16 MySQL Optimization #burningkeyboards
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The document discusses MySQL optimization. It provides details on using EXPLAIN to analyze query performance and the slow query log. It also summarizes using mysqltuner.pl to analyze a MySQL configuration and make recommendations such as disabling unused storage engines, defragmenting tables, enabling the slow query log, and adjusting certain variables like query_cache_size, tmp_table_size, and table_cache. Additional resources on MySQL optimization are also listed.
![MYSQL OPTIMIZATION
MYSQL OPTIMIZATION
โฃ mysqltunner.pl
โฃ https://raw.githubusercontent.com/major/MySQLTuner-perl/master/mysqltuner.pl
โฃ Before we start:
โฃ Change one setting at a time! This is the only way to estimate if a change is bene๏ฌcial.
โฃ Most settings can be changed at runtime with SET GLOBAL. It is very handy and it allows you to quickly
revert the change if it creates any problem. But in the end, you want the setting to be adjusted
permanently in the con๏ฌguration ๏ฌle.
โฃ A change in the con๏ฌguration is not visible even after a MySQL restart? Did you use the correct
con๏ฌguration ๏ฌle? Did you put the setting in the right section [mysqld]?
โฃ The server refuses to start after a change: did you use the correct unit? For instance,
innodb_buffer_pool_size should be set in bytes while max_connection is dimensionless.
โฃ Do not allow duplicate settings in the con๏ฌguration ๏ฌle. If you want to keep track of the changes, use
version control.
โฃ Donโt do naive math, like โmy new server has 2x RAM, Iโll just make all the values 2x the previous onesโ.
8](https://image.slidesharecdn.com/16-mysql-optimization-burningkeyboards-170712141453/85/16-MySQL-Optimization-burningkeyboards-8-320.jpg)
![MYSQL OPTIMIZATION
MYSQL OPTIMIZATION
./mysqltuner.pl
>> MySQLTuner 0.9.8 - Major Hayden <major@mhtx.net>
>> Bug reports, feature requests, and downloads at http://mysqltuner.com/
>> Run with '--help' for additional options and output filtering
Please enter your MySQL administrative login: <-- root
Please enter your MySQL administrative password: <-- yourrootsqlpassword
-------- General Statistics --------------------------------------------------
[--] Skipped version check for MySQLTuner script
[!!] Your MySQL version 4.1.11-Debian_etch1-log is EOL software! Upgrade soon!
[OK] Operating on 32-bit architecture with less than 2GB RAM
-------- Storage Engine Statistics -------------------------------------------
[--] Status: +Archive -BDB -Federated +InnoDB +ISAM -NDBCluster
[--] Data in MyISAM tables: 301M (Tables: 2074)
[--] Data in HEAP tables: 379K (Tables: 9)
[!!] InnoDB is enabled but isn't being used
[!!] ISAM is enabled but isn't being used
[!!] Total fragmented tables: 215
-------- Performance Metrics -------------------------------------------------
[--] Up for: 12d 18h 33m 30s (1B q [1K qps], 185K conn, TX: 3B, RX: 377M)
[--] Reads / Writes: 78% / 22%
[--] Total buffers: 2.6M per thread and 58.0M global
[OK] Maximum possible memory usage: 320.5M (20% of installed RAM)
[OK] Slow queries: 0% (17/1B)
[OK] Highest usage of available connections: 32% (32/100)
[OK] Key buffer size / total MyISAM indexes: 16.0M/72.3M
[OK] Key buffer hit rate: 99.9%
[OK] Query cache efficiency: 99.9%
[!!] Query cache prunes per day: 47549
[OK] Sorts requiring temporary tables: 0%
[!!] Temporary tables created on disk: 28%
[OK] Thread cache hit rate: 99%
[!!] Table cache hit rate: 0%
[OK] Open file limit used: 12%
[OK] Table locks acquired immediately: 99%
[!!] Connections aborted: 20%
9](https://image.slidesharecdn.com/16-mysql-optimization-burningkeyboards-170712141453/85/16-MySQL-Optimization-burningkeyboards-9-320.jpg)
![Introduction into MySQL Query Tuning for Dev[Op]s](https://cdn.slidesharecdn.com/ss_thumbnails/qtdevops-210717011329-thumbnail.jpg?width=560&fit=bounds)
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16 MySQL Optimization #burningkeyboards
- 3. MYSQL OPTIMIZATION EXPLAIN desc recipes; +-------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------------+--------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | varchar(400) | NO | MUL | NULL | | | description | text | YES | | NULL | | | category_id | int(11) | YES | MUL | NULL | | | chef_id | int(255) | NO | MUL | NULL | | | created | datetime | YES | | NULL | | +-------------+--------------+------+-----+---------+----------------+ 3
- 4. MYSQL OPTIMIZATION EXPLAIN EXPLAIN select name, created from recipes where created > '2011-11-01 00:00:00'; *************************** 1. row *************************** id: 1 select_type: SIMPLE table: recipes type: ALL possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: 5 Extra: Using where 4
- 5. MYSQL OPTIMIZATION EXPLAIN insert into j1 values (1); insert into j2 select * from j1; insert into j3 select * from j2; explain extended select j1.c1 from j1, j2, j3 where j1.c1 = j2.c1 and j3.c1 = j1.c1; +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | 1 | SIMPLE | j1 | ALL | NULL | NULL | NULL | NULL | 2 | | | 1 | SIMPLE | j2 | ALL | NULL | NULL | NULL | NULL | 3 | Using where | | 1 | SIMPLE | j3 | ALL | NULL | NULL | NULL | NULL | 4 | Using where | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ 3 rows in set, 1 warning (0.00 sec) show warnings; +-------+------+------------------------------------------------------------------------------------------------------+ | Level | Code | Message +-------+------+------------------------------------------------------------------------------------------------------+ | Note | 1003 | select `test`.`j1`.`c1` AS `c1` from `test`.`j1` join `test`.`j2` join `test`.`j3` where ((`test`.`j2`.`c1` = `test`.`j1`.`c1`) and (`test`.`j3`.`c1` = `test`.`j1`.`c1`)) | +-------+------+------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec) 5
- 6. MYSQL OPTIMIZATION SLOW QUERY LOG โฃ The slow query log is disabled by default. โฃ To enable it, set the slow_query_log system variable to 1. โฃ The log_output server system variable determines how the output will be written, and can also disable it. โฃ By default, the log is written to ๏ฌle, but it can also be written to table. โฃ The name of the ๏ฌle is determined by the -- slow_query_log_file=file_name option, by default host_name- slow.log, while the table used is the slow_log table in the mysql database. 6
- 7. MYSQL OPTIMIZATION SLOW QUERY LOG โฃ Slow query is de๏ฌned as a query that takes longer than long_query_time to run, by default 10 seconds. Microseconds are allowed for logging into ๏ฌle, but not for logging into a table. This value can be adjusted dynamically. โฃ By default only non-administrative statements are logged, as well as queries that use indexes. It can be particularly useful to include queries without indexes in the log (regardless of time taken), and this is set with the log_queries_not_using_indexes setting. Queries on tables containing 0 rows or 1 row will not be logged. โฃ Slow administrative queries, which include ALTER TABLE, ANALYZE TABLE, CHECK TABLE, CREATE INDEX, DROP INDEX, OPTIMIZE TABLE, and REPAIR TABLE statements, can also be stored by using the --log-slow- admin-statements setting. 7
- 8. MYSQL OPTIMIZATION MYSQL OPTIMIZATION โฃ mysqltunner.pl โฃ https://raw.githubusercontent.com/major/MySQLTuner-perl/master/mysqltuner.pl โฃ Before we start: โฃ Change one setting at a time! This is the only way to estimate if a change is bene๏ฌcial. โฃ Most settings can be changed at runtime with SET GLOBAL. It is very handy and it allows you to quickly revert the change if it creates any problem. But in the end, you want the setting to be adjusted permanently in the con๏ฌguration ๏ฌle. โฃ A change in the con๏ฌguration is not visible even after a MySQL restart? Did you use the correct con๏ฌguration ๏ฌle? Did you put the setting in the right section [mysqld]? โฃ The server refuses to start after a change: did you use the correct unit? For instance, innodb_buffer_pool_size should be set in bytes while max_connection is dimensionless. โฃ Do not allow duplicate settings in the con๏ฌguration ๏ฌle. If you want to keep track of the changes, use version control. โฃ Donโt do naive math, like โmy new server has 2x RAM, Iโll just make all the values 2x the previous onesโ. 8
- 9. MYSQL OPTIMIZATION MYSQL OPTIMIZATION ./mysqltuner.pl >> MySQLTuner 0.9.8 - Major Hayden <[email protected]> >> Bug reports, feature requests, and downloads at http://mysqltuner.com/ >> Run with '--help' for additional options and output filtering Please enter your MySQL administrative login: <-- root Please enter your MySQL administrative password: <-- yourrootsqlpassword -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [!!] Your MySQL version 4.1.11-Debian_etch1-log is EOL software! Upgrade soon! [OK] Operating on 32-bit architecture with less than 2GB RAM -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB -Federated +InnoDB +ISAM -NDBCluster [--] Data in MyISAM tables: 301M (Tables: 2074) [--] Data in HEAP tables: 379K (Tables: 9) [!!] InnoDB is enabled but isn't being used [!!] ISAM is enabled but isn't being used [!!] Total fragmented tables: 215 -------- Performance Metrics ------------------------------------------------- [--] Up for: 12d 18h 33m 30s (1B q [1K qps], 185K conn, TX: 3B, RX: 377M) [--] Reads / Writes: 78% / 22% [--] Total buffers: 2.6M per thread and 58.0M global [OK] Maximum possible memory usage: 320.5M (20% of installed RAM) [OK] Slow queries: 0% (17/1B) [OK] Highest usage of available connections: 32% (32/100) [OK] Key buffer size / total MyISAM indexes: 16.0M/72.3M [OK] Key buffer hit rate: 99.9% [OK] Query cache efficiency: 99.9% [!!] Query cache prunes per day: 47549 [OK] Sorts requiring temporary tables: 0% [!!] Temporary tables created on disk: 28% [OK] Thread cache hit rate: 99% [!!] Table cache hit rate: 0% [OK] Open file limit used: 12% [OK] Table locks acquired immediately: 99% [!!] Connections aborted: 20% 9
- 10. MYSQL OPTIMIZATION MYSQL OPTIMIZATION -------- Recommendations ----------------------------------------------------- General recommendations: Add skip-innodb to MySQL configuration to disable InnoDB Add skip-isam to MySQL configuration to disable ISAM Run OPTIMIZE TABLE to defragment tables for better performance Enable the slow query log to troubleshoot bad queries When making adjustments, make tmp_table_size/max_heap_table_size equal Reduce your SELECT DISTINCT queries without LIMIT clauses Increase table_cache gradually to avoid file descriptor limits Your applications are not closing MySQL connections properly Variables to adjust: query_cache_size (> 16M) tmp_table_size (> 32M) max_heap_table_size (> 16M) table_cache (> 64) 10
- 11. MYSQL OPTIMIZATION MYSQL OPTIMIZATION RESOURCES โฃ MySQL Documentation โฃ https://dev.mysql.com/doc/refman/5.7/en/optimization.html โฃ How to Optimize MySQL Performance Using MySQLTuner โฃ https://www.linode.com/docs/databases/mysql/how-to-optimize- mysql-performance-using-mysqltuner 11