Re: which work memory parameter is used for what? - Mailing list pgsql-general
På onsdag 09. november 2016 kl. 15:54:13, skrev Adrian Klaver <adrian.klaver@aklaver.com>:
On 11/08/2016 06:45 PM, Andreas Joseph Krogh wrote:
> På onsdag 09. november 2016 kl. 03:02:54, skrev John R Pierce
> <pierce@hogranch.com <mailto:pierce@hogranch.com>>:
>
> On 11/8/2016 2:34 PM, Hector Yuen wrote:
> > I am confused on which are the parameters for different queries. I am
> > trying to run VACUUM on a big table, and it is easier for me to set
> > the work memory for the specific session instead of tuning it in
> > postgresql.conf.
> >
> > I noticed that if I do:
> >
> > set work_mem='1GB';
> >
> > it doesn't help VACUUM, I have to do:
> >
> > set maintenance_work_mem='1GB';
> >
> > to accelerate the operation. I could notice that by running VACUUM
> > VERBOSE and see that the table was scanned less times an the operation
> > finished a lot faster.
> >
> > My question is, for which operations does work_mem matter and for
> > which ones does maintenance_work_mem do? I am specially interested in
> > operations like ANALYZE and VACUUM, I believe ANALYZE depends on
> > work_mem and VACUUM on maintenance_work_mem.
> >
> > Can you confirm my understanding?
> >
>
> https://www.postgresql.org/docs/current/static/runtime-config-resource.html
>
>
> maintenance_work_mem is used by vacuum and create index operations
> (including implicit index creation such as add foreign key).
>
>
> There is no such thing in PG.
Can you be more specific as;
https://www.postgresql.org/docs/9.5/static/runtime-config-resource.html#GUC-MAINTENANCE-WORK-MEM
"implicit index creation such as add foreign key"
No implicit index will be created.
-- 
Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
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