Question

My data scheme is really simple, let s say it’s about farms

• tableA is the main one, with an
  important field “is_active” assuming
  the farm is trusted (kind of)
• tableB is a data storage of
  serialized arrays about farms
  statistics

I want to retrieve all data about active farm so I just do something like that:

SELECT * FROM tableA LEFT JOIN tableB ON id_tableA=id_tableB WHERE is_active=1 ORDER BY id_tableA DESC;

Right now the query takes 15 sec to execute straight from a sql shell, for example it I want to retrieve all data from the tableB, like :

 SELECT * FROM tableB ORDER BY id_tableB DESC;

it takes less than 1 sec (approx 1200 rows)…

Any ideas how to improve the original query ?

thx

Answer 1

Create indexes on the keys joing two tables..

check this link, how to create indexes in mysql:
http://dev.mysql.com/doc/refman/5.0/en/create-index.html