remove duplicate records in postgres where all records are duplicate - postgresql

Question

My postgres table model have exactly duplicate record, I need to write a query to delete them.
id | model | model_id | dependent_on_model
-----+-------+----------+--------------------
1 | Card | 72 | Metric
1 | Card | 72 | Metric
2 | Card | 79 | Metric
2 | Card | 79 | Metric
3 | Card | 83 | Metric
3 | Card | 83 | Metric
5 | Card | 86 | Metric
using Cte is not helping as i am getting the error
relation "cte" does not exist.
Please suggest a query which delete the duplicate row and i will have just 4 distinct records at the end.

Answer 1

My suggestion is to duplicate the table in a TEMPORARY TABLE WITH OIDS. This way you have some other id to distinguish the two identical rows.
Idea:
Duplicate the data with another ID in a temporary table.
Remove duplicates in temporary table.
Delete actual table
Copy data back into actual table from temporary table.
Delete the TEMPORARY TABLE
You'll have to perform some destructive action on your actual table so make sure your TEMPORARY TABLE has what you want remaining before deleting anything from your actual table.
This is how you would create the TEMPORARY TABLE:
CREATE TEMPORARY TABLE dups_with_oids
( id integer
, model text
, model_id integer
, dependent_on_model text
) WITH OIDS;
Here is the DELETE query:
WITH temp AS
(
SELECT d.id AS keep
, d.oid AS keep_oid
, d2.id AS del
, d2.oid AS del_oid
FROM dups_with_oids d
JOIN dups_with_oids d2 ON (d.id = d2.id AND d.oid < d2.oid)
)
DELETE FROM dups_with_oids d
WHERE d.oid IN (SELECT temp.del_oid FROM temp);
SQLFiddle to prove the theory.
I should add that if id were a PRIMARY KEY or UNIQUE these duplicates wouldn't have been possible.