Re: citext on exclude using gist

Jean Carlo Giambastiani Lopes <jean.lopes@hotmail.com.br> writes:
> I'm trying to use a citext column in the following manner without success:

> create extension btree_gist;
> create extension citext;
> create table my_table(
>     foo citext,
>     bar numrange,
>     primary key (foo, bar),
>     exclude using gist (foo with =, bar with &&)
> );

> is this possible? If so, what's wrong on this snippet?

btree_gist knows nothing of citext, so it's not providing any suitable
operator class.

(Code-wise it probably wouldn't be that hard to add, but I see no good way
to deal with the inter-extension connection other than to give btree_gist
a hard dependency on citext, which people wouldn't appreciate too much.)

You could fake it with

    exclude using gist (lower(foo) with =, bar with &&)

which is surely conceptually ugly, but I think it gives compatible
semantics.

            regards, tom lane