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

On 5 September 2016 at 15:50, Claudio Freire <klaussfreire@gmail.com> wrote:
> On Sun, Sep 4, 2016 at 3:46 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> On 3 September 2016 at 04:25, Claudio Freire <klaussfreire@gmail.com> wrote:
>>> The patch also makes vacuum free the dead_tuples before starting
>>> truncation. It didn't seem necessary to hold onto it beyond that
>>> point, and it might help give the OS more cache, especially if work
>>> mem is configured very high to avoid multiple index scans.
>>
>> How long does that part ever take? Is there any substantial gain from this?
>>
>> Lets discuss that as a potential second patch.
>
> In the test case I mentioned, it takes longer than the vacuum part itself.

Please provide a test case and timings so we can see what's happening.

-- 
Simon Riggs                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services