Optimizing a simple query with many left joins - mysql

Question

I have quite a large query which is used for a user search on 'map_item'.
SELECT map_item_name
FROM map_item
LEFT JOIN map_section_item ON map_section_item_item_id = map_item_id
LEFT JOIN map_section ON map_section_id = map_section_item_section_id
LEFT JOIN map_item_flag ON map_item_flag_item_id = map_item_id
LEFT JOIN flag ON flag_id = map_item_flag_flag_id
LEFT JOIN map ON map_id = map_section_map_id
LEFT JOIN place_map ON place_map_map_id = map_id
LEFT JOIN place ON place_id = place_map_place_id
LEFT JOIN place_category ON place_category_place_id = place_id
LEFT JOIN category ON category_id = place_category_category_id
LEFT JOIN review ON review_map_item_id = map_item_id
LEFT JOIN map_price ON map_price_item_id = map_item_id
LEFT JOIN county_list ON place_address_county = county_id
'map_item' has 5399 records in total and none of the joined tables have much data in at all.
If I run this query without the left joins (SELECT map_item_name FROM map_item) it returns in 0.00s as expected, but the above query with the joins takes around 10.00s.
All of the left joins are required in the query due to the different filters that the user can apply to the search, however the original query was taking a long time to run (20 seconds or so), and after stripping out most parts of the query I was left with the above (which is just the left joins) and even this is taking 18 seconds to run.
Here is the explain statement from the query:
+----+-------------+-------------------+--------+----------------------------------+----------------------------------+---------+-----------------------------------------------------------+------+-----------------------------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------------------+--------+----------------------------------+----------------------------------+---------+-----------------------------------------------------------+------+-----------------------------------------------------------------+
| 1 | SIMPLE | map_item | ALL | NULL | NULL | NULL | NULL | 5455 | NULL |
| 1 | SIMPLE | map_section_item | index | NULL | map_section_item_section_id | 8 | NULL | 5330 | Using where; Using index; Using join buffer (Block Nested Loop) |
| 1 | SIMPLE | map_section | eq_ref | PRIMARY | PRIMARY | 4 | bestmeal.map_section_item.map_section_item_section_id | 1 | NULL |
| 1 | SIMPLE | map_item_flag | ALL | NULL | NULL | NULL | NULL | 1509 | Using where; Using join buffer (Block Nested Loop) |
| 1 | SIMPLE | flag | eq_ref | PRIMARY | PRIMARY | 4 | bestmeal.map_item_flag.map_item_flag_flag_id | 1 | Using index |
| 1 | SIMPLE | map | eq_ref | PRIMARY | PRIMARY | 4 | bestmeal.map_section.map_section_map_id | 1 | Using index |
| 1 | SIMPLE | place_map | index | NULL | branch_map_branch_id | 8 | NULL | 1275 | Using where; Using index; Using join buffer (Block Nested Loop) |
| 1 | SIMPLE | place | eq_ref | PRIMARY | PRIMARY | 4 | bestmeal.place_map.place_map_place_id | 1 | NULL |
| 1 | SIMPLE | place_category | ref | place_category_place_id | place_category_place_id | 4 | bestmeal.place.place_id | 1 | Using index |
| 1 | SIMPLE | category | eq_ref | PRIMARY | PRIMARY | 4 | bestmeal.place_category.place_category_category_id | 1 | Using index |
| 1 | SIMPLE | review | ref | review_map_item_id | review_map_item_id | 4 | bestmeal.map_item.map_item_id | 1 | Using index |
| 1 | SIMPLE | map_price | ref | map_price_item_id | map_price_item_id | 4 | bestmeal.map_item.map_item_id | 1 | Using index |
| 1 | SIMPLE | county_list | eq_ref | PRIMARY | PRIMARY | 4 | bestmeal.place.place_address_county | 1 | Using index |
+----+-------------+-------------------+--------+----------------------------------+----------------------------------+---------+-----------------------------------------------------------+------+-----------------------------------------------------------------+
All of these joins are made against indexed fields, and none of the tables that are joined have any unnecessary indexes in them which could be used instead of the intended index.
I'm not an expert when it comes to optimising queries, but I'm struggling to work out what I can do to speed this query up whilst keeping the left joins. I also can't really think of any alternative solutions which will return the same results without using the joins.
Does anybody have any ideas that will help me to increase the performance on this query or accomplish the user search using a different, faster method?
Edit
Table structures as requested:
CREATE TABLE `map_item` (
`map_item_id` int(11) NOT NULL AUTO_INCREMENT,
`map_item_account_id` int(11) NOT NULL DEFAULT '0',
`map_item_category_id` int(11) NOT NULL,
`map_item_name` varchar(255) DEFAULT NULL,
`map_item_description` text,
`map_item_tags` varchar(255) DEFAULT NULL,
`map_item_type` set('d','f') DEFAULT NULL,
PRIMARY KEY (`map_item_id`),
KEY `map_item_account_id` (`map_item_account_id`),
KEY `map_item_tags` (`map_item_tags`),
KEY `map_item_category_id` (`map_item_category_id`),
FULLTEXT KEY `map_item_keyword_search` (`map_item_name`,`map_item_description`,`map_item_tags`),
FULLTEXT KEY `map_item_name` (`map_item_name`),
FULLTEXT KEY `map_item_description` (`map_item_description`),
FULLTEXT KEY `map_item_tags_2` (`map_item_tags`)
) ENGINE=InnoDB AUTO_INCREMENT=5420 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `map_section_item` (
`map_section_item_id` int(11) NOT NULL AUTO_INCREMENT,
`map_section_item_section_id` int(11) NOT NULL DEFAULT '0',
`map_section_item_item_id` int(11) NOT NULL DEFAULT '0',
PRIMARY KEY (`map_section_item_id`),
KEY `map_section_item_section_id` (`map_section_item_section_id`,`map_section_item_item_id`)
) ENGINE=InnoDB AUTO_INCREMENT=24410 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `map_section` (
`map_section_id` int(11) NOT NULL AUTO_INCREMENT,
`map_section_map_id` int(11) NOT NULL DEFAULT '0',
`map_section_map_draft_id` int(11) NOT NULL DEFAULT '0',
`map_section_column` tinyint(1) NOT NULL DEFAULT '1',
`map_section_name` varchar(255) DEFAULT NULL,
`map_section_description` text,
PRIMARY KEY (`map_section_id`),
KEY `map_section_map_draft_id` (`map_section_map_draft_id`),
KEY `map_section_map_id` (`map_section_map_id`),
FULLTEXT KEY `index_name` (`map_section_name`)
) ENGINE=InnoDB AUTO_INCREMENT=4254 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `map_item_flag` (
`map_item_flag_id` int(11) NOT NULL AUTO_INCREMENT,
`map_item_flag_item_id` int(11) NOT NULL DEFAULT '0',
`map_item_flag_flag_id` int(11) NOT NULL DEFAULT '0',
PRIMARY KEY (`map_item_flag_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1547 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `flag` (
`flag_id` int(11) NOT NULL AUTO_INCREMENT,
`flag_category_id` int(11) NOT NULL DEFAULT '0',
`flag_name` varchar(255) DEFAULT NULL,
`flag_description` varchar(255) DEFAULT NULL,
`flag_img` varchar(255) DEFAULT NULL,
`flag_order` tinyint(2) NOT NULL DEFAULT '0',
PRIMARY KEY (`flag_id`),
KEY `flag_category_id` (`flag_category_id`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `map` (
`map_id` int(11) NOT NULL AUTO_INCREMENT,
`map_account_id` int(11) NOT NULL DEFAULT '0',
`map_name` varchar(255) DEFAULT NULL,
`map_description` text,
`map_type` set('d','f') DEFAULT NULL,
`map_layout` set('columns','tabs','collapsed') DEFAULT NULL,
PRIMARY KEY (`map_id`),
KEY `map_account_id` (`map_account_id`)
) ENGINE=InnoDB AUTO_INCREMENT=138 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `place_map` (
`place_map_id` int(11) NOT NULL AUTO_INCREMENT,
`place_map_place_id` int(11) NOT NULL DEFAULT '0',
`place_map_map_id` int(11) NOT NULL DEFAULT '0',
`place_map_active` tinyint(1) NOT NULL DEFAULT '0',
PRIMARY KEY (`place_map_id`),
KEY `branch_map_branch_id` (`place_map_place_id`,`place_map_map_id`)
) ENGINE=InnoDB AUTO_INCREMENT=2176 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `place` (
`place_id` int(11) NOT NULL AUTO_INCREMENT,
`place_account_id` int(11) NOT NULL DEFAULT '0',
`place_name` varchar(120) DEFAULT NULL,
`place_alias` varchar(255) DEFAULT NULL,
`place_description` text,
`place_address_line_one` varchar(100) DEFAULT NULL,
`place_address_line_two` varchar(100) DEFAULT NULL,
`place_address_line_three` varchar(100) DEFAULT NULL,
`place_address_town` varchar(100) DEFAULT NULL,
`place_address_county` int(11) NOT NULL DEFAULT '0',
`place_address_postcode` varchar(10) DEFAULT NULL,
`place_address_latitude` decimal(11,8) DEFAULT NULL,
`place_address_longitude` decimal(11,8) DEFAULT NULL,
`place_phone` varchar(20) DEFAULT NULL,
`place_email` varchar(255) DEFAULT NULL,
`place_website` varchar(120) DEFAULT NULL,
`place_flag_initial_email` tinyint(1) NOT NULL DEFAULT '0',
`place_audit_admin_id` int(11) NOT NULL DEFAULT '0',
`place_last_audit_datetime` datetime DEFAULT NULL,
`place_created_by_admin_id` int(11) NOT NULL DEFAULT '0',
`place_created` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
`place_tried_google` int(1) NOT NULL DEFAULT '0',
PRIMARY KEY (`place_id`),
KEY `place_account_id` (`place_account_id`),
KEY `place_address_county` (`place_address_county`),
KEY `place_alias` (`place_alias`),
KEY `place_audit_admin_id` (`place_audit_admin_id`),
KEY `place_created_by_admin_id` (`place_created_by_admin_id`),
FULLTEXT KEY `place_name` (`place_name`),
FULLTEXT KEY `place_keyword_search` (`place_name`,`place_address_town`),
FULLTEXT KEY `place_address_town` (`place_address_town`)
) ENGINE=InnoDB AUTO_INCREMENT=135167 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `place_category` (
`place_category_id` int(11) NOT NULL AUTO_INCREMENT,
`place_category_place_id` int(11) NOT NULL DEFAULT '0',
`place_category_category_id` int(11) NOT NULL DEFAULT '0',
PRIMARY KEY (`place_category_id`),
UNIQUE KEY `place_category_place_id` (`place_category_place_id`,`place_category_category_id`)
) ENGINE=InnoDB AUTO_INCREMENT=208987 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `category` (
`category_id` int(11) NOT NULL AUTO_INCREMENT,
`category_name` varchar(255) DEFAULT NULL,
PRIMARY KEY (`category_id`)
) ENGINE=InnoDB AUTO_INCREMENT=168 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `review` (
`review_id` int(11) NOT NULL AUTO_INCREMENT,
`review_user_id` int(11) NOT NULL DEFAULT '0',
`review_place_id` int(11) NOT NULL DEFAULT '0',
`review_map_item_id` int(11) NOT NULL DEFAULT '0',
`review_otm_item_name` varchar(156) DEFAULT NULL,
`review_headline` varchar(255) DEFAULT NULL,
`review_message` text,
`review_rating` tinyint(1) NOT NULL DEFAULT '0',
`review_datetime` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
`review_edited_datetime` datetime DEFAULT NULL,
`review_hidden` tinyint(1) NOT NULL DEFAULT '0',
`review_deleted` tinyint(1) NOT NULL DEFAULT '0',
`review_status` set('pending','published','hidden','deleted') NOT NULL,
PRIMARY KEY (`review_id`),
KEY `review_map_item_id` (`review_map_item_id`),
KEY `review_place_id` (`review_place_id`),
KEY `review_user_id` (`review_user_id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `map_price` (
`map_price_id` int(11) NOT NULL AUTO_INCREMENT,
`map_price_item_id` int(11) NOT NULL DEFAULT '0',
`map_price_label` varchar(50) DEFAULT NULL,
`map_price_value` decimal(10,2) DEFAULT NULL,
PRIMARY KEY (`map_price_id`),
KEY `map_price_item_id` (`map_price_item_id`)
) ENGINE=InnoDB AUTO_INCREMENT=5872 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT
CREATE TABLE `county_list` (
`county_id` int(11) NOT NULL AUTO_INCREMENT,
`county_country_id` int(11) NOT NULL DEFAULT '0',
`county_name` varchar(120) DEFAULT NULL,
`county_alias` varchar(120) DEFAULT NULL,
PRIMARY KEY (`county_id`),
KEY `county_alias` (`county_alias`),
KEY `county_country_id` (`county_country_id`)
) ENGINE=InnoDB AUTO_INCREMENT=142 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT

Answer 1

Look at these lines:
LEFT JOIN map_section_item ON map_section_item_item_id = map_item_id
| 1 | SIMPLE | map_section_item | index | NULL | map_section_item_section_id | 8 | NULL | 5330 | Using where; Using index; Using join buffer (Block Nested Loop) |
|
Notice "5330". That means it had to search about 5330 items to find the row it needed.
With a simple INDEX(map_section_item_item_id), it would go directly to the one (or few) row it needed. This would make the query run a lot faster.
Repeat for each other JOIN, at least for those with a "Rows" > 1.
Why LEFT? Is each "right" table optionally missing data?
A side issue: Don't prefix everything with the table name; it is too much clutter.

Answer 2

For MySQL, try using the STRAIGHT_JOIN clause...
SELECT STRAIGHT_JOIN map_item_name
FROM map_item
LEFT JOIN ...
STRAIGHT_JOIN tells MySQL to do the query in the order I've listed. This way it forces the map_item as the primary table and all the rest as lookup secondary tables...