Re: strange explain in upstream - subplan 1 twice - is it bug? - Mailing list pgsql-hackers

From Robert Haas
Subject Re: strange explain in upstream - subplan 1 twice - is it bug?
Date
Msg-id CA+Tgmob=vjYTFe5NDa5nHRUapSb51e7AYY3evWUnGNayMr6sQQ@mail.gmail.com
Whole thread Raw
In response to strange explain in upstream - subplan 1 twice - is it bug?  (Pavel Stehule <pavel.stehule@gmail.com>)
Responses Re: strange explain in upstream - subplan 1 twice - is it bug?  (Pavel Stehule <pavel.stehule@gmail.com>)
Re: strange explain in upstream - subplan 1 twice - is it bug?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Wed, Jun 1, 2016 at 7:29 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
> Hi
>
> When I tested some queries, I found strange plan
>
> postgres=# explain analyze select s.nazev, o.nazev, o.pocet_obyvatel from
> (select nazev, array(select id from obce_pocet_obyvatel where okresy.id =
> okres_id order by pocet_obyvatel desc limit 3) as obceids from okresy) s
> join obce_pocet_obyvatel o on o.id = ANY(obceids) order by 1, 3 desc;

The EXPLAIN plan you posted certainly looks weird, since I wouldn't
expect SubPlan 1 to be displayed twice, but I'm wondering if it's a
display artifact rather than an actual defect in the plan.

Just out of curiosity, what does the output look like with FORMAT JSON
or similar?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company



pgsql-hackers by date:

Previous
From: Pete Stevenson
Date:
Subject: Re: MVCC overheads
Next
From: Robert Haas
Date:
Subject: Re: A Modest Upgrade Proposal