Horton

Re: Re: reloption to prevent VACUUM from truncating empty pages at the end of relation

Julien Rouhaud <rjuju123@gmail.com>

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From: Julien Rouhaud <rjuju123@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>, Fujii Masao <masao.fujii@gmail.com>, Robert Haas <robertmhaas@gmail.com>, David Steele <david@pgmasters.net>, Andres Freund <andres@anarazel.de>, "Bossart, Nathan" <bossartn@amazon.com>, Tom Lane <tgl@sss.pgh.pa.us>, Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Michael Paquier <michael@paquier.xyz>, Laurenz Albe <laurenz.albe@cybertec.at>, "Jamison, Kirk" <k.jamison@jp.fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-04-04T13:06:47Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add TRUNCATE parameter to VACUUM.

  2. Add vacuum_truncate reloption.

  3. Allow VACUUM to be run with index cleanup disabled.

On Thu, Apr 4, 2019 at 1:23 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Thu, Apr 4, 2019 at 1:26 PM Tsunakawa, Takayuki
> <tsunakawa.takay@jp.fujitsu.com> wrote:
> >
> > From: Fujii Masao [mailto:masao.fujii@gmail.com]
> > > reloption for TOAST is also required?
> >
> > # I've come back to the office earlier than planned...
> >
> > Hm, there's no reason to not provide toast.vacuum_shrink_enabled.  Done with the attached patch.
> >
>
> Thank you for updating the patch!

+1!

> +    <term><literal>vacuum_shrink_enabled</literal>,
> <literal>toast.vacuum_shrink_enabled</literal>
> (<type>boolean</type>)</term>
> +    <listitem>
> +     <para>
> +     Enables or disables shrinking the table when it's vacuumed.
> +     This also applies to autovacuum.
> +     The default is true.  If true, VACUUM frees empty pages at the
> end of the table.
>
> "VACUUM" needs <command> or "vacuum" is more appropriate here?

also, the documentation should point out that freeing is not
guaranteed.  Something like

 +     The default is true.  If true, VACUUM will try to free empty
pages at the end of the table.

> I'm not sure the consensus we got here but we don't make the vacuum
> command option for this?

I don't think here's a clear consensus, but my personal vote is to add
it, with  SHRINK_TABLE = [ force_on | force_off | default ] (unless a
better proposal has been made already)