RE: Progress report on locale safe LIKE indexing

From: "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp>
To: "Peter Eisentraut" <peter_e(at)gmx(dot)net>
Cc: "PostgreSQL Development" <pgsql-hackers(at)postgresql(dot)org>
Subject: RE: Progress report on locale safe LIKE indexing
Date: 2001-08-18 15:56:50
Message-ID: EKEJJICOHDIEMGPNIFIJGEJFFCAA.Inoue@tpf.co.jp
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> -----Original Message-----
> From: Peter Eisentraut [mailto:peter_e(at)gmx(dot)net]
>
> Hiroshi Inoue writes:
>
> > > An operator class text_binary_ops that does memcmp()-based
> comparison of
> > > text data. The operators are named $<$ etc. for lack of a
> better idea.
> > > That lack is further illustrated by the idea to name them
> "binary-<" etc.,
> > > which wouldn't get through the parser, but it doesn't need to.
> > >
> > > The system will use such an index for the queries in question if the
> > > locale is not "like-safe", in the terminology of the code (I'll end up
> > > renaming that a little).
> >
> > This depends on the assumption that '=' is equivalent in
> > any locale. Is it guaranteed ?
> > For example, ( 'a' = 'A' ) isn't allowed in any locale ?
>
> The whole point here is not to rely on '='. Instead we use a different
> opclass which does "locale-safe" comparisons, as said above.

Isn't 'a' LIKE 'A' if 'a' = 'A' ?
LIKE seems to use the collating sequence.

regards,
Hiroshi Inoue

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