Determine length of numeric field

I'm altering datatypes in several tables from numeric to integer. In
doing so, I get the following error:

dw=# \d uniq_hits
Table "support.uniq_hits"
Column | Type | Modifiers
------------+---------+-----------
sourceid | numeric |
hitdate | date |
total | numeric |
hitdate_id | integer |
Indexes:
"uniq_hits_hitdateid_idx" btree (hitdate_id), tablespace
"support_idx"
Tablespace: "support"

esave_dw=# alter table uniq_hits alter sourceid type int;
ERROR: integer out of range

Sourceid should not be more than 5 digits long. I'm able to perform
this query on Oracle and would like something similar on postgres 8.4:

delete from uniq_hits where sourceid in (select sourceid from uniq_hits
where length(sourceid) > 5);

I haven't had much luck with the length or char_length functions on
postgres.

Thanks.
Tony