script causing cpu max limit - get_audiences_list()

[gilby]

Having just had this problem myself
I have found out a couple of relavent things

It appears that that the check for NULL on a field used in the joins is a lot faster.
Also a few versions of mysql had problems testing for NULL on fields not used in the joins.

So a first improvement is to replace the o.date_purchased field with o.customers_id field

SELECT DISTINCT c.customers_email_address as customers_email_address, c.customers_lastname as customers_lastname, c.customers_firstname as customers_firstname FROM TABLE_CUSTOMERS c LEFT JOIN  TABLE_ORDERS o ON c.customers_id=o.customers_id WHERE o.customers_id IS NULL

An altenative that you can try that seems to produce around the same times is

SELECT DISTINCT c.customers_email_address as customers_email_address, c.customers_lastname as customers_lastname, c.customers_firstname as customers_firstname FROM TABLE_CUSTOMERS c 
WHERE c.customers_id NOT IN 
(
SELECT o.customers_id AS customers_id
FROM TABLE_ORDERS o
)

Both of these improved my selection times considerably

Obviously backup before trying either of these to see if they work for you