PostgreSQL code optimalization - sql

Question

I have this code:
SELECT
rv_storage.m_product_id AS n_product_id,
rv_storage.value,
rv_storage.name,
m_warehouse.name AS warehouse_name,
rv_storage.qtyonhand,
rv_transaction.m_transaction_id,
CASE WHEN rv_transaction.movementtype = 'V+' THEN movementdate
ELSE NULL END AS last_in,
CASE WHEN rv_transaction.movementtype = 'C-' THEN movementdate
ELSE NULL END AS last_out,
rv_transaction.movementagedays,
CASE WHEN (movementagedays < -90) AND (movementagedays >= -180) THEN qtyonhand
ELSE NULL END AS more_than_90,
CASE WHEN movementagedays < -180 THEN qtyonhand
ELSE NULL END AS more_than_180
FROM
adempiere.rv_storage
INNER JOIN
adempiere.rv_transaction ON
rv_transaction.m_product_id = rv_storage.m_product_id
AND rv_transaction.movementagedays = (
SELECT MAX(movementagedays)
FROM adempiere.rv_transaction
WHERE
rv_transaction.m_product_id = rv_storage.m_product_id
AND rv_transaction.movementtype = 'C-'
OR rv_transaction.movementtype = 'V+'
)
INNER JOIN
adempiere.m_warehouse ON
m_warehouse.m_warehouse_id = rv_storage.m_warehouse_id
WHERE rv_storage.m_product_id IN (
SELECT m_product_id
FROM adempiere.rv_transaction
WHERE movementagedays < -90
)
ORDER BY n_product_id;
That results in following table:
table http://img9.imageshack.us/img9/4506/table3n.png
But on the server with live data (100k+ rows on each table ) it is too slow.
Can somebody tell me how can the code be optimized?
Thank You

Answer 1

The subquery in the where clause is redundant. And I think you are missing a parenthesis in the where clause of the subquery in the inner join:
SELECT
rv_storage.m_product_id AS n_product_id,
rv_storage.value,
rv_storage.name,
m_warehouse.name AS warehouse_name,
rv_storage.qtyonhand,
rv_transaction.m_transaction_id,
CASE WHEN rv_transaction.movementtype = 'V+' THEN movementdate
ELSE NULL END AS last_in,
CASE WHEN rv_transaction.movementtype = 'C-' THEN movementdate
ELSE NULL END AS last_out,
rv_transaction.movementagedays,
CASE WHEN (movementagedays < -90) AND (movementagedays >= -180) THEN qtyonhand
ELSE NULL END AS more_than_90,
CASE WHEN movementagedays < -180 THEN qtyonhand
ELSE NULL END AS more_than_180
FROM
adempiere.rv_storage
INNER JOIN
adempiere.rv_transaction ON
rv_transaction.m_product_id = rv_storage.m_product_id
AND rv_transaction.movementagedays = (
SELECT MAX(movementagedays)
FROM adempiere.rv_transaction
WHERE
rv_transaction.m_product_id = rv_storage.m_product_id
AND (rv_transaction.movementtype = 'C-'
OR rv_transaction.movementtype = 'V+')
)
INNER JOIN
adempiere.m_warehouse ON
m_warehouse.m_warehouse_id = rv_storage.m_warehouse_id
WHERE movementagedays < -90
ORDER BY n_product_id;
Now post the explain output.

Answer 2

IN() and NOT IN() subqueries are poorly optimized:
MySQL executes the subquery as a dependent subquery for each row in the outer query. This is a frequent cause of serious performance problems in MySQL 5.5 and older versions. The query probably should be rewritten as a JOIN or a LEFT OUTER JOIN, respectively.