case and accent insensitive

[MOISES ESPINOSA]

Hi,

I need to reproduced the following Oracle functionality in PostgreSQL:

CREATE INDEX index_ciudad ON world.ciudad
((NLSSORT(NOMBRE29,'nls_sort=''GENERIC_BASELETTER''')));

I don't know how i could reproduced case insensitive and accent insensitive.

Is there any collate?

Thanks.