Question

I have this query which is taking around 40-50 seconds to load

SELECT
  members.latitude,
  members.longitude,
  members.mem_id
FROM members
WHERE profile_type != "C"
    AND (gender = 'm'
          OR gender = 'f')
    AND members.mem_id IN(SELECT DISTINCT
                            n2.mem_id
                          FROM network n1,
                            network n2
                          WHERE n1.frd_id = n2.mem_id
                              AND n1.mem_id = '48'
                              AND n2.frd_id = '48')
ORDER BY profilenam

there is network table which contains users friends

Please help..

Answer 1

this is slow because of the sub-query used try it without sub-query using derived table:

SELECT latitude, longitude, a.mem_id
FROM members a
     INNER JOIN (SELECT DISTINCT n2.mem_id AS mem_id
                 FROM network n1,
                      network n2
                 WHERE n1.frd_id = n2.mem_id
                       AND n1.mem_id = '48'
                       AND n2.frd_id = '48'
                ) b
                ON a.mem_id = b.mem_id
WHERE profile_type != "C"
      AND (gender = 'm'
           OR gender = 'f')
ORDER BY profilenam;

Also add proper indexes on table and use EXPLAIN EXTENDED to check for index usage:

ALTER TABLE network ADD KEY ix1(mem_id);
ALTER TABLE network ADD KEY ix1(frd_id);