fails, I would try to split the update
on small chunks (after all, it's an update, so it is smething you can line
up data).
Luca
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