From: | Alexander Lakhin <exclusion(at)gmail(dot)com> |
---|---|
To: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
Cc: | "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org>, "andrew(at)dunslane(dot)net" <andrew(at)dunslane(dot)net> |
Subject: | Re: Random pg_upgrade test failure on drongo |
Date: | 2024-01-09 11:00:01 |
Message-ID: | 5b2d0f4b-9e79-cd13-b932-b1a9162b7205@gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Hello Amit,
09.01.2024 13:08, Amit Kapila wrote:
>
>> As to checkpoint_timeout, personally I would not increase it, because it
>> seems unbelievable to me that pg_restore (with the cluster containing only
>> two empty databases) can run for longer than 5 minutes. I'd rather
>> investigate such situation separately, in case we encounter it, but maybe
>> it's only me.
>>
> I feel it is okay to set a higher value of checkpoint_timeout due to
> the same reason though the probability is less. I feel here it is
> important to explain in the comments why we are using these settings
> in the new test. I have thought of something like: "During the
> upgrade, bgwriter or checkpointer could hold the file handle for some
> removed file. Now, during restore when we try to create the file with
> the same name, it errors out. This behavior is specific to only some
> specific Windows versions and the probability of seeing this behavior
> is higher in this test because we use wal_level as logical via
> allows_streaming => 'logical' which in turn sets shared_buffers as
> 1MB."
>
> Thoughts?
I would describe that behavior as "During upgrade, when pg_restore performs
CREATE DATABASE, bgwriter or checkpointer may flush buffers and hold a file
handle for pg_largeobject, so later TRUNCATE pg_largeobject command will
fail if OS (such as older Windows versions) doesn't remove an unlinked file
completely till it's open. ..."
Best regards,
Alexander
From | Date | Subject | |
---|---|---|---|
Next Message | Andrei Lepikhov | 2024-01-09 11:07:19 | Re: POC: GROUP BY optimization |
Previous Message | Richard Guo | 2024-01-09 10:48:59 | Re: Support "Right Semi Join" plan shapes |