How to optimize MySQL multiple tables select queries? - mysql

Question

My MySQL query code likes as shown below, and there are about several thousands of records in the table, by now below SQL executes about 5 minutes and more. I am looking for ways to optimize it so that it takes less time to execute. Thank you!
SELECT `m`.`id`,
`m`.`id`,
`tr`.`name`,
`m`.`m_date`,
`t1`.`t_name` AS home,
`t2`.`t_name` AS away,
`m`.`score1`,
`m`.`score2`,
`cw1`.`tid` AS tid1,
`cw2`.`tid` AS tid2,
`o1`.`odds` AS odds1,
`o2`.`odds` AS odds2,
`m`.`m_time`
FROM `jos_bl_match` AS `m`
LEFT JOIN `jos_bl_matchday` AS `md` ON (`md`.`id` = `m`.`m_id`)
LEFT JOIN `jos_bl_seasons` AS `s` ON (`s`.`s_id` = `md`.`s_id`)
LEFT JOIN `jos_bl_tournament` AS `tr` ON (`tr`.`id` = `s`.`t_id`)
LEFT JOIN `jos_bl_teams` AS `t1` ON (`m`.`team1_id` = `t1`.`id`)
LEFT JOIN `jos_bl_teams` AS `t2` ON (`m`.`team2_id` = `t2`.`id`)
LEFT JOIN `jos_vuvuzelaodds_odds` AS `o1` ON (`o1`.`m_id` = `m`.`id`)
AND `o1`.`market_id` = 1
AND `o1`.`bookmaker_id` = 1
LEFT JOIN `jos_vuvuzelaodds_odds` AS `o2` ON (`o2`.`m_id` = `m`.`id`)
AND `o2`.`market_id` = 1
AND `o2`.`bookmaker_id` = 2
LEFT JOIN `jos_cwtags_tags` AS `cw1` ON (`cw1`.`item_id` = `o1`.`m_id`)
LEFT JOIN `jos_cwtags_tags` AS `cw2` ON (`cw2`.`item_id` = `o2`.`m_id`)
WHERE `m`.`published` = 1
AND `s`.`published` = '1'
AND `tr`.`published` = '1'
AND `s`.`s_id` = 869
AND `m`.`m_played` = '1'
AND `m`.`m_date` > 2013-01-01
AND `o1`.`odds` != ''
AND `o2`.`odds` != ''
AND `cw1`.`cat_id` = 19
AND `cw2`.`cat_id` = 21
ORDER BY `m`.`m_date`,
`md`.`id`,
`s`.`s_id`,
`tr`.`id` DESC LIMIT 0, 15

Answer 1

"Normalize, but don't over-normalize."
Some composite indexes you may be missing...
jos_bl_match: INDEX(m_played, published, m_date)
The columns need to be in that order. That will more quickly start the filtering.
The following should speed up their JOINs:
jos_vuvuzelaodds_odds: INDEX(market_id, bookmaker_id, m_id)
jos_cwtags_tags: INDEX(cat_id, item_id)
It seems like those last two indexes could (should) be the PRIMARY KEY. Are they?
Some (perhaps all) of the LEFT JOINs may as well be INNER JOINs; did you consider that?
Please provide EXPLAIN SELECT.

Answer 2

Without having access to the database it is a little hard to tell. This seems to be a lot of data to only pull 15 records. Are you sure you need to pull the data this way?
Probably the best route:
Optimize your database as below.
Make a flat database view of all the games that has the fields that you need. A static table will be much faster but you would need to set up updates with triggers which is beyond the scope of this answer but the process is similar
Write queries against the
view.
You are not selecting any fields from the seasons table in your select. I used the field from the jos_bl_matchday table.
This should get you started. You can also use conditionals in your select statements
(IF value = 1, table.field, null) as yadda
instead of joining one table over and over again but you would have to experiment.
CREATE VIEW allTheGames AS SELECT
`m`.`id` as id,
`md`.`s_id` as seasonId,
`tr`.`name` as name,
`m`.`m_date` as m_date,
`t1`.`t_name` AS home,
`t2`.`t_name` AS away,
`m`.`score1` as score1,
`m`.`score2` as score2,
`cw1`.`tid` AS tid1,
`cw2`.`tid` AS tid2,
`o1`.`odds` AS odds1,
`o2`.`odds` AS odds2,
`m`.`m_time` as m_time
FROM `jos_bl_match` AS `m`
LEFT JOIN `jos_bl_matchday` AS `md` ON (`md`.`id` = `m`.`m_id`)
LEFT JOIN `jos_bl_tournament` AS `tr` ON (`tr`.`id` = `s`.`t_id`)
LEFT JOIN `jos_bl_teams` AS `t1` ON (`m`.`team1_id` = `t1`.`id`)
LEFT JOIN `jos_bl_teams` AS `t2` ON (`m`.`team2_id` = `t2`.`id`)
LEFT JOIN `jos_vuvuzelaodds_odds` AS `o1` ON (`o1`.`m_id` = `m`.`id`) AND `o1`.`market_id` = 1 AND `o1`.`bookmaker_id` = 1
LEFT JOIN `jos_vuvuzelaodds_odds` AS `o2` ON (`o2`.`m_id` = `m`.`id`) AND `o2`.`market_id` = 1 AND `o2`.`bookmaker_id` = 2
LEFT JOIN `jos_cwtags_tags` AS `cw1` ON (`cw1`.`item_id` = `o1`.`m_id`)
LEFT JOIN `jos_cwtags_tags` AS `cw2` ON (`cw2`.`item_id` = `o2`.`m_id`)
WHERE `m`.`published` = 1 AND `s`.`published` = '1' AND `tr`.`published` = '1'
AND `m`.`m_played` = '1'
AND `o1`.`odds1` != '' AND `o2`.`odds2` != ''
Then query it with:
select * from allTheGames
WHERE season_id = 869 AND m_date > 2013-01-01 AND tid1 = 19 AND tid2 = 21
Steps to optimize:
Figure out exactly which data you want out of this query and why:
Is this a custom report? A web page? do you need to have all of this data at once or would it make more sense to have the user drill down?
How often is the query run? Once a minute? Once a day?
How many records are in each table? Your view should reflect this "game object"
Your database:
Run "explain" against this query http://dev.mysql.com/doc/refman/5.7/en/explain.html.
It will show all of the work the database is doing, the query execution plan, and how many records it is looking in to do it. This usually happens quickly: it does not actually execute the query.
See if you can put the database on SSD drives or even RAM
Your table structure:
Make sure that you have indexes on all of the fields that you are searching on. There are many ways to optimize this.
Use "explain" to be sure MySQL is able to use indexes.
If there are really only 2 markets in the jos_vuvuzelaodds_odds table consider making 2 fields.
Good luck!