Re: Choosing parallel_degree

On 06/04/2016 07:38, Amit Kapila wrote:
> On Tue, Apr 5, 2016 at 11:55 PM, Julien Rouhaud
>>
>> In alter_table.sgml, I didn't comment the lock level needed to modify
>> parallel_degree since it requires an access exclusive lock for now.
>> While thinking about it, I think it's safe to use a share update
>> exclusive lock but I may be wrong.  What do you think?
>>
>
> We require to keep AccessExclusiveLock for operations which can impact
> Select operation which I think this operation does, so lets
> retain AccessExclusiveLock for now.  If somebody else thinks, we should
> not bother about Selects, then we can change it.
>

Ok. Isn't there also some considerations about forcing replanning of
prepared statements using the table for instance?

>>
>> I find your version better once again, but should we keep some
>> consistency between them or it's not important?
>>
>
> I think consistency is good, but this is different from
> max_parallel_degree, so I would prefer to use something on lines of what
> I have mentioned.
>

Agreed, changed in attached v8 (including fix for previous mail).

--
Julien Rouhaud
http://dalibo.com - http://dalibo.org