From: | Senor <frio_cervesa(at)hotmail(dot)com> |
---|---|
To: | "pgsql-general(at)lists(dot)postgresql(dot)org" <pgsql-general(at)lists(dot)postgresql(dot)org> |
Subject: | Re: autovacuum_freeze_max_age on append-only tables |
Date: | 2022-04-22 03:14:19 |
Message-ID: | DM8PR01MB701673B76E3C89B0729D3833F7F79@DM8PR01MB7016.prod.exchangelabs.com |
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Lists: | pgsql-general |
Thank you both Laurenz and Peter.
Laurenz - It was an article you posted a couple years ago introducing
the V13 feature that got me thinking about the insert-only situation I had.
Peter - I had been improperly holding anti-wraparound and aggressive in
my mind as related in a way they are not. You cleared that up.
2 last questions (maybe):
Are the autovacuum_vacuum_cost_* settings handled any differently for
'to avoid wraparound' vacuums? I understand that it won't give up a lock
but I was expecting it to still back off due to cost and allow the query
with conflicting lock to proceed.
Is there any benefit to manually running a vacuum every so many inserts
as opposed to using autovacuum_freeze_max_age. And in this case should
it be a vacuum freeze. Rows are never updated or deleted except for the
occasional roll back due to dropped network connections.
Thanks again
-Senor
On 4/21/2022 6:35, Laurenz Albe wrote:
> On Wed, 2022-04-20 at 23:06 +0000, senor wrote:
>> I'm apparently needing an education on how this "to avoid wraparound" vacuum differs from
>> any other. I've seen it referenced as "more aggressive" but I'd like details.
> The difference is twofold, as far as I know:
>
> - it will not skip any pages just because it happens not to get a lock on them
> - it will refuse to die if the lock it holds on the table conflicts with a user lock
>
> Unless you are in the habit of taking strong locks on the table, you shouldn't
> notice a difference. Anti-wraparound VACUUM is a routine activity and does not
> interfere with DML, just like a normal VACUUM.
>
> Yours,
> Laurenz Albe
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