Re: PATCH: CITEXT 2.0

From: "David E(dot) Wheeler" <david(at)kineticode(dot)com>
To: Gregory Stark <stark(at)enterprisedb(dot)com>
Cc: <pgsql-hackers(at)postgresql(dot)org>, "Zdenek Kotala" <Zdenek(dot)Kotala(at)Sun(dot)COM>, "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>
Subject: Re: PATCH: CITEXT 2.0
Date: 2008-07-07 21:05:24
Message-ID: BAC3302A-D88F-49C9-9E7D-596C347D9649@kineticode.com
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On Jul 7, 2008, at 13:59, Gregory Stark wrote:

> Of course the obvious case of two equivalent strings with different
> bytes
> would be two strings which differ only in case in a collation which
> doesn't
> distinguish based on case. So you obviously can't take this route
> for citext.

Well, to be fair, citext isn't imposing a collation. It's just calling
str_tolower() on strings before passing them on to varstr_cmp() or
strncmp() to compare.

> I don't think you have to worry about the problem that cause
> Postgres to make
> this change. IIRC it was someone comparing strings like paths and
> usernames
> and getting false positives because they were in a Turkish locale
> which found
> certain sequences of characters to be insignificant for ordering.
> Someone
> who's using a citext data type has obviously decided that's
> precisely the kind
> of behaviour they want.

Hrm. So in your opinion, strncmp() could be used for all comparisons
by citext, rather than varstr_cmp()?

Thanks,

David

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