Re: strange explain in upstream - subplan 1 twice - is it bug?

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: strange explain in upstream - subplan 1 twice - is it bug?
Date: 2016-07-07 19:57:05
Message-ID: CA+Tgmob=vjYTFe5NDa5nHRUapSb51e7AYY3evWUnGNayMr6sQQ@mail.gmail.com
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On Wed, Jun 1, 2016 at 7:29 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)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

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