On Sat, Jan 17, 2015 at 02:03:34PM +0100, Andreas Kretschmer wrote: > Peter Hicks <peter.hi...@poggs.co.uk> wrote: > > > All, > > > > I have a Rails application on 9.3 in which I want to enforce a unique > > index on a set of fields, one of which includes a NULL-able column. > > > > According to > > http://www.postgresql.org/docs/9.3/static/indexes-unique.html, btree > > indexes can't handle uniqueness on NULL columns, so I'm looking for > > another way to achieve what I need. > > > somethink like that? : > > test=# create table peter_hicks (id int); > CREATE TABLE > Time: 1,129 ms > test=*# create unique index idx_1 on peter_hicks ((case when id is null > then 'NULL' else '' end)) where id is null; > CREATE INDEX > Time: 14,803 ms
Note: COALESCE is probably the better choice here. Have a nice day, -- Martijn van Oosterhout <klep...@svana.org> http://svana.org/kleptog/ > He who writes carelessly confesses thereby at the very outset that he does > not attach much importance to his own thoughts. -- Arthur Schopenhauer
signature.asc
Description: Digital signature
