How to improve this complex query? - mysql

Question

My query is running very long. I tried to improve the query performance by adding index on website_id in hh_hits table.
Query:
SELECT
w.state, xx.pretty_name, xx.member_id,
SUM(ce.total_charge) as total_charge,
SUM(ce.shipping_cost) as shipping_cost,
SUM(ce.product_price * product_count) as product_price,
SUM(ce.tax) as tax,
SUM(ce.service_charge) as service_charge,
COUNT(distinct ce.order_id) as order_count,
SUM(ce.product_count) as product_count,
SUM( (select sum(addon_price*addon_count)
from wow.cart_entry_addons_archive cean
where cean.cart_entry_id=ce.cart_entry_id
and cean.addon_type='xx'
group by ce.cart_entry_id)) as giftwrap_total,
sum( (select sum(addon_price*addon_count)
from wow.cart_entry_addons_archive cean2
where cean2.cart_entry_id=ce.cart_entry_id
and cean2.addon_type='xx'
group by ce.cart_entry_id)) as addon_total,
(select sum(number) as hits
from wow.hh_hits thts
where thts.website_id=xx.website_id
and thts.start_date >= 'xxx'
and thts.start_date <= 'xx') as visits
FROM
wow.carts_archive c,
wow.cart_entries_archive ce,
eoe.websites xx
WHERE
ce.order_date >= 'xx' and
ce.order_date <= 'xx' and
ce.website_id=xx.website_id and
lower(ce.status) != 'deleted' and
ce.order_status != 'cancelled' and
ce.cart_id = c.cart_id and
(c.cc_number <> '343334' or c.cc_number is null)
GROUP BY ce.website_id
ORDER BY ce.website_id;
Explain plan:
+----+--------------------+-------+--------+------------------+----------+---------+---------------------------+-------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------------+-------+--------+------------------+----------+---------+---------------------------+-------+----------------------------------------------+
| 1 | PRIMARY | ce | range | id1_nn,idx_726 | idx_1049 | 9 | NULL | 33 | Using where; Using filesort |
| 1 | PRIMARY | w | ref | idx_1055 | idx_1055 | 5 | wow.ce.website_id | 1 | Using where |
| 1 | PRIMARY | c | eq_ref | PRIMARY | PRIMARY | 4 | eoe.ce.cart_id | 1 | Using where |
| 4 | DEPENDENT SUBQUERY | thts | ALL | hh_n1 | NULL | NULL | NULL | 24493 | Using where |
| 3 | DEPENDENT SUBQUERY | cean2 | ref | idx_1383 | idx_1383 | 4 | wow.ce.cart_entry_id | 1 | Using where; Using temporary; Using filesort |
| 2 | DEPENDENT SUBQUERY | cean | ref | idx_1383 | idx_1383 | 4 | wow.ce.cart_entry_id | 1 | Using where; Using temporary; Using filesort |
Query explain plan seems hh_hits table is not using indexes.

Answer 1

On hh_hits, add this compound index:
INDEX(website_id, start_date)
For further discussion, please provide SHOW CREATE TABLE for each of the tables.
If my suggestion does not help enough, then we should talk about building a Summary Table that contains the subtotals for each website-date pair. You would augment the table each night, then run the dependent subquery against it.