which work memory parameter is used for what?

Hello,

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?

Thanks

--
-h