On Mon, Jul 24, 2017 at 3:12 PM, Dmitry Lazurkin <dila...@gmail.com> wrote:
> And I have one question. I don't understand why IN-VALUES doesn't use > Semi-Join? PostgreSQL has Hash Semi-Join... For which task the database > has node of this type? > ​Semi-Join is canonically written as: SELECT * FROM tbl WHERE EXISTS (SELECT 1 FROM tbl2 WHERE tbl.id = tbl2.id) The main difference between IN and EXISTS is NULL semantics. David J.
