Copy Bulk Ignore Duplicated

Hi,

I have a scenario with a large table and I'm trying to insert it via a
COPY command with a csv file.

Everything works, but sometimes my source .csv file has duplicated data
in the previously fulfilled table. If I add a check constraint and try to
run the COPY command I have an error that stops the whole insertion.

I've tried to put the data in a tmp table and fill the main using
distinct this way (the fields and names are just examples):

INSERT INTO final_table values (name, document)
SELECT DISTINCT name, document
FROM tmp_TABLE t1
WHERE NOT EXISTS (
SELECT 1 FROM final_table t2
WHERE (t2.name, t2.document)
IS NOT DISTINCT FROM (t1.name, t1.document))

The problem is that my final_table is a large (and partitioned) table and
this query is taking a long time to execute.

Someone have any idea (really guys anything would be great) how to solve
this situation? I need to ignore duplicates instead to have some error.

I'm using* PostgreSQL 9.4* so I can't use "ON CONFLICT" and upgrade is not
an option.

Thanks and Kind Regards!

Leandro Guimarães