From: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: reloption to prevent VACUUM from truncating empty pages at the end of relation |
Date: | 2018-04-19 20:38:02 |
Message-ID: | 20180419203802.hqrb4o2wexjnb2ft@alvherre.pgsql |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Andres Freund wrote:
> On 2018-04-19 16:56:59 -0300, Alvaro Herrera wrote:
> > Michael Paquier wrote:
> >
> > > Then, let's consider the beginning of the first commit fest of v12 as
> > > judgement. Implementing radix tree for shared buffers is a long-term
> > > project, which has no guarantee to get merged, while a visibly-simple
> > > reloptions which helps in some cases...
> >
> > In the scenario we studied, the truncations were causing periodic
> > hiccups which were quite severe.
>
> Was that with the current logic of breaking the truncations into smaller
> chunks?
Yes -- it was with 9.5.7. I was skeptical about that stuff working
correctly for a toast table, BTW, but I didn't manage to prove anything.
> > The truncations were completely useless anyway because the table
> > grew back to the original size daily (a few dozen GBs I think).
> > That was a lot of unnecessary work, and under exclusive lock no
> > less.
>
> FWIW, One goal of the different buffer mapping implementation is to also
> make both increasing and decreasing size of relations possible without
> an AEL.
Oh, that sounds very useful.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
From | Date | Subject | |
---|---|---|---|
Next Message | Alvaro Herrera | 2018-04-19 20:49:46 | Re: Repeated crashes in GENERATED ... AS IDENTITY tests |
Previous Message | Andres Freund | 2018-04-19 20:23:58 | Re: reloption to prevent VACUUM from truncating empty pages at the end of relation |