From: | Alexander Kuzmenkov <a(dot)kuzmenkov(at)postgrespro(dot)ru> |
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To: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: type cache for concat functions |
Date: | 2017-08-24 17:24:50 |
Message-ID: | 748b7a45-b1b0-7a8d-719f-4d42a1645d50@postgrespro.ru |
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Lists: | pgsql-hackers |
Hi Pavel,
I tried applying your patch, it applies and compiles fine, check and
checkworld pass.
I ran a simple performance test, select
concat(generate_series(1,100000), ... [x5 total]) vs select
generate_series(1,100000)::text || ... .
Operator || runs in 60 ms, while unpatched concat takes 90 and patched
-- 55 ms.
About the code:
* There seems to be an extra tab here:
FmgrInfo *typcache;
It's not aligned with the previous declaration with tab size 4.
* You could allocate the cache and store it into the context inside
rebuildConcatCache. It would return return the cache pointer, and the
calling code would look cleaner -- just one line. This is a matter of
taste though.
* The nearby functions use snake_case, so it should be
rebuild_concat_cache too.
Overall the patch looks good to me.
--
Alexander Kuzmenkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
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