| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Greg Stark <gsstark(at)mit(dot)edu> |
| Cc: | David Fetter <david(at)fetter(dot)org>, Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: WIP: generalized index constraints |
| Date: | 2009-07-06 17:20:06 |
| Message-ID: | 1246900806.28986.79.camel@jdavis |
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| Lists: | pgsql-hackers |
On Mon, 2009-07-06 at 17:02 +0100, Greg Stark wrote:
> On Mon, Jul 6, 2009 at 4:57 PM, Jeff Davis<pgsql(at)j-davis(dot)com> wrote:
> >
> > Exactly, you already know my use case ;) My goal is a "temporal key",
> > where you can't have overlapping intervals of time, e.g. the constraint
> > "nobody can be two places at the same time".
>
> Incidentally to handle non-overlapping ranges you don't need GIST, you
> can actually use a plain btree. Since there are no overlapping ranges
> the ranges have a complete ordering and you can get that by just
> sorting by either endpoint. To enforce the constraint you only have to
> compare with the previous and following element in the btree.
What if you have an entire index full of overlapping dead tuples, and a
few live ones? How would search work?
Regards,
Jeff Davis
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