understanding mysql explain

Question

So, I\'ve never understood the explain of MySQL. I understand the gross concepts that you should have at least one entry in the possible_keys column for it to u

Answer 1

You query seems to process (244 * 298 * 152) = 11,052,224 records, which according to Using temporary; Using filesort need to be sorted.

This can take long.

If you post your query here, we probably will be able to optimize it somehow.

Update:

You query indeed does a number of nested loops and seems to yield lots of values which need to be sorted then.

Could you please run the following query:

SELECT  COUNT(*)
FROM    `yourock_achievement`
INNER JOIN
        `yourock_achiever`
ON       `yourock_achievement`.`id` = `yourock_achiever`.`achievement_id`
INNER JOIN
        `yourock_alias`
ON      `yourock_achiever`.`alias_id` = `yourock_alias`.`id`
INNER JOIN
        `yourock_achiever` T4
ON      `yourock_alias`.`id` = T4.`alias_id`
INNER JOIN
        `yourock_achievement` T5
ON      T4.`achievement_id` = T5.`id`
INNER JOIN
        `yourock_achiever` T6
ON      T5.`id` = T6.`achievement_id`
WHERE
        T6.`alias_id` = 6