RE: Progress report on locale safe LIKE indexing

> -----Original Message-----
> From: Peter Eisentraut
>
> Hiroshi Inoue writes:
>
> > Please look at my first question.
> >    This depends on the assumption that '=' is equivalent in
> >    any locale. Is it guaranteed ?
> >    For example, ( 'a' = 'A' ) isn't allowed in any locale ?.
> >
> > And your answer was
> >    The whole point here is not to rely on '='.
> >
> > Clearly your theory depends on the assumption that
> >    If a = b in some locale then a = b in ASCII locale.
> >
> > And where does 'a' <> 'A' come from ?
> > The definition of '=' is a part of collating sequence.
> >
> > >
> > > > LIKE seems to use the collating sequence.
> > >
> > > No.  The collating sequence defines the order of all possible strings.
> > > LIKE doesn't order anything.
> >
> > Again where does it come from ?
>
> Let me elaborate again:
>
> Now, if you look at the code that does the LIKE pattern matching you'll
> see that it does not use any locale features, it simply compares
> characters for equality based on their character codes, accounting for the
> wildcards.  Consequentially, this whole operation has nothing to do with
> locales.

Oh I see your point.
Hmm  * string1 = string2 * doesn't imply * string1 LIKE string2 * ?

Otherwise the current criterion of LIKE matching unwittingly assumes
that there's no locale that has the different definition of '=' from that of
ASCII locale.  I don't think the current implementation is strictly right.

regards,
Hiroshi Inoue