As a general rule, avoid heavy subselects like that. You don't need to build a full list of duplicates before starting. Another approach:
create table mytable2 (like mytable1); alter table mytable2 add primary key (id); insert into mytable2 select * from mytable1 on conflict do nothing; Given the size of your table, you probably want to divide that up. As long as nothing is changing the original table, you could do: insert into mytable2 select * from mytable1 order by ctid limit 10_000_000 offset 0; insert into mytable2 select * from mytable1 order by ctid limit 10_000_000 offset 10_000_000; insert into mytable2 select * from mytable1 order by ctid limit 10_000_000 offset 20_000_000; etc. Cheers, Greg
