I've found it already too, but not post back!
Thanks!
2010/12/8 Tom Lane <tgl@xxxxxxxxxxxxx>
> SELECT oid FROM pg_type WHERE typtype = 'b' AND typarray <> 0 ANDSeems like the hard way --- if you think carefully about what regtype
> typname::regtype = 'integer';
is doing, you'll realize that this is incredibly inefficient, as well
as a lot of typing. ÂI usually do SELECT 'integer'::regtype::oid
when I need a quick numeric lookup.
           Âregards, tom lane
--
// Dmitriy.