From: | James Robinson <jlrobins(at)socialserve(dot)com> |
---|---|
To: | pgsql-sql(at)postgresql(dot)org |
Subject: | Index to enforce non-overlapping ranges? |
Date: | 2008-05-08 13:27:52 |
Message-ID: | 69830892-65A1-49DD-B638-5D6A7F6F3F5B@socialserve.com |
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Thread: | |
Lists: | pgsql-sql |
Academic question here:
Given a table with a pair of any sort of line-segment-esqe range
delimiter columns, is it possible to build a unique index to enforce
non-overlapping ranges? Such as:
create table test
(
id int not null primary key,
low_value int not null,
high_value int not null
);
Can one build an index to enforce a rule such that no (low_value,
high_value) range is identical or overlaps with another (low_value,
high_value) range described by the table? And, more interestingly,
what about for ranges of dates / timestamps as opposed to simple
integers?
I can see how a trigger on insert or update could enforce such a
constraint [ probe the table for an existing overlapping row, and
raise exception one exists ], but can such an activity be performed
with fewer lines using some sort of r-tree index?
----
James Robinson
Socialserve.com
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