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 :/)
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 | |
+-------+------------+--------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+
Answer
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_sizeinnodb_log_buffer_sizeinnodb_flush_log_at_trx_commitinnodb_thread_concurrencyinnodb_flush_method=O_DIRECTinnodb_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
EXPLAINto make sure the index is really being used
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