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
