Question

Hey guys, trying to optimize this query to solve a duplicate user issue:

SELECT userid, 'ismaster' AS name, 'false' AS propvalue FROM user 
WHERE userid NOT IN (SELECT userid FROM userprop WHERE name = 'ismaster');

The problem is that the select after the NOT IN is 120.000 records and it’s taking forever.

Using the explain prefix as suggested in the comments returns:

                                    QUERY PLAN

--------------------------------------------------------------------------------
--
 Seq Scan on user  (cost=5559.38..122738966.99 rows=61597 width=8)
   Filter: (NOT (SubPlan 1))
   SubPlan 1
     ->  Materialize  (cost=5559.38..7248.33 rows=121395 width=8)
           ->  Seq Scan on userprop  (cost=0.00..4962.99 rows=121395 width=8
)
                 Filter: ((name)::text = 'ismaster'::text)
(6 rows)

Any suggestion?

Answer 1

Did you put index on userid?

Or try another variation:

SELECT userid, 'ismaster' AS name, 'false' AS propvalue FROM user 
WHERE NOT EXISTS 
 (SELECT * FROM userprop 
 WHERE userpop.userid = user.userid 
   AND name = 'ismaster');