Postgres 14

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create schema old ;
create schema new ;
create table old.test(id serial primary key, data text) ;
create table new.test_duplicates (id integer primary key, data text) ;

insert into old.test (data) values ('a'),('b'),('c'),('d'),('e');

5 rows affected

CREATE OR REPLACE PROCEDURE duplicates_suppress
(my_target_schema text, my_source_schema text, my_source_table text, unique_keys text[])
LANGUAGE plpgsql AS
$$
BEGIN

EXECUTE FORMAT(
'WITH list AS (INSERT INTO %1$I.%3$I_duplicates SELECT * FROM %2$I.%3$I WHERE array[id] <@ %4$L :: integer[] RETURNING id)
DELETE FROM %2$I.%3$I AS t USING list AS l WHERE t.id = l.id', my_target_schema, my_source_schema, my_source_table, unique_keys :: text) ;

END ;
$$ ;
call duplicates_suppress('new','old','test', '{2,3}' :: text[])
SELECT * FROM old.test


id
data


1
a

4
d

5
e


SELECT * FROM new.test_duplicates


id
data


2
b

3
c