I installed postgres and it used the default postgres directory. Since then I have run out of diskspace on it and need to move it to a new table space. So I did something like:

CREATE TABLESPACE ...
ALTER DATABASE SET TABLESPACE...

The database is about 1.2GB and the ALTER DATABASE ran in like 10 seconds. So I want to know if there is a way to confirm that the data is actually being read from that new tablespace. I see that the size of the directory in the new tablespace is 1.2GB which is correct, but the data still exists in the old directory too.

Is there a way to clean that up?