How to fine-tune our MySQL server?
Solution 1
You probably shouldn't consider MyISAM, INNODB will work for you. MyISAM is maybe faster when it comes to SELECT
but (for example) it locks your full table on updates.
As for INNODB:
- generally, always consider more RAM before you go into sharding (size of the DB =~ RAM)
- take a look at the following variables:
-
innodb_buffer_pool_size
(we use roughly 60-70% of our memory) innodb_log_file_size
innodb_log_buffer_size
innodb_flush_log_at_trx_commit
innodb_thread_concurrency
innodb_flush_method=O_DIRECT
innodb_file_per_table
-
- switch from innodb to xtradb (same API)
- use the percona builds (they contain performance patches from Google, etc.)
Great reads:
On a side note:
- a 2 GB slice is just not enough to run this
- further more I found the storage on slicehost to be rather slow (io is a factor)
- in the cloud it may make sense to shard earlier (cause of the RAM limit)
- I'd run all queries through
EXPLAIN
to make sure the index is really being used
Solution 2
I've found MySQLTuner to be very effective in the past -- it can make sensible suggestions for configuration changes based on the usage of your server. It's based on the tuning-primer script, which is also worth a try.
Solution 3
Does your app release the connections to the pool when it finishes its stuff ?
Julien Genestoux
Cofounder of Superfeedr, acquired by Medium.
Updated on September 17, 2022Comments
-
Julien Genestoux over 1 year
MySQL is not my thing, yet I need to fine-tune one of our servers.
Here are the requirements/specs:
- The MySQL server has only one significant database
- We only have one "type" of application connected to it, and not many instances at the same time are connected to it : at most 15. (these applications are XMPP bots)
- These application have a non-blocking
IO, which means that they never
"wait" on the DB server and continue
dealing with incoming requests while
the DB queries are being processed.
It implies that sometime one instance
of this application can have several
(a lot!) connections to the database
server (specially if some queries are
slow)
- All the queries are using indices
- Our host machine only runs MySQL. It's a Xen instance (@slicehost) with 2GB of RAM.
- We use InnoDB table because we need some basic transactions, but we could probably switch to MyISAM if this had a real impact on performance.
As it is configured right now, our MySQL server slowly starts to eat the all the available memory (we use collectd, here is a graph). At some point (after a few days/weeks), it stops performing queries (it stopped this night for 2 hours, and I had to restart the MySQL server : see 2nd image) :
(sorry, new usrs can't post images, and only 1 hyperlink :/)
Weekly : http://i27.tinypic.com/6ticyv.jpg
Today : i31.tinypic.com/ir53yg.png
Here is our current my.cnf
# # The MySQL database server configuration file. # # This will be passed to all mysql clients # It has been reported that passwords should be enclosed with ticks/quotes # escpecially if they contain "#" chars... # Remember to edit /etc/mysql/debian.cnf when changing the socket location. [client] port = 3306 socket = /var/run/mysqld/mysqld.sock # Here is entries for some specific programs # The following values assume you have at least 32M ram # This was formally known as [safe_mysqld]. Both versions are currently parsed. [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] # # * Basic Settings # # # * IMPORTANT # If you make changes to these settings and your system uses apparmor, you may # also need to also adjust /etc/apparmor.d/usr.sbin.mysqld. # user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp language = /usr/share/mysql/english skip-external-locking # # Instead of skip-networking the default is now to listen only on # localhost which is more compatible and is not less secure. # yann changed this on a friday balbla #bind-address = 127.0.0.1 bind-address = 0.0.0.0 # # * Fine Tuning # key_buffer = 16M max_allowed_packet = 16M thread_stack = 128K thread_cache_size = 8 # This replaces the startup script and checks MyISAM tables if needed # the first time they are touched myisam-recover = BACKUP max_connections = 2000 #table_cache = 64 #thread_concurrency = 10 # # * Query Cache Configuration # query_cache_limit = 1M query_cache_size = 16M # # * Logging and Replication # # Both location gets rotated by the cronjob. # Be aware that this log type is a performance killer. # log = /var/log/mysql/mysql.log # # Error logging goes to syslog. This is a Debian improvement :) # # Here you can see queries with especially long duration log_slow_queries = /var/log/mysql/mysql-slow.log long_query_time = 3 log-queries-not-using-indexes # # The following can be used as easy to replay backup logs or for replication. # note: if you are setting up a replication slave, see README.Debian about # other settings you may need to change. #server-id = 1 #log_bin = /var/log/mysql/mysql-bin.log expire_logs_days = 10 max_binlog_size = 100M #binlog_do_db = include_database_name #binlog_ignore_db = include_database_name # # * BerkeleyDB # # Using BerkeleyDB is now discouraged as its support will cease in 5.1.12. skip-bdb # # * InnoDB # # InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/. # Read the manual for more InnoDB related options. There are many! # You might want to disable InnoDB to shrink the mysqld process by circa 100MB. #skip-innodb # Fine tunig added by JG on 06/03 based on http://www.mysqlperformanceblog.com/2007/11/01/innodb-performance-optimization-basics/ innodb_buffer_pool_size = 1G #innodb_log_file_size = 256M innodb_log_buffer_size = 4M innodb_flush_log_at_trx_commit = 2 innodb_thread_concurrency = 8 innodb_flush_method = O_DIRECT innodb_file_per_table transaction-isolation = READ-COMMITTED innodb_table_locks = 0 # # * Federated # # The FEDERATED storage engine is disabled since 5.0.67 by default in the .cnf files # shipped with MySQL distributions (my-huge.cnf, my-medium.cnf, and so forth). # skip-federated # # * Security Features # # Read the manual, too, if you want chroot! # chroot = /var/lib/mysql/ # # For generating SSL certificates I recommend the OpenSSL GUI "tinyca". # # ssl-ca=/etc/mysql/cacert.pem # ssl-cert=/etc/mysql/server-cert.pem # ssl-key=/etc/mysql/server-key.pem [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] #no-auto-rehash # faster start of mysql but no tab completition [isamchk] key_buffer = 16M # # * NDB Cluster # # See /usr/share/doc/mysql-server-*/README.Debian for more information. # # The following configuration is read by the NDB Data Nodes (ndbd processes) # not from the NDB Management Nodes (ndb_mgmd processes). # # [MYSQL_CLUSTER] # ndb-connectstring=127.0.0.1 # # * IMPORTANT: Additional settings that can override those from this file! # The files must end with '.cnf', otherwise they'll be ignored. # !includedir /etc/mysql/conf.d/
Here is a dump of slow queries:
$ mysqldumpslow /var/log/mysql/mysql-slow.log Reading mysql slow query log from /var/log/mysql/mysql-slow.log Count: 5 Time=3689348814741910528.00s (-1s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] SET insert_id=N; INSERT IGNORE INTO `feeds` (`url`) VALUES ('S') Count: 41 Time=1349761761490942720.00s (-1s) Lock=0.12s (5s) Rows=253.0 (10373), superfeeder[superfeeder]@localhost SHOW GLOBAL STATUS Count: 25 Time=737869762948382080.00s (-1s) Lock=0.00s (0s) Rows=18.1 (452), superfeeder[superfeeder]@[172.21.1.158] SELECT `feeds`.* FROM `feeds` WHERE (`fetch_session_id` = 'S') Count: 12952 Time=1424239042133230.25s (-1s) Lock=0.00s (1s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] SET insert_id=N; INSERT IGNORE INTO `entries` (`chunks`, `time`, `feed_id`, `unique_id`, `link`, `chunk`) VALUES ('S', 'S', N, 'S', 'S', 'S') Count: 29 Time=656.55s (19040s) Lock=5.28s (153s) Rows=0.8 (23), superfeeder[superfeeder]@[172.21.1.175] select salt,crypted_password from users where login='S' Count: 39 Time=505.23s (19704s) Lock=2.41s (94s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] DELETE FROM `feeds` WHERE (url LIKE 'S') Count: 2275 Time=502.50s (1143184s) Lock=3.48s (7922s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] UPDATE `feeds` SET `next_fetch` = 'S', `fetch_session_id` = 'S' WHERE (`next_fetch` < 'S') LIMIT N Count: 1 Time=443.00s (443s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] UPDATE `feeds` SET `next_fetch` = 'S' WHERE (`feeds`.`url` IN (NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL)) Count: 14 Time=289.43s (4052s) Lock=0.71s (10s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] UPDATE `feeds` SET `next_fetch` = 'S' WHERE (`feeds`.`url` IN ('S','S')) Count: 2 Time=256.00s (512s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] UPDATE `feeds` SET `next_fetch` = 'S' WHERE (`feeds`.`url` IN (NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL)) Count: 1 Time=237.00s (237s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] UPDATE `feeds` SET `next_fetch` = 'S' WHERE (`feeds`.`url` IN ('S')) Count: 24 Time=191.58s (4598s) Lock=1.12s (27s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] UPDATE `feeds` SET `next_fetch` = 'S' WHERE (`feeds`.`id` = 'S') Count: 5 Time=144.20s (721s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] UPDATE `feeds` SET `next_fetch` = 'S' WHERE (`feeds`.`url` IN (NULL,NULL,NULL)) Count: 1 Time=101.00s (101s) Lock=1.00s (1s) Rows=1.0 (1), superfeeder[superfeeder]@[172.21.1.158] SELECT * FROM `users` WHERE (`login` = 'S') LIMIT N Count: 79 Time=35.51s (2805s) Lock=2.52s (199s) Rows=0.2 (12), superfeeder[superfeeder]@[172.21.1.184] SELECT `feeds`.id FROM `feeds` WHERE (`feeds`.`url` = BINARY 'S' AND `feeds`.id <> N) LIMIT N Count: 1 Time=28.00s (28s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] UPDATE `feeds` SET `last_maintenance_at` = 'S', `updated_at` = 'S' WHERE `id` = N Count: 51 Time=23.51s (1199s) Lock=0.12s (6s) Rows=19.2 (981), superfeeder[superfeeder]@2hosts SELECT version FROM schema_migrations Count: 5 Time=20.60s (103s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] BEGIN Count: 65 Time=15.86s (1031s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] UPDATE `feeds` SET `last_error_message` = 'S', `period` = 'S', `last_sup_update_id` = NULL, `updated_at` = 'S', `modified` = 'S', `fetch_session_id` = 'S', `streamed` = 'S', `last_parse` = 'S', `etag` = 'S', `last_entry_time` = 'S', `min_period` = 'S', `url` = 'S', `id` = 'S', `feed_type` = NULL, `sup_id` = NULL, `sup_url_id` = NULL, `next_fetch` = 'S', `hashed_content` = 'S', `last_maintenance_at` = 'S', `last_ping` = NULL, `last_http_code` = 'S', `active` = 'S', `last_fetch` = 'S', `created_at` = 'S', `max_period` = 'S' WHERE (`id` = N) Count: 23 Time=11.52s (265s) Lock=0.00s (0s) Rows=231.0 (5313), superfeeder[superfeeder]@2hosts # Count: 132 Time=10.53s (1390s) Lock=0.02s (2s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] UPDATE `feeds` SET `last_error_message` = 'S', `period` = 'S', `last_sup_update_id` = NULL, `updated_at` = 'S', `modified` = 'S', `fetch_session_id` = 'S', `streamed` = 'S', `last_parse` = 'S', `etag` = 'S', `last_entry_time` = 'S', `min_period` = 'S', `url` = 'S', `id` = 'S', `feed_type` = NULL, `sup_id` = NULL, `sup_url_id` = NULL, `next_fetch` = 'S', `hashed_content` = 'S', `last_maintenance_at` = 'S', `last_ping` = NULL, `last_http_code` = 'S', `active` = 'S', `last_fetch` = 'S', `created_at` = NULL, `max_period` = 'S' WHERE (`id` = N) Count: 62 Time=9.81s (608s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.184] ROLLBACK Count: 151 Time=8.94s (1350s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@2hosts DELETE FROM `entries` WHERE (`time` < 'S') Count: 25 Time=8.76s (219s) Lock=0.00s (0s) Rows=1.0 (24), superfeeder[superfeeder]@[172.21.1.158] SELECT * FROM `feeds` WHERE (`url` = 'S') LIMIT N Count: 2 Time=8.50s (17s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] set SQL_AUTO_IS_NULL=N Count: 8802 Time=8.44s (74319s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] INSERT IGNORE INTO `entries` (`chunks`, `time`, `feed_id`, `unique_id`, `link`, `chunk`) VALUES ('S', 'S', N, 'S', 'S', 'S') Count: 1 Time=8.00s (8s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] INSERT IGNORE INTO `subscriptions` (`user_id`, `feed_id`) VALUES (N, N) Count: 38 Time=7.92s (301s) Lock=0.00s (0s) Rows=1.0 (38), superfeeder[superfeeder]@[172.21.1.184] SELECT count(DISTINCT `users`.id) AS count_users_id FROM `users` INNER JOIN `subscriptions` ON `users`.id = `subscriptions`.user_id WHERE ((`subscriptions`.feed_id = N)) Count: 9 Time=7.67s (69s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] INSERT IGNORE INTO `feeds` (`url`) VALUES ('S') Count: 244 Time=7.20s (1756s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] UPDATE `feeds` SET `last_error_message` = 'S', `period` = N, `last_sup_update_id` = NULL, `updated_at` = 'S', `modified` = 'S', `fetch_session_id` = 'S', `streamed` = 'S', `last_parse` = 'S', `etag` = 'S', `last_entry_time` = 'S', `min_period` = 'S', `url` = 'S', `id` = 'S', `feed_type` = NULL, `sup_id` = NULL, `sup_url_id` = NULL, `next_fetch` = 'S', `hashed_content` = 'S', `last_maintenance_at` = 'S', `last_ping` = NULL, `last_http_code` = N, `active` = 'S', `last_fetch` = 'S', `created_at` = 'S', `max_period` = 'S' WHERE (`id` = N) Count: 336 Time=6.85s (2301s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] UPDATE `feeds` SET `last_error_message` = 'S', `period` = N, `last_sup_update_id` = NULL, `updated_at` = 'S', `modified` = 'S', `fetch_session_id` = 'S', `streamed` = 'S', `last_parse` = 'S', `etag` = 'S', `last_entry_time` = 'S', `min_period` = 'S', `url` = 'S', `id` = 'S', `feed_type` = NULL, `sup_id` = NULL, `sup_url_id` = NULL, `next_fetch` = 'S', `hashed_content` = 'S', `last_maintenance_at` = 'S', `last_ping` = NULL, `last_http_code` = N, `active` = 'S', `last_fetch` = 'S', `created_at` = NULL, `max_period` = 'S' WHERE (`id` = N) Count: 16 Time=6.38s (102s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] UPDATE `feeds` SET `last_error_message` = 'S', `period` = N, `last_sup_update_id` = NULL, `updated_at` = NULL, `modified` = 'S', `fetch_session_id` = 'S', `streamed` = 'S', `last_parse` = 'S', `etag` = 'S', `last_entry_time` = 'S', `min_period` = 'S', `url` = 'S', `id` = 'S', `feed_type` = NULL, `sup_id` = NULL, `sup_url_id` = NULL, `next_fetch` = 'S', `hashed_content` = 'S', `last_maintenance_at` = 'S', `last_ping` = NULL, `last_http_code` = N, `active` = 'S', `last_fetch` = 'S', `created_at` = NULL, `max_period` = 'S' WHERE (`id` = N) Count: 122 Time=5.91s (721s) Lock=0.00s (0s) Rows=1.0 (119), superfeeder[superfeeder]@[172.21.1.158] SELECT DISTINCT `users`.* FROM `users` INNER JOIN `subscriptions` ON (`subscriptions`.`user_id` = `users`.`id`) WHERE (`subscriptions`.`feed_id` = N) Count: 299 Time=5.78s (1727s) Lock=0.00s (0s) Rows=1.0 (299), superfeeder[superfeeder]@[172.21.1.158] SELECT * FROM `feeds` WHERE (`id` = 'S') Count: 21 Time=5.48s (115s) Lock=0.00s (0s) Rows=1.0 (21), superfeeder[superfeeder]@[172.21.1.158] SELECT * FROM `subscriptions` WHERE ((`user_id` = N) AND (`feed_id` = N)) LIMIT N Count: 27 Time=5.37s (145s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] UPDATE `feeds` SET `last_error_message` = 'S', `period` = 'S', `last_sup_update_id` = NULL, `updated_at` = NULL, `modified` = 'S', `fetch_session_id` = 'S', `streamed` = 'S', `last_parse` = 'S', `etag` = 'S', `last_entry_time` = 'S', `min_period` = 'S', `url` = 'S', `id` = 'S', `feed_type` = NULL, `sup_id` = NULL, `sup_url_id` = NULL, `next_fetch` = 'S', `hashed_content` = 'S', `last_maintenance_at` = 'S', `last_ping` = NULL, `last_http_code` = 'S', `active` = 'S', `last_fetch` = 'S', `created_at` = NULL, `max_period` = 'S' WHERE (`id` = N) Count: 9 Time=4.33s (39s) Lock=0.00s (0s) Rows=0.0 (0), superfeeder[superfeeder]@[172.21.1.158] UPDATE `feeds` SET `last_error_message` = 'S', `period` = 'S', `last_sup_update_id` = NULL, `updated_at` = NULL, `modified` = 'S', `fetch_session_id` = 'S', `streamed` = 'S', `last_parse` = 'S', `etag` = 'S', `last_entry_time` = 'S', `min_period` = 'S', `url` = 'S', `id` = 'S', `feed_type` = NULL, `sup_id` = NULL, `sup_url_id` = NULL, `next_fetch` = 'S', `hashed_content` = 'S', `last_maintenance_at` = 'S', `last_ping` = NULL, `last_http_code` = NULL, `active` = 'S', `last_fetch` = 'S', `created_at` = NULL, `max_period` = 'S' WHERE (`id` = N) Count: 1 Time=4.00s (4s) Lock=0.00s (0s) Rows=1.0 (1), superfeeder[superfeeder]@[172.21.1.175] select id from users where login='S' Count: 1 Time=3.00s (3s) Lock=0.00s (0s) Rows=22.0 (22), debian-sys-maint[debian-sys-maint]@localhost select concat("S", TABLE_SCHEMA, "S", TABLE_NAME, "S") from information_schema.TABLES where ENGINE="S" Count: 1056 Time=0.11s (111s) Lock=0.00s (0s) Rows=126.9 (133998), superfeeder[superfeeder]@[172.21.1.184] SELECT * FROM `feeds` WHERE (last_maintenance_at < 'S') Count: 1049 Time=0.00s (1s) Lock=0.00s (0s) Rows=3.1 (3303), superfeeder[superfeeder]@[172.21.1.184] SELECT * FROM `users` WHERE (one_week_anniversary_sent = N AND activated_at < 'S') Count: 21 Time=0.00s (0s) Lock=0.00s (0s) Rows=0.0 (0), 0users@0hosts administrator command: Ping Count: 1 Time=0.00s (0s) Lock=0.00s (0s) Rows=0.0 (0), debian-sys-maint[debian-sys-maint]@localhost select count(*) into @discard from `information_schema`.`COLUMNS` Count: 8 Time=0.00s (0s) Lock=0.00s (0s) Rows=30.0 (240), superfeeder[superfeeder]@[172.21.1.184] SELECT DISTINCT `feeds`.* FROM `feeds` INNER JOIN `subscriptions` ON `feeds`.id = `subscriptions`.feed_id WHERE ((`subscriptions`.user_id = N)) AND ((`subscriptions`.user_id = N)) LIMIT N, N Count: 31 Time=0.00s (0s) Lock=0.00s (0s) Rows=1.0 (31), superfeeder[superfeeder]@2hosts SELECT count(*) AS count_all FROM `feeds` Count: 1 Time=0.00s (0s) Lock=0.00s (0s) Rows=0.0 (0), debian-sys-maint[debian-sys-maint]@localhost select count(*) into @discard from `information_schema`.`TRIGGERS` Count: 1 Time=0.00s (0s) Lock=0.00s (0s) Rows=0.0 (0), debian-sys-maint[debian-sys-maint]@localhost select count(*) into @discard from `information_schema`.`VIEWS` Count: 52 Time=0.00s (0s) Lock=0.00s (0s) Rows=0.7 (34), superfeeder[superfeeder]@[172.21.1.184] SELECT * FROM `users` WHERE (`users`.`remember_token` = 'S') LIMIT N Count: 120 Time=0.00s (0s) Lock=0.00s (0s) Rows=1.0 (120), superfeeder[superfeeder]@2hosts SELECT * FROM `feeds` ORDER BY feeds.id DESC LIMIT N Count: 19 Time=0.00s (0s) Lock=0.00s (0s) Rows=15.7 (299), superfeeder[superfeeder]@2hosts SELECT count(*) AS count_all, last_http_code AS last_http_code FROM `feeds` GROUP BY last_http_code Count: 1 Time=0.00s (0s) Lock=0.00s (0s) Rows=0.0 (0), debian-sys-maint[debian-sys-maint]@localhost select count(*) into @discard from `information_schema`.`ROUTINES` Count: 1 Time=0.00s (0s) Lock=0.00s (0s) Rows=1.0 (1), debian-sys-maint[debian-sys-maint]@localhost SELECT count(*) FROM mysql.user WHERE user='S' and password='S'
Table definition for feeds :
+---------------------+--------------+------+-----+---------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------------+--------------+------+-----+---------------------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | url | varchar(255) | YES | UNI | NULL | | | last_parse | datetime | YES | | 2009-08-10 14:51:46 | | | etag | varchar(255) | YES | | etag | | | modified | datetime | YES | | 2009-08-10 14:51:46 | | | active | tinyint(1) | YES | MUL | 1 | | | last_fetch | datetime | YES | | 2009-08-10 14:51:46 | | | next_fetch | datetime | YES | MUL | 2009-08-10 14:51:46 | | | fetch_session_id | varchar(255) | YES | MUL | | | | period | int(11) | YES | | 240 | | | hashed_content | varchar(255) | YES | | | | | streamed | tinyint(1) | YES | | 0 | | | sup_id | varchar(255) | YES | MUL | NULL | | | last_sup_update_id | varchar(255) | YES | | NULL | | | last_entry_time | datetime | YES | | 2009-08-10 14:51:46 | | | last_ping | datetime | YES | | NULL | | | last_http_code | int(11) | YES | | NULL | | | last_error_message | varchar(255) | YES | | | | | sup_url_id | int(11) | YES | MUL | NULL | | | created_at | datetime | YES | | NULL | | | updated_at | datetime | YES | | NULL | | | last_maintenance_at | datetime | YES | | 2008-08-10 21:51:50 | | | min_period | int(11) | YES | | 60 | | | max_period | int(11) | YES | | 900 | | +---------------------+--------------+------+-----+---------------------+----------------+ +-------+------------+--------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | +-------+------------+--------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+ | feeds | 0 | PRIMARY | 1 | id | A | 166 | NULL | NULL | | BTREE | | | feeds | 0 | index_feeds_on_url | 1 | url | A | 166 | NULL | NULL | YES | BTREE | | | feeds | 1 | index_feeds_on_next_fetch_and_active | 1 | next_fetch | A | 1 | NULL | NULL | YES | BTREE | | | feeds | 1 | index_feeds_on_next_fetch_and_active | 2 | active | A | 1 | NULL | NULL | YES | BTREE | | | feeds | 1 | index_feeds_on_sup_id | 1 | sup_id | A | 1 | NULL | NULL | YES | BTREE | | | feeds | 1 | index_feeds_on_sup_url_id | 1 | sup_url_id | A | 1 | NULL | NULL | YES | BTREE | | | feeds | 1 | index_feeds_on_fetch_session_id | 1 | fetch_session_id | A | 1 | NULL | NULL | YES | BTREE | | +-------+------------+--------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+
-
Julien Genestoux over 14 yearsSorry, but I don't see the point? We're not doing any search on our database...
-
Julien Genestoux over 14 yearsYeah, the happen when the server blocks, and again, I've checked all queries : they all use indices. ( + the slowest queries are also INSERT queries... which doesn't have anything to do with indices, AFAIK)
-
Julien Genestoux over 14 yearsGreat response! Right now, our database size is 61M... so if I believe your statement DB =~ RAM; we have wayyy enough RAM! I think storage is indeed slow (because it is virtualized I guess). I'll read your links. Thanks!
-
Julien Genestoux over 14 years(and yeah, I have ran all queries through EXPLAIN and they all use indices)
-
Till over 14 yearsHey Julien -- first off, you vote up answers around here. ;-) Secondly, just having RAM is of no use if MySQL isn't using it. Make sure you double-check the settings so it uses them.
-
Julien Genestoux over 14 yearsYeah, well that is exactly where I need my help ;) I think MySQL uses it. (and actually too much!, because our server seems to run out of RAM after some point). The DB is size if 61M, how come it "eats" 2GB of RAM?
-
Till over 14 yearsCan you add the table definition for your "worst" query?
-
Till over 14 years(e.g. the feeds table)
-
Mark L over 14 yearsYou are: .. WHERE (
feeds
.url
IN (NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL)) .. .. WHERE (feeds
.url
IN ('S','S')) .. Those could be more expensive than finding the integer id's via sphinx first and using sphinx you can push the load off to another server easily with worrying about master-slave setups and bin log delays. -
Julien Genestoux over 14 yearsfeeds.url is a index. Is the primary key faster than an index?
-
Mark L over 14 yearsIf it were an integer instead of (I'm assuming) a VARCHAR(10) or something like that then yeah, the integer would use less space and mysql could find it in the index table quicker.
-
Julien Genestoux over 14 yearsNope, because it's never done with them actually. It's not like a webapp where the app "dies" between connections.
-
Julien Genestoux over 14 yearsYeah, I added it in the post.
-
Julien Genestoux over 14 yearsBut wouldn't that be really marginal?