When the locially dropped column is also physically dropped

Hi,<br />I have dropped a column (say column name is 'A') from the relation R. By setting the attisdropped as true in
thepg_catalog.pg_attribute table. But the column is dropped locially not the physically. Can you please tell me when
thiscolumn will be physically also dropped. Is this column is automatically physically dropped? or I have to run some
commandto dropped it physically. <br /><br />Thanks,<br />Rupesh Bajaj<br />