From: | Dmitry Dolgov <9erthalion6(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: type cache for concat functions |
Date: | 2017-06-17 22:50:50 |
Message-ID: | CA+q6zcX9=zD1-edrAni_4HXPL-PbjYDeYFdxD2-CEojdr0Pq9Q@mail.gmail.com |
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Thread: | |
Lists: | pgsql-hackers |
> On 20 May 2017 at 10:03, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>
> Now concat is 2x times slower than || operator. With cached FmgrInfo for
> output function it will be only 5%.
Looks nice and does what's expected (what else one may need from a Saturday
evening). I just can mention that from what I see the previous version of
`concat` is slower the more arguments are getting involved, so looks like it
can be more than 2x.
Also, it was a little bit confusing to see that the function `concat`
behaves
differently from operator `||` in terms of performance. When you're looking
at
the code it's becoming obvious, but I couldn't find any mention about that
in
the documentation.
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