Re: pg_restore --multi-thread

Andrew Dunstan wrote:
> Cédric Villemain wrote:
>>
>> -j [jobs], --jobs[=jobs]
>> Specifies the number of jobs (pg_restore) to run simultaneously.
>> If the -j
>> option is given without an argument, pg_restore will not limit the
>> number of
>> jobs that can run simultaneously.

> Quite apart from anything else, this description is almost 100% dead
> wrong. The argument is not optional at all, and there is no unlimited
> parallelism. If you want to know how it actually works look at the dev
> docs.

What I'm still missing here is a piece of documentation or a guideline
that says when a given number of threads/jobs/workers would be
appropriate. For make -j, this is pretty clear: If you have N CPUs to
spare, use -j N. For pg_restore, this is not made clear: Is it the
number of CPUs on the client or the server or the number of disks on the
client or the server or perhaps a combination of this or something else?