From: Scott Ribe <scott_ribe@elevated-dev.com>
To: Jef Mortelle <jefmortelle@gmail.com>
Cc: pgsql-admin@lists.postgresql.org
Subject: Re: Upgrade from PG12 to PG
Date: Thu, 20 Jul 2023 08:51:35 -0600
Message-ID: <B6D3FD80-5794-47B8-9074-E10C4945951B@elevated-dev.com> (raw)
In-Reply-To: <dc88d14d-6d0f-2d67-ecfc-c7495bf1c22b@gmail.com>
References: <3901e0da-819b-5b6d-bb57-c29f6d384725@gmail.com>
<CAG95seWz3dJxKQPg4_3EAEBCXUuJTDpZBUKAp0+bqP2amQaZ9g@mail.gmail.com>
<dc88d14d-6d0f-2d67-ecfc-c7495bf1c22b@gmail.com>
> On Jul 20, 2023, at 7:46 AM, Jef Mortelle <jefmortelle@gmail.com> wrote:
>
> So: not possible to have very little downtime if you have a database with al lot rows containing text as datatype, as pg_upgrade needs 12hr for 24 milj rows in pg_largeobject.
We need to get terminology straight, as at the moment your posts are very confusing. In PostgreSQL large objects and text are not the same. Text is basically varchar without a specified length limit. Large object is a blob (but not what SQL calls a BLOB)--it is kind of like a file stored outside the normal table mechanism, and provides facilities for partial reads, etc: https://www.postgresql.org/docs/15/largeobjects.html. There are a number of ways to wind up with references to large objects all deleted, but the orphaned large objects still in the database.
First thing you should do: run lovacuum -n to find out if you have orphaned large objects. If so, start cleaning those up, then see how long pg_upgrade takes.
Second, what's your hardware? I really don't see dump & restore of a 1TB database taking 6 hours.
> Alsready tried to use --link and --jobs, but you cannot ommit the "select lo_unlink ...." for every rows containing datatype text in your database that the pg_* program creates in the export/dump file.
Terminology again, or are you conflating two different issues? pg_upgrade --link does not create a dump file.
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To: pgsql-admin@postgresql.org
Cc: scott_ribe@elevated-dev.com, jefmortelle@gmail.com, pgsql-admin@lists.postgresql.org
Subject: Re: Upgrade from PG12 to PG
In-Reply-To: <B6D3FD80-5794-47B8-9074-E10C4945951B@elevated-dev.com>
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