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

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