Re: Removing unneeded self joins

From: Andrey Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>
To: Hywel Carver <hywel(at)skillerwhale(dot)com>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Removing unneeded self joins
Date: 2021-07-15 14:49:11
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

On 6/7/21 13:49, Hywel Carver wrote:
> On Mon, Jul 5, 2021 at 2:20 PM Andrey Lepikhov
> <a(dot)lepikhov(at)postgrespro(dot)ru <mailto:a(dot)lepikhov(at)postgrespro(dot)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

Andrey Lepikhov
Postgres Professional

Attachment Content-Type Size
v28-0001-Remove-self-joins.patch text/plain 62.9 KB

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message Ronan Dunklau 2021-07-15 14:53:29 Re: [PATCH] Use optimized single-datum tuplesort in ExecSort
Previous Message Justin Pryzby 2021-07-15 14:47:37 Re: What are exactly bootstrap processes, auxiliary processes, standalone backends, normal backends(user sessions)?