DELETE FROM table1 WHERE table2_id = ?

For bulk deletes, try :

DELETE FROM table1 WHERE table2_id IN (list of a few thousands ids)

- or use a JOIN delete with a virtual VALUES table
- or fill a temp table with ids and use a JOIN DELETE

This will save cliet/server roundtrips.

Now, something that can make a DELETE very slow is a non-indexed ON DELETE CASCADE foreign key : when you DELETE FROM table1 and it cascades to a DELETE on table2, and you forget the index on table2. Also check the time spent in triggers. Do you have a GIN index ?

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