0
votes
3answers
45 views

Performance first low, then high after adding index, then keep high after drop index

I am testing performance a complicated select query. It is very slow. using explain, I have found a ALL in type COLUMN. Then I ADD INDEX. result comes out fast. However, when I DROP the INDEX I ...
2
votes
2answers
72 views

I need help optimizing a not that complicated query that returns unexpedcted performance problems

I have a table that stores details about incoming and outgoing phone calls such as when a call was made, or when a call was received, the phone number of the caller, and the phone number of the ...
2
votes
1answer
42 views

Making MySQL use primary index without hinting or forcing

I have the following db structure: CREATE TABLE `question` ( `id` int(11) NOT NULL AUTO_INCREMENT, `level_id` int(11) NOT NULL, `video_id` int(11) NOT NULL, `is_active` tinyint(1) NOT NULL, ...
1
vote
1answer
105 views

Best Indexing Strategy for Query with Equality[A], Range[B], Group By[C], AND Order By[count(P)]

I have a poorly performing query: SELECT user_id, count(item_id) as count FROM table items WHERE category = 'magazine' AND created_at > 1384754400 GROUP BY user_id ORDER BY count(item_id) desc ...
2
votes
3answers
286 views

mariadb ignoring force index

I'm trying to tune a relatively simple query: select bt.col1,bt.col2 from bigtable bt join smalltable st on bt.smalltable_id = st.smalltable_id where st.name = 'some name occuring only once in st' ...