I don't seem to be able to create tables (persistent or temporary) from
within a PL/PGSQL function. With the following script, I can create the
function fine:

CREATE FUNCTION tst()
RETURNS INTEGER
AS '
BEGIN
CREATE TABLE ttt(a int);
RETURN 0;
END;
'
LANGUAGE 'plpgsql';

... but when I execute it , I get the following error. The error happens
regardless of whether I use CREATE TABLE or CREATE TEMPORARY TABLE:

t1=> \i tst.sql
DROP
CREATE
t1=> select tst();
ERROR: copyObject: don't know how to copy 611

Is it somehow wrong to create tables from within a PL/PGSQL function?

Incidently, is it possible to generate a guaranteed unique table name while
creating tables, much like some UNICES' ability to generate guaranteed
unique file names for tempoary files?

Thanks.