On 8/18/22 03:32, David Rowley wrote:
> On Thu, 18 Aug 2022 at 02:46, Tomas Vondra
> <tomas.von...@enterprisedb.com> wrote:
>> So I don't think the current costing is wrong, but it certainly is more
>> complex. But the test does not test what it intended - I have two ideas
>> how to make it work:
>>
>> 1) increase the number of rows in the table
>>
>> 2) increase cpu_operator_cost (for that one test?)
>>
>> 3) tweak the costing somehow, to increase the cost a bit
>
> Why not, 4) SET parallel_setup_cost = 0; there are plenty of other
> places we do just that so we get a parallel plan without having to
> generate enough cost to drown out the parallel worker startup cost.
>
> Here are a couple of patches to demo the idea.
>
Yeah, that's an option too. I should have mentioned it along with the
cpu_operator_cost.
BTW would you mind taking a look at the costing? I think it's fine, but
it would be good if someone not involved in the patch takes a look.
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
