> We have a schemas instead - the PostgreSQL schema is close to Oracle
> packages.
Yes, a schema is a kind of a "namespace"-level package. Pg also has 
extensions, which is a group things put together, which may also 
contribute to packaging.
> What we cannot to substitute are package variables, now - see my proposal
> for session variables.
I would like also to point out here that Pg has dynamic text session 
variables with a horrible syntax, aka user-defined GUCs. They can be the 
basis for more useful variables if extended with privacy/some access 
control, typing, better syntax, possibly some kind of persistent 
declarations, and so on.
> [...]
Good luck with your migration...
-- 
Fabien.