Re: BUG #14525: select <function>.* takes extremely long time

Hi

2017-02-02 10:05 GMT+01:00 <martin(dot)langwisch(at)gmx(dot)net>:

> The following bug has been logged on the website:
>
> Bug reference: 14525
> Logged by: Martin Langwisch
> Email address: martin(dot)langwisch(at)gmx(dot)net
> PostgreSQL version: 9.6.1
> Operating system: openSUSE 11.4 (x86_64)
> Description:
>
> I have a function f that returns a composite type.
> The following query:
> select f().*
> takes about ten times as long as either
> select f()
> or
> select (f).* from (select f() as f) a;
>
> It doesn't matter whether the function returns a composite type or a set of
> composite type.
>
> This behaviour strikes me as odd, to say the least and it took me quite
> some
> time to find out why my code was so slow.
>

Although it looks strange - it is expected behave - and it is not a bug

XT is a composite type (a, b, c)

fx is a function with XT result.

SELECT (fx()).* is translated by parser to query SELECT fx().a, fx().b,
fx().c ....

When your function fx is slow, then you cannot to use a (fx()).* pattern

Regards

Pavel

>
> yours
> Martin
>
>
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