Date: Fri, 23 Apr 2004 13:16:15 -0700 (PDT)
From: Stephan Szabo <sszabo@megazone.bigpanda.com>
To: Shachar Shemesh <psql@shemesh.biz>
Cc: Robert Treat <xzilla@users.sourceforge.net>,
	Dennis Bjorklund <db@zigo.dhs.org>, Bruce Momjian <pgman@candle.pha.pa.us>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
	PostgreSQL advocacy <pgsql-advocacy@postgresql.org>
Subject: Re: [HACKERS] What can we learn from MySQL?
In-Reply-To: <40897131.6020902@shemesh.biz>
Message-ID: <20040423130701.K21905@megazone.bigpanda.com>
References: <Pine.LNX.4.44.0404231117270.4551-100000@zigo.dhs.org>
	<1082735128.22969.1106.camel@camel>
	<20040423094236.J17459@megazone.bigpanda.com>
	<40897131.6020902@shemesh.biz>
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On Fri, 23 Apr 2004, Shachar Shemesh wrote:

> Stephan Szabo wrote:
>
> >I've tried just changing the parser to unconditionally casefold to upper.
> >First thing that happens is that initdb breaks. In addition, you have
> >potential issues with comparisons against the catalog's versions of
> >standard functions as such if you allow the case folding to be changed
> >after the catalogs are setup.
> >
> >
> That's not the migration path I was thinking of.
>
> What I was thinking of was:
> 1. Have a setting, probably per-session. Per database works too.
> 2. Aside from the folder upper and folder lower, have a third option.
> This is "fold upper, if fails, fold lower. If succeeds, issue a
> warning". This should allow programs that rely on the folding (such as
> initdb) to be debugged during the transition period.

If you can do this in a clean fashion without tromping all around the
code, that'd be reasonable, however, istm that you'd need to either
pre-fold both directions from the given identifier string and pass an
extra copy around or pass the original identifier and its quoted status
and fold on use.  I think either of these are likely to be very intrusive
for what essentially amounts to a transitional feature.

In addition, I'm not sure that this would always work in any case, since
some of those usages may be quoted identifiers that were once generated
from a case-folded string (for example, looking up a name in the catalogs
and quoting it).