MySQL Long First Query Time - mysql

Question

I have a website that has two main queries to the database which are pretty slow the first time they are run, after a bit of testing it appears to be an issue with MySQL. If I run the query directly in Sequal Pro when I run a query the first time it can take up to 4 seconds to run but running the same query again takes ~60ms, the query time is about the same locally as on our server, which make me think its not a server issue.
Not totally sure that increasing the buffer pool size will help too much as the number of potential query combinations is probably around 800K.
The tables in the database are innodb, both queries access the same table that has 52K records, most of the information I need has been grouped together into a 'searchfield' field which is indexed.
Only fields used in queries or are primary/foreign keys are being indexed.
I have tried changing the inner joins to a select statement in the "where" of the main query but this doesn't make the query any faster.
The queries are
Query 1
SELECT
`item_attribute`.`attribute_id` AS `attribute_id`,
`attribute_value_id` AS `attribute_value_id`,
`collection_attribute`.`title` AS `ca_title`,
`collection_attribute`.`type` AS `ca_type`,
`collection_attribute`.`is_collapsible` AS `ca_is_collapsible`,
`collection_attribute`.`orderindex` AS `ca_orderindex`,
`collection_attribute`.`multi_select` AS `ca_multi_select`,
`item_attribute`.`item_id` AS `item_id`,
`product`.`id` AS `product_id`
FROM `item_attribute`
INNER JOIN `item` ON item.id = item_attribute.item_id
INNER JOIN `product` ON product.id = item.product_id
INNER JOIN `collection_attribute` ON item_attribute.attribute_id = collection_attribute.attribute_id
INNER JOIN `attribute_value` ON attribute_value.id = item_attribute.attribute_value_id
WHERE ((`product`.`searchfilter` LIKE '%c:35∆%') AND (`collection_attribute`.`collection_id`='35')) AND (`attribute_value`.`active`=1)
GROUP BY `attribute_value_id`
Query 2
SELECT DISTINCT `item_attribute`.`attribute_id` AS `attribute_id`,
GROUP_CONCAT(item_attribute.attribute_value_id SEPARATOR \"-\") AS `attribute_value`,
GROUP_CONCAT(attribute_value.title SEPARATOR \" - \") AS `title`
FROM `item_attribute`
LEFT JOIN `item` ON item.id = item_attribute.item_id
LEFT JOIN `attribute` ON attribute.id = item_attribute.attribute_id
LEFT JOIN `attribute_value` ON attribute_value.id = attribute_value_id
WHERE (`item`.`product_id`='894') AND (`attribute`.`is_option`=1)
GROUP BY `attribute_id`, `item_id`
Table Structure
CREATE TABLE `product` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`title` varchar(255) NOT NULL,
`slug` varchar(255) NOT NULL,
`sku` varchar(20) NOT NULL,
`active` tinyint(1) DEFAULT '0',
`orderindex` int(2) DEFAULT '-1',
`search` varchar(255) DEFAULT NULL,
`searchfilter` varchar(255) DEFAULT NULL,
`created_at` int(11) DEFAULT NULL,
`updated_at` int(11) DEFAULT NULL,
`protected` tinyint(1) DEFAULT '0',
`description` varchar(512) DEFAULT NULL,
`type_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `product_ibfk_1` (`type_id`),
KEY `searchfilter` (`searchfilter`),
CONSTRAINT `product_ibfk_1` FOREIGN KEY (`type_id`) REFERENCES `attribute_value` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=1882 DEFAULT CHARSET=utf8;
--
CREATE TABLE `collection_attribute` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`collection_id` int(11) DEFAULT NULL,
`attribute_id` int(11) DEFAULT NULL,
`title` varchar(512) NOT NULL,
`slug` varchar(512) NOT NULL,
`created_at` int(11) DEFAULT NULL,
`updated_at` int(11) DEFAULT NULL,
`active` tinyint(1) DEFAULT '0',
`orderindex` int(2) DEFAULT '-1',
`search` varchar(255) DEFAULT NULL,
`searchfilter` varchar(255) DEFAULT NULL,
`protected` tinyint(1) DEFAULT '0',
`is_collapsible` tinyint(1) DEFAULT '0',
`type` enum('icon','checkbox','checkboxIcon','image') DEFAULT NULL,
`multi_select` tinyint(1) DEFAULT '0',
PRIMARY KEY (`id`),
KEY `collection_attribute_ibfk_1` (`collection_id`),
KEY `collection_attribute_ibfk_2` (`attribute_id`),
CONSTRAINT `collection_attribute_ibfk_1` FOREIGN KEY (`collection_id`) REFERENCES `collection` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `collection_attribute_ibfk_2` FOREIGN KEY (`attribute_id`) REFERENCES `attribute` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=140 DEFAULT CHARSET=utf8;
--
CREATE TABLE `item` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`slug` varchar(255) NOT NULL,
`title` varchar(255) NOT NULL,
`pattern_code` varchar(32) NOT NULL,
`tom_code` varchar(32) NOT NULL,
`navision_code` varchar(32) NOT NULL,
`description` varchar(255) DEFAULT NULL,
`active` tinyint(1) DEFAULT '0',
`orderindex` int(2) DEFAULT '-1',
`created_at` int(11) DEFAULT NULL,
`updated_at` int(11) DEFAULT NULL,
`search` varchar(1024) DEFAULT NULL,
`searchfilter` varchar(255) DEFAULT NULL,
`product_id` int(11) DEFAULT NULL,
`protected` tinyint(1) DEFAULT '0',
`pattern_series` varchar(255) DEFAULT NULL,
`pattern_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `item_ibfk_1` (`product_id`),
KEY `searchfilter` (`searchfilter`),
KEY `product_id` (`product_id`),
KEY `pattern_id` (`pattern_id`),
CONSTRAINT `item_ibfk_1` FOREIGN KEY (`product_id`) REFERENCES `product` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `item_ibfk_2` FOREIGN KEY (`pattern_id`) REFERENCES `pattern_series` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=50060 DEFAULT CHARSET=utf8;
--
CREATE TABLE `item_attribute` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`item_id` int(11) NOT NULL,
`attribute_id` int(11) NOT NULL,
`attribute_value_id` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `attribute_id` (`attribute_id`),
KEY `attribute_value_id` (`attribute_value_id`),
KEY `item_id` (`item_id`),
CONSTRAINT `item_attribute_ibfk_1` FOREIGN KEY (`attribute_id`) REFERENCES `attribute` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `item_attribute_ibfk_2` FOREIGN KEY (`attribute_value_id`) REFERENCES `attribute_value` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `item_attribute_ibfk_3` FOREIGN KEY (`item_id`) REFERENCES `item` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=857111 DEFAULT CHARSET=utf8;
--
CREATE TABLE `attribute_value` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`slug` varchar(255) NOT NULL,
`code` varchar(255) DEFAULT NULL,
`title` varchar(255) NOT NULL,
`active` tinyint(1) DEFAULT '0',
`orderindex` int(2) DEFAULT '-1',
`created_at` int(11) DEFAULT NULL,
`updated_at` int(11) DEFAULT NULL,
`search` varchar(255) DEFAULT NULL,
`searchfilter` varchar(255) DEFAULT NULL,
`attribute_id` int(11) DEFAULT NULL,
`protected` tinyint(1) DEFAULT '0',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3471 DEFAULT CHARSET=utf8;
--
CREATE TABLE `attribute` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`title` varchar(255) NOT NULL,
`slug` varchar(255) NOT NULL,
`code` varchar(255) DEFAULT NULL,
`is_option` tinyint(1) DEFAULT '0',
`searches` tinyint(1) DEFAULT '0',
`option_type` enum('dropdown','switch','fingersizes') DEFAULT NULL,
`option_label` varchar(32) DEFAULT NULL,
`active` tinyint(1) DEFAULT '0',
`orderindex` int(2) DEFAULT '-1',
`created_at` int(11) DEFAULT NULL,
`updated_at` int(11) DEFAULT NULL,
`search` varchar(255) DEFAULT NULL,
`searchfilter` varchar(255) DEFAULT NULL,
`protected` tinyint(1) DEFAULT '0',
`option_requires` int(11) DEFAULT NULL,
`option_depends` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `is_option` (`is_option`)
) ENGINE=InnoDB AUTO_INCREMENT=47 DEFAULT CHARSET=utf8;
Any suggestions on how to improve the initial query time would be great
Thanks in advance :)
-- EDIT --
EXPLAIN SELECT query 1
EXPLAIN SELECT query 2

Answer 1

The first time you perform a query after starting the server, nothing is cache, so the query needs to fetch stuff from disk. All subsequent queries that access the same parts of the same tables will be much faster because of caching. This is "normal".
If you have the "Query cache" enable (it is probably enabled by default), then the second time you run exactly the same query, it will instantly find the result from the Query cache. By "exactly" I mean that not so much as a blank space has changed. Nearly all "production" servers are better off turning off the Query cache.
innodb_buffer_pool_size should be about 70% of available RAM. Changing the value won't affect a SELECT against a cold cache, but might help/hurt subsequent runs. This does not seem to be relevant in your case, since the second run was quite fast.
Please provide EXPLAIN SELECT ... so we can see how the optimizer decided to execute them.
LIKE '%c:35∆%' -- cannot use an index because of the leading wild card.
What is item_ids?
item_attribute is an EAV schema pattern. It sucks. Both the queries are ugly, and scalability hurts. It may help some to get rid of the id and make a compound PRIMARY KEY from a suitable combination of the other fields. The hope is to use the PRIMARY KEY which is clustered with the data instead of having to bounce from the secondary key. More discussion of EAV.
Assuming this has low cardinality, the index will probably never be used:
KEY is_option (is_option)