Re: WIP: generalized index constraints

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>
To: Peter Eisentraut <peter_e@gmx.net>
Cc: Jeff Davis <pgsql@j-davis.com>, Brendan Jurd <direvus@gmail.com>, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, pgsql-hackers@postgresql.org
Date: 2009-09-16T17:54:33Z
Lists: pgsql-hackers
On Wed, Sep 16, 2009 at 3:14 AM, Peter Eisentraut <peter_e@gmx.net> wrote:
> On Tue, 2009-09-15 at 12:37 -0400, Robert Haas wrote:
>> Instead of calling these generalized index constraints, I wonder if we
>> oughtn't to be calling them something like "don't-overlap constraints"
>> (that's a bad name, but something along those lines).  They're not
>> really general at all, except compared to uniqueness constraints (and
>> they aren't called generalized unique-index constraints, just
>> generalized index constraints).
>
> What they should be called is generalized unique constraints, without
> reference to "index".  Because what they generalize is the operator by
> which uniqueness is determined.

Well, it should eventually be possible to use this feature to create
an index which excludes overlapping ranges  in fact, unless I
misunderstand, that's the principle likely use case.  Which is not
unique-ness at all.

...Robert