Re: Removing unneeded self joins

On 6/7/21 13:49, Hywel Carver wrote:
> On Mon, Jul 5, 2021 at 2:20 PM Andrey Lepikhov 
> <a.lepikhov@postgrespro.ru <mailto:a.lepikhov@postgrespro.ru>> wrote:
> Looking through the email chain, a previous version of this patch added 
> ~0.6% to planning time in the worst case tested - does that meet the 
> "essentially free" requirement?
I think these tests weren't full coverage of possible use cases. It will 
depend on a number of relations in the query. For the JOIN of 
partitioned tables, for example, the overhead could grow. But in the 
context of overall planning time this overhead will be small till the 
large number of relations.
Also, we made this feature optional to solve possible problems.
Rebased on 768ea9bcf9

-- 
regards,
Andrey Lepikhov
Postgres Professional