Gerhard Heift <ml-postgresql-20081012-3518@xxxxxxxxx> writes: > I try to create an unique index for a (time)period, and my goal is to > prevent two overlapping periods in a row. > To use the btree index I added a compare function: > return > CASE > WHEN $1.next <= $2.first THEN -1 > WHEN $2.next <= $1.first THEN 1 > ELSE 0 > END; This does not work as a btree compare function, because it fails to satisfy the basic requirements of a total order. In particular it doesn't satisfy the transitive law that A=B and B=C must imply A=C. I don't believe it is possible to use a btree index for this purpose, because there just isn't a way to express "overlaps" as a total order. It'd be really nice to have uniqueness support in gist indexes someday ... regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
