Mysql - help me optimize this query
- by sandeepan-nath
About the system:
-The system has a total of 8 tables
- Users
- Tutor_Details (Tutors are a type of User,Tutor_Details table is linked to Users)
- learning_packs, (stores packs created by tutors)
- learning_packs_tag_relations, (holds tag relations meant for search)
- tutors_tag_relations and tags and
orders (containing purchase details of tutor's packs),
order_details linked to orders and tutor_details.
For a more clear idea about the tables involved please check the The tables section in the end.
-A tags based search approach is being followed.Tag relations are created when new tutors register and when tutors create packs (this makes tutors and packs searcheable). For details please check the section How tags work in this system? below.
Following is a simpler representation (not the actual) of the more complex query which I am trying to optimize:- I have used statements like explanation of parts in the query
select SUM(DISTINCT( t.tag LIKE "%Dictatorship%" )) as key_1_total_matches,
SUM(DISTINCT( t.tag LIKE "%democracy%" )) as key_2_total_matches,
td., u., count(distinct(od.id_od)), if (lp.id_lp > 0) then some conditional logic on lp fields else 0 as tutor_popularity
from Tutor_Details AS td JOIN Users as u on u.id_user = td.id_user
LEFT JOIN Learning_Packs_Tag_Relations AS lptagrels ON td.id_tutor = lptagrels.id_tutor
LEFT JOIN Learning_Packs AS lp ON lptagrels.id_lp = lp.id_lp
LEFT JOIN `some other tables on lp.id_lp - let's call learning pack tables set (including
Learning_Packs table)`
LEFT JOIN Order_Details as od on td.id_tutor = od.id_author LEFT JOIN Orders as o on
od.id_order = o.id_order
LEFT JOIN Tutors_Tag_Relations as ttagrels ON td.id_tutor = ttagrels.id_tutor
JOIN Tags as t on (t.id_tag = ttagrels.id_tag) OR (t.id_tag = lptagrels.id_tag)
where some condition on Users table's fields
AND CASE WHEN ((t.id_tag = lptagrels.id_tag) AND (lp.id_lp 0)) THEN `some
conditions on learning pack tables set` ELSE 1 END
AND CASE WHEN ((t.id_tag = wtagrels.id_tag) AND (wc.id_wc 0)) THEN `some
conditions on webclasses tables set` ELSE 1 END
AND CASE WHEN (od.id_od0) THEN od.id_author = td.id_tutor and some conditions on Orders table's fields ELSE 1 END
AND ( t.tag LIKE "%Dictatorship%" OR t.tag LIKE "%democracy%")
group by td.id_tutor HAVING key_1_total_matches = 1 AND key_2_total_matches = 1
order by tutor_popularity desc, u.surname asc, u.name asc limit
0,20
=====================================================================
What does the above query do?
Does AND logic search on the search keywords (2 in this example - "Democracy" and "Dictatorship").
Returns only those tutors for which both the keywords are present in the union of the two sets - tutors details and details of all the packs created by a tutor.
To make things clear - Suppose a Tutor name "Sandeepan Nath" has created a pack "My first pack", then:-
Searching "Sandeepan Nath" returns Sandeepan Nath.
Searching "Sandeepan first" returns Sandeepan Nath.
Searching "Sandeepan second" does not return Sandeepan Nath.
======================================================================================
The problem
The results returned by the above query are correct (AND logic working as per expectation), but the time taken by the query on heavily loaded databases is like 25 seconds as against normal query timings of the order of 0.005 - 0.0002 seconds, which makes it totally unusable.
It is possible that some of the delay is being caused because all the possible fields have not yet been indexed, but I would appreciate a better query as a solution, optimized as much as possible, displaying the same results
==========================================================================================
How tags work in this system?
When a tutor registers, tags are entered and tag relations are created with respect to tutor's details like name, surname etc.
When a Tutors create packs, again tags are entered and tag relations are created with respect to pack's details like pack name, description etc.
tag relations for tutors stored in tutors_tag_relations and those for packs stored in learning_packs_tag_relations. All individual tags are stored in tags table.
====================================================================
The tables
Most of the following tables contain many other fields which I have omitted here.
CREATE TABLE IF NOT EXISTS users (
id_user int(10) unsigned NOT NULL AUTO_INCREMENT,
name varchar(100) NOT NULL DEFAULT '',
surname varchar(155) NOT NULL DEFAULT '',
PRIMARY KEY (id_user)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=636 ;
CREATE TABLE IF NOT EXISTS tutor_details (
id_tutor int(10) NOT NULL AUTO_INCREMENT,
id_user int(10) NOT NULL DEFAULT '0',
PRIMARY KEY (id_tutor),
KEY Users_FKIndex1 (id_user)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=51 ;
CREATE TABLE IF NOT EXISTS orders (
id_order int(10) unsigned NOT NULL AUTO_INCREMENT,
PRIMARY KEY (id_order),
KEY Orders_FKIndex1 (id_user),
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=275 ;
ALTER TABLE orders
ADD CONSTRAINT Orders_ibfk_1 FOREIGN KEY (id_user) REFERENCES users
(id_user) ON DELETE NO ACTION ON UPDATE NO ACTION;
CREATE TABLE IF NOT EXISTS order_details (
id_od int(10) unsigned NOT NULL AUTO_INCREMENT,
id_order int(10) unsigned NOT NULL DEFAULT '0',
id_author int(10) NOT NULL DEFAULT '0',
PRIMARY KEY (id_od),
KEY Order_Details_FKIndex1 (id_order)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=284 ;
ALTER TABLE order_details
ADD CONSTRAINT Order_Details_ibfk_1 FOREIGN KEY (id_order) REFERENCES orders
(id_order) ON DELETE NO ACTION ON UPDATE NO ACTION;
CREATE TABLE IF NOT EXISTS learning_packs (
id_lp int(10) unsigned NOT NULL AUTO_INCREMENT,
id_author int(10) unsigned NOT NULL DEFAULT '0',
PRIMARY KEY (id_lp),
KEY Learning_Packs_FKIndex2 (id_author),
KEY id_lp (id_lp)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=23 ;
CREATE TABLE IF NOT EXISTS tags (
id_tag int(10) unsigned NOT NULL AUTO_INCREMENT,
tag varchar(255) DEFAULT NULL,
PRIMARY KEY (id_tag),
UNIQUE KEY tag (tag),
KEY id_tag (id_tag),
KEY tag_2 (tag),
KEY tag_3 (tag)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=3419 ;
CREATE TABLE IF NOT EXISTS tutors_tag_relations (
id_tag int(10) unsigned NOT NULL DEFAULT '0',
id_tutor int(10) DEFAULT NULL,
KEY Tutors_Tag_Relations (id_tag),
KEY id_tutor (id_tutor),
KEY id_tag (id_tag)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
ALTER TABLE tutors_tag_relations
ADD CONSTRAINT Tutors_Tag_Relations_ibfk_1 FOREIGN KEY (id_tag) REFERENCES
tags (id_tag) ON DELETE NO ACTION ON UPDATE NO ACTION;
CREATE TABLE IF NOT EXISTS learning_packs_tag_relations (
id_tag int(10) unsigned NOT NULL DEFAULT '0',
id_tutor int(10) DEFAULT NULL,
id_lp int(10) unsigned DEFAULT NULL,
KEY Learning_Packs_Tag_Relations_FKIndex1 (id_tag),
KEY id_lp (id_lp),
KEY id_tag (id_tag)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
ALTER TABLE learning_packs_tag_relations
ADD CONSTRAINT Learning_Packs_Tag_Relations_ibfk_1 FOREIGN KEY (id_tag)
REFERENCES tags (id_tag) ON DELETE NO ACTION ON UPDATE NO ACTION;
===================================================================================
Following is the exact query (this includes classes also - tutors can create classes and search terms are matched with classes created by tutors):-
select count(distinct(od.id_od)) as tutor_popularity, CASE WHEN (IF((wc.id_wc 0), ( wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date '2010-06-01 22:00:56' AND wccp.status = 1 AND (wccp.country_code='IE' or wccp.country_code IN ('INT'))), 0)) THEN 1 ELSE 0 END as 'classes_published', CASE WHEN (IF((lp.id_lp 0), (lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND (lpcp.country_code='IE' or lpcp.country_code IN ('INT'))),0)) THEN 1 ELSE 0 END as 'packs_published', td . * , u . * from Tutor_Details AS td JOIN Users as u on u.id_user = td.id_user LEFT JOIN Learning_Packs_Tag_Relations AS lptagrels ON td.id_tutor = lptagrels.id_tutor LEFT JOIN Learning_Packs AS lp ON lptagrels.id_lp = lp.id_lp LEFT JOIN Learning_Packs_Categories AS lpc ON lpc.id_lp_cat = lp.id_lp_cat LEFT JOIN Learning_Packs_Categories AS lpcp ON lpcp.id_lp_cat = lpc.id_parent LEFT JOIN Learning_Pack_Content as lpct on (lp.id_lp = lpct.id_lp) LEFT JOIN Webclasses_Tag_Relations AS wtagrels ON td.id_tutor = wtagrels.id_tutor LEFT JOIN WebClasses AS wc ON wtagrels.id_wc = wc.id_wc LEFT JOIN Learning_Packs_Categories AS wcc ON wcc.id_lp_cat = wc.id_wp_cat LEFT JOIN Learning_Packs_Categories AS wccp ON wccp.id_lp_cat = wcc.id_parent LEFT JOIN Order_Details as od on td.id_tutor = od.id_author LEFT JOIN Orders as o on od.id_order = o.id_order LEFT JOIN Tutors_Tag_Relations as ttagrels ON td.id_tutor = ttagrels.id_tutor JOIN Tags as t on (t.id_tag = ttagrels.id_tag) OR (t.id_tag = lptagrels.id_tag) OR (t.id_tag = wtagrels.id_tag) where (u.country='IE' or u.country IN ('INT')) AND CASE WHEN ((t.id_tag = lptagrels.id_tag) AND (lp.id_lp 0)) THEN lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND (lpcp.country_code='IE' or lpcp.country_code IN ('INT')) ELSE 1 END AND CASE WHEN ((t.id_tag = wtagrels.id_tag) AND (wc.id_wc 0)) THEN wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date '2010-06-01 22:00:56' AND wccp.status = 1 AND (wccp.country_code='IE' or wccp.country_code IN ('INT')) ELSE 1 END AND CASE WHEN (od.id_od0) THEN od.id_author = td.id_tutor and o.order_status = 'paid' and CASE WHEN (od.id_wc 0) THEN od.can_attend_class=1 ELSE 1 END ELSE 1 END AND 1 group by td.id_tutor order by tutor_popularity desc, u.surname asc, u.name asc limit 0,20
Please note - The provided database structure does not show all the fields and tables as in this query
