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I see SELECT EXISTS used a lot like: if db.query(""" SELECT EXISTS ( SELECT 1 FROM checkout WHERE checkout_id = %s ) """ % checkout_id).getresult()[0][0] == 't': vs. what i prefer: if db.query(""" SELECT 1 FROM checkout WHERE checkout_id = %s LIMIT 1 """ % checkout_id).getresult(): Which one is preferred and why? P.S. i am using Python and PosgreSQL. cert=> explain SELECT EXISTS (SELECT 1 FROM checkout WHERE checkout_id = 3); QUERY PLAN -------------------------------------------------------------------------------------- Result (cost=4.03..4.03 rows=1 width=0) InitPlan -> Index Scan using checkout_pkey on checkout (cost=0.00..4.03 rows=1 width=0) Index Cond: (checkout_id = 3) (4 rows) cert=> explain SELECT 1 FROM checkout WHERE checkout_id = 3 limit 1; QUERY PLAN ------------------------------------------------------------------------------------ Limit (cost=0.00..4.03 rows=1 width=0) -> Index Scan using checkout_pkey on checkout (cost=0.00..4.03 rows=1 width=0) Index Cond: (checkout_id = 3) (3 rows) My point is, why getting a row from the result and check if it's first column is true, if i can just check if there are any rows at all, meaning the same?

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