Running a phpkb CMS on a ubuntu lamp server.
mysql – 5.5.28-0ubuntu0.12.04.3-log
The tables in this database are not large in fact I have not found one over 10k rows.
Every five min I get a 'copy to temp table' query that hangs out on the server and locks tables. It brings the site to a stand still. Mysql takes 100% of one of the four cores on the server sometimes over I assume taking resources from the other cores. It still hangs.
I have made a ram disk as suggested in other threads and still no performance gains. I'm starting to think it's just going to come down to query optimization for the one that hangs. This seems to be the query that kills it from show full processlist; I also have logged slow queries to the mysql logs and this is the one that shows up over and over.
# Query_time: 152.569759 Lock_time: 0.000075 Rows_sent: 1181 Rows_examined: 383893921
use newkbdb;
SET timestamp=1461243155;
SELECT
phpkb_articles.article_id AS article_id,
article_title,
article_content,
article_status,
article_date_time,
SUM(phpkb_article_visits.article_hits) AS article_hits
FROM
phpkb_articles
LEFT OUTER JOIN phpkb_article_visits ON (phpkb_article_visits.article_id
=phpkb_articles.article_id), phpkb_relations
WHERE
article_show='yes'
AND (phpkb_relations.article_id = phpkb_articles.article_id)
AND article_status IN ('featured','approved')
AND ( (article_expiry_date = '0000-00-00') OR (article_expiry_date <>
'0000-00-00' AND article_expiry_date >= now()) )
AND category_id=221 GROUP BY (phpkb_articles.article_id)
ORDER BY
FIELD(article_status,'featured','approved'),
article_title ASC;
Any suggestions or help appreciated I'm not a mysql dba this is just a unicorn site that some dept bought and now its become a huge dependency.
Thanks in advance.
UPDATE:
Create table statements:
CREATE TABLE `phpkb_articles` (
`article_id` int(11) NOT NULL AUTO_INCREMENT,
`author_id` int(11) NOT NULL,
`article_title` varchar(250) NOT NULL,
`article_content` longtext NOT NULL,
`article_date_time` datetime NOT NULL,
`article_status`enum('approved','disapproved','draft','featured','pending','pending-deleted','approved-deleted','featured-deleted','disapproved-deleted') NOT NULL DEFAULT 'pending',
`article_show` enum('yes','no') NOT NULL DEFAULT 'no',
`article_last_updation` datetime NOT NULL,
`article_keywords` varchar(250) NOT NULL,
`article_metadesc` varchar(250) NOT NULL,
`article_expiry_date` date NOT NULL,
`article_email_count` int(11) NOT NULL DEFAULT '0',
`article_print_count` int(11) NOT NULL DEFAULT '0',
`article_comments_allow` enum('yes','no') NOT NULL DEFAULT 'yes',
`article_ratings_allow` enum('yes','no') NOT NULL DEFAULT 'yes',
PRIMARY KEY (`article_id`),
FULLTEXT KEY `article_title` (`article_title`,`article_content`)
) ENGINE=MyISAM AUTO_INCREMENT=2872 DEFAULT CHARSET=utf8
CREATE TABLE `phpkb_relations` (
`relation_id` int(11) NOT NULL AUTO_INCREMENT,
`article_id` int(11) NOT NULL,
`category_id` int(11) NOT NULL,
PRIMARY KEY (`relation_id`)
) ENGINE=MyISAM AUTO_INCREMENT=21960 DEFAULT CHARSET=latin1
CREATE TABLE `phpkb_article_visits` (
`visit_id` int(11) NOT NULL AUTO_INCREMENT,
`article_id` int(11) NOT NULL,
`article_hits` int(11) NOT NULL,
`visit_date` date NOT NULL,
PRIMARY KEY (`visit_id`)
Best Answer
Indexes !
Use InnoDB, not MyISAM.
Reformulate the query so it does not 'explode' (
LEFT JOIN
), then 'implode' (GROUP BY
)...Something like:
article_*
fields belonging toarticle_hits
.)4.
Indexes needed:
article_expiry_date
.