| From: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
|---|---|
| To: | Justin Pryzby <pryzby(at)telsasoft(dot)com> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Darafei Komяpa Praliaskouski <me(at)komzpa(dot)net>, pgsql-hackers(at)lists(dot)postgresql(dot)org, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Michael Banck <mbanck(at)gmx(dot)net> |
| Subject: | Re: Berserk Autovacuum (let's save next Mandrill) |
| Date: | 2020-03-17 21:01:15 |
| Message-ID: | ade9403df7c3051ad68b58e98710c408511a4491.camel@cybertec.at |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Tue, 2020-03-17 at 14:56 -0500, Justin Pryzby wrote:
> I still suggest scale_factor maximum of 1e10, like
> 4d54543efa5eb074ead4d0fadb2af4161c943044
>
> Which alows more effectively disabling it than a factor of 100, which would
> progress like: ~1, 1e2, 1e4, 1e6, 1e8, 1e10, ..
>
> I don't think that 1e4 would be a problem, but 1e6 and 1e8 could be. With
> 1e10, it's first vacuumed when there's 10billion inserts, if we didn't previous
> hit the n_dead threshold.
>
> I think that's ok? If one wanted to disable it up to 1e11 tuples, I think
> they'd disable autovacuum, or preferably just implement an vacuum job.
Assume a scale factor >= 1, for example 2, and n live tuples.
The table has just been vacuumed.
Now we insert m number tuples (which are live).
Then the condition
threshold + scale_factor * live_tuples < newly_inserted_tuples
becomes
10000000 + 2 * (n + m) < m
which can never be true for non-negative n and m.
So a scale factor >= 1 disables the feature.
Yours,
Laurenz Albe
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Justin Pryzby | 2020-03-17 21:07:02 | Re: Berserk Autovacuum (let's save next Mandrill) |
| Previous Message | Bruce Momjian | 2020-03-17 20:47:41 | Re: Error on failed COMMIT |