Re: Delete performance

Phillip Sitbon <phillip(at)sitbon(dot)net> writes:
> I've had to do this quite a bit, and here's how I usually go about it:

> DELETE FROM data_structures_items WHERE NOT EXISTS
> (SELECT 1 FROM data_structures WHERE id_structure=id_data_structure LIMIT 1);

> Even when the item in the subquery is a primary key, I find it
> semantically informative to always use "LIMIT 1".

EXISTS implies LIMIT 1 for its subquery; there's no value for either
comprehension or performance in adding that. I'd recommend leaving
it off, because it makes your query syntax nonstandard for no benefit.

regards, tom lane