Re: Optimization in convert_string_datum?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Magnus Hagander <magnus(at)hagander(dot)net>
Cc: PGSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Optimization in convert_string_datum?
Date: 2007-05-02 21:28:39
Message-ID: 21504.1178141319@sss.pgh.pa.us
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Magnus Hagander <magnus(at)hagander(dot)net> writes:
> I'm reviewing the strxfrm patch, and while comparing that code to the
> code in varstr_cmp (which uses the same UTF8/UTF16 workaround but for
> strcoll instead), and I noticed that in varstr_cmp we have an
> optimization to use a stack based buffer instead of palloc if the string
> is short enough. Is convert_string_datum performance-critical enough to
> make it worthwhile to put a similar optimization there?

No, I don't believe so. It should only get invoked a few times per
query at most, since only the planner uses it.

It would be far more useful to figure out a way to make that code
actually do something sane with multibyte encodings than to
micro-optimize what's there.

regards, tom lane

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