Re: explain with costs in subselect.sql

From: Andres Freund <andres(at)anarazel(dot)de>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: explain with costs in subselect.sql
Date: 2018-03-12 22:28:07
Message-ID: 20180312222807.4jud5mlpj7aac5n7@alap3.anarazel.de
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On 2018-03-12 18:25:42 -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > When forcing JITing to be enabled for all queries, obviously only useful
> > for testing, I noticed that two explain outputs changed after I added
> > explain support.
>
> > The only differences come from:
>
> > -- Unspecified-type literals in output columns should resolve as text
>
> > SELECT *, pg_typeof(f1) FROM
> > (SELECT 'foo' AS f1 FROM generate_series(1,3)) ss ORDER BY 1;
>
> > -- ... unless there's context to suggest differently
>
> > explain verbose select '42' union all select '43';
> > explain verbose select '42' union all select 43;
>
> > which don't use costs=off. Is there a reason for that? I assume it was
> > just a harmless oversight?
>
> Duh, yeah, explain (verbose, costs off) would do fine there.
> Mea culpa. Do you want to fix it?

Yup, will do.

Random aside: Noticed that we have *no* proper coverage of AND / OR
behaviour of returning NULL if no element returns true. Will push
something to add coverage, I've now manually retested that twice for
JITing, which seems stupid.

Greetings,

Andres Freund

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