abnormal size of the on-disk file.

Hi There,

I have a small table companies (< 300 rows) and its on-disk size shows

abnormal

i check it as follows:

SELECT relname,relfilenode from pg_class where relfilenode=30977;
relname | relfilenode
-----------+-------------
companies | 30977
(1 row)

ls -lsh 30977
487M -rw------- 1 postgres postgres 486M Apr 26 20:27 30977
bash-2.03$

i created a new table with the same content

tradein_clients=> CREATE TABLE t_a as select * from companies;

SELECT

its on disk file is very small

tradein_clients=> SELECT relname,relfilenode from pg_class where
relname='t_a';
relname | relfilenode
---------+-------------
t_a | 87812505
(1 row)

bash-2.03$ ls -lsh 87812505
196k -rw------- 1 postgres postgres 192k Apr 26 20:27 87812505
bash-2.03$

Can anyone explain this ..

does unvaccuming makes tables x2000 times largers??

regds
mallah.