select sum(score) total,name,gender,dob,country from users join scores on users.id = scores.user_id where date between '2012-01-01' and '2012-01-31 23:59:59' group by scores.user_id having sum(score)>=1000 order by sum(score) desc limit 50
So trying to get a list of accumulated scores for Jan 2012, order them by scores descending and paginate them.
Without limit: slowish but OK: searches 69348 rows. (Be nice to work out how to avoid the temporary table but I can't). Explain says:
1, 'SIMPLE', 'scores', 'range', 'user,date,user+date', 'date', '8', '', 69348, 'Using where; Using temporary; Using filesort' 1, 'SIMPLE', 'users', 'eq_ref', 'PRIMARY', 'PRIMARY', '8', 'scores.user_id', 1, 'Using where'
With limit: it's the same but the rows search are now 1806794 and it takes forever.
It's a partitioned InnoDB if that makes any difference, with all data being on one partition.