Horton

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

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>
Cc: 'Julien Rouhaud' <rjuju123@gmail.com>, Laurenz Albe <laurenz.albe@cybertec.at>, "Jamison, Kirk" <k.jamison@jp.fujitsu.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Amit Kapila <amit.kapila16@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Fujii Masao <masao.fujii@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-02-22T04:47:52Z
Lists: pgsql-hackers

Commits

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  1. Add TRUNCATE parameter to VACUUM.

  2. Add vacuum_truncate reloption.

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

On Fri, Feb 22, 2019 at 02:38:56AM +0000, Tsunakawa, Takayuki wrote:
> From: Julien Rouhaud [mailto:rjuju123@gmail.com]
>> FWIW, I prefer shrink over truncate, though I'd rather go with
>> vacuum_shink_enabled as suggested previously.
> 
> Thanks.  I'd like to leave a committer to choose the name.  FWIW, I
> chose shrink_enabled rather than vacuum_shrink_enabled because this
> property may be used in other shrink situations in the future.  What
> I imagined was that with the zheap, DELETE or some maintenance
> operation, not vacuum, may try to shrink the table.  I meant this
> property to indicate "whether this table shrinks or not" regardless
> of the specific operation that can shrink the table. 

I don't think that we want to use a too generic name and it seems more
natural to reflect the context where it is used in the parameter name.
If we were to shrink with a similar option for other contexts, we
would most likely use a different option.  Depending on the load
pattern, users should also be able to disable or enable a subset of
contexts as well.

So I agree with Julien that [auto]vacuum_shrink_enabled is more
adapted for this stuff.
--
Michael