Re: [HACKERS] LIKE fixed(?) for non-ASCII collation orders

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От Andreas Degert
Тема Re: [HACKERS] LIKE fixed(?) for non-ASCII collation orders
Дата
Msg-id 87vh5fgnvq.fsf@tarzan.noname.
обсуждение исходный текст
Ответ на LIKE fixed(?) for non-ASCII collation orders  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: [HACKERS] LIKE fixed(?) for non-ASCII collation orders  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: [HACKERS] LIKE fixed(?) for non-ASCII collation orders  (Bruce Momjian <pgman@candle.pha.pa.us>)
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Tom Lane <tgl@sss.pgh.pa.us> writes:

> I have just committed what I hope is the final solution for the problem
> of LIKE index optimization in non-ASCII locales.  indxpath.c now
> generates both a lower and upper indexqual in all locales.  For example,
>     x LIKE 'foo%t'
> will create indexqual conditions
>     x >= 'foo' AND x < 'fop'
> The "<" condition is omitted only if the code is unable to produce a
> string greater than the pattern's constant prefix.

the .. >= .. < .. condition will result in addtional matches, like 'fo ot',
so you still have to check with LIKE. I'm using such an expression
(without the additional LIKE) in an application, and it seems to match 
at least everything that LIKE would match too (my users would have
complained about missing matches, but i never did a formal test or
evaluation).


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