Need suggestion on how best to update 3 million rows

I have a table in PG, Pulled from SQL Server using Perl DBI (w/o using
chopblanks) and have ended up with a column where the "space" is being
interpreted as a value.

eg:

"ABC " when it should be "ABC"

this is being defined  as varchar(4)

I've already pull the relevent columns with

create foo as select unique_id, rtrim(number) from org_column

I've tried to do the update using

update org_column set number = foo.number where foo.unique_id =
org_column=unique_id.

The update is taking a few hours and still hasn't ended.

I've killed it already and rolled back the changes.

what's the easiest way to update these fields?


Thanks..