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I have 2 tables (A and B) with the same primary keys. I want to select all row that are in A and not in B. The following works:
select * from A where not exists (select * from B where A.pk=B.pk); however it seems quite bad (~2 sec on only 100k rows in A and 3-10k less in B)
Is there a better way to run this? Perhaps as a left join?
select * from A left join B on A.x=B.y where B.y is null; On my data this seems to run slightly faster (~10%) but what about in general?
I use queries in the format of your second example. A join is usually more scalable than a correlated subquery.