Re: Query for block updates

Amit Shah <ashah@opuspro.com> writes:
> I am using this query - alter table optiondata ALTER volume TYPE numeric(20,4) 
> using cast(volume as numeric(20,4)); then wait for DB to complain, and then 
> update that value to null, and just keep doing this till all garbadge is 
> removed :-(

You could automate it in plpgsql ... something like
for r in select id, val from tableloop    begin        perform cast(r.val as numeric(20,4));    exception        when
...then            update table set val = null where id = r.id;    end;end loop;
 

and then do the ALTER TYPE after you've cleaned the data.
        regards, tom lane