Re: Vacuum: allow usage of more than 1GB of work mem

On Thu, Sep 15, 2016 at 12:22 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Tomas Vondra <tomas.vondra@2ndquadrant.com> writes:
>> On 09/14/2016 07:57 PM, Tom Lane wrote:
>>> People who are vacuuming because they are out of disk space will be very
>>> very unhappy with that solution.
>
>> The people are usually running out of space for data, while these files
>> would be temporary files placed wherever temp_tablespaces points to. I'd
>> argue if this is a source of problems, the people are already in deep
>> trouble due to sorts, CREATE INDEX, ... as those commands may also
>> generate a lot of temporary files.
>
> Except that if you are trying to recover disk space, VACUUM is what you
> are doing, not CREATE INDEX.  Requiring extra disk space to perform a
> vacuum successfully is exactly the wrong direction to be going in.
> See for example this current commitfest entry:
> https://commitfest.postgresql.org/10/649/
> Regardless of what you think of the merits of that patch, it's trying
> to solve a real-world problem.  And as Robert has already pointed out,
> making this aspect of VACUUM more complicated is not solving any
> pressing problem.  "But we made it faster" is going to be a poor answer
> for the next person who finds themselves up against the wall with no
> recourse.

I very much agree.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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