Removing duplicate records from a bulk upload

I have just completed the bulk upload of a large database. Some tables have billions of records and no constraints or indexes have been applied yet. About 0.1% of these records may have been duplicated during the upload and I need to remove them before applying constraints.

I understand there are (at least) two approaches to get a table without duplicate records…

- Delete duplicate records from the table based on an appropriate select clause;

- Create a new table with the results from a select distinct clause, and then drop the original table.

What would be the most efficient procedure in PostgreSQL to do the job considering …

- I do not know which records were duplicated;

- There are no indexes applied on tables yet;

- There is no OIDS on tables yet;

- The database is currently 1TB but I have plenty of disk space.

Daniel