Re: which work memory parameter is used for what?

På onsdag 09. november 2016 kl. 15:54:13, skrev Adrian Klaver <
adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)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(at)hogranch(dot)com <mailto:pierce(at)hogranch(dot)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.
 
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