Re: Collation versioning

From: Stephen Frost <sfrost(at)snowman(dot)net>
To: Douglas Doole <dougdoole(at)gmail(dot)com>
Cc: Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Christoph Berg <myon(at)debian(dot)org>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Collation versioning
Date: 2018-09-18 22:09:31
Message-ID: 20180918220931.GS4184@tamriel.snowman.net
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Greetings,

* Douglas Doole (dougdoole(at)gmail(dot)com) wrote:
> > The CHECK constraint doesn't need to directly track that information-
> > it should have a dependency on the column in the table and that's where
> > the information would be recorded about the current collation version.
>
> Just to have fun throwing odd cases out, how would something like this be
> recorded?
>
> Database default collation: en_US
>
> CREATE TABLE t (c1 TEXT, c2 TEXT, c3 TEXT,
> CHECK (c1 COLLATE "fr_FR" BETWEEN c2 COLLATE "fr_FR" AND c3 COLLATE
> "fr_FR"));
>
> You could even be really warped and apply multiple collations on a single
> column in a single constraint.

Once it gets to an expression and not just a simple check, I'd think
we'd record it in the expression..

Thanks!

Stephen

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