vacuuming - doubt

[Jayadevan M <maymala.jayadevan@xxxxxxxxx>]

Hi,

Another theory question -

PostgreSQL documentation says that -
"There are two variants of VACUUM: standard VACUUM and VACUUM FULL. VACUUM FULL can reclaim more disk space "

I created a table, inserted 1000 records and deleted them. The size after a vacuum and a vacuum full are given -
select pg_total_relation_size('myt');;
 pg_total_relation_size
------------------------
                  65536
(1 row)

accounts=> vacuum   myt;
VACUUM

accounts=> select pg_total_relation_size('myt');;
 pg_total_relation_size
------------------------
                  16384
(1 row)

accounts=> vacuum  full myt;
VACUUM
accounts=> select pg_total_relation_size('myt');;
 pg_total_relation_size
------------------------
                      0
(1 row)

So what was the 65536 bytes left behind after standard vacuum?

Regards,

Jayadevan