Optimizing MySQL
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This document discusses various methods for optimizing performance of MySQL databases, including upgrading hardware and software, optimizing configuration settings, optimizing queries, and optimizing database schemas. It provides an example of using EXPLAIN plans and adding indexes to optimize queries on a database table to improve performance. The author recommends focusing on query optimization as the best method, using profilers and slow query logs to identify queries to optimize.
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Optimizing MySQL
- 1. <Insert Picture Here> Optimizing MySQL Morgan Tocker, MySQL Community Manager http://www.tocker.ca/
- 2. Safe Harbor Statement The following is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.
- 3. Options • • • • Upgrade Hardware and/or MySQL Version Optimize Configuration Optimize Queries Optimize Schema
- 4. Commentary • There are some specific cases where upgrades can make individual queries faster (i.e. subqueries). When I like this optimization the most, is to increase“capacity”. Lots of multi-core, multi-disk enhancements in 5.5 / 5.6. • MySQL 5.6 comes with a much more optimized configuration. There are now only 3-4 settings that need to change. • Optimizing queries is my favourite method :) There can be some big wins here. • Optimizing schema relates to query optimization. Sometimes you have to change schema to support certain queries, but it always starts with the queries.
- 5. Optimizing Queries • Allows you to focus on queries that damage user experiences rather than just slow. • Best method is to install a profiler. • MySQL also supports slow query logging + Performance Schema (5.6+).
- 6. # Continent Asia + population > 5M! mysql> EXPLAIN SELECT * FROM Country WHERE continent='Asia' AND population > 5000000G! *************************** 1. row ***************************! id: 1! select_type: SIMPLE! table: Country! type: ALL! possible_keys: NULL! key: NULL! key_len: NULL! ref: NULL! rows: 267! Extra: Using where! 1 row in set (0.00 sec)
- 7. mysql> ALTER TABLE Country ADD INDEX p (population);! Query OK, 0 rows affected (0.02 sec)! Records: 0 Duplicates: 0 Warnings: 0! ! mysql> EXPLAIN SELECT * FROM Country WHERE continent='Asia' AND population > 5000000G! *************************** 1. row ***************************! id: 1! select_type: SIMPLE! table: Country! type: ALL! possible_keys: p! key: NULL! key_len: NULL! ref: NULL! rows: 264! Extra: Using where! 1 row in set (0.01 sec)
- 8. # 50 Million! mysql> EXPLAIN SELECT * FROM Country WHERE continent='Asia' AND population > 50000000G! *************************** 1. row ***************************! id: 1! select_type: SIMPLE! table: Country! type: range! possible_keys: p! key: p! key_len: 4! ref: NULL! rows: 24! Extra: Using index condition; Using where! 1 row in set (0.00 sec)
- 9. mysql> ALTER TABLE Country ADD INDEX c (continent);! Query OK, 0 rows affected (0.02 sec)! Records: 0 Duplicates: 0 Warnings: 0! ! mysql> EXPLAIN SELECT * FROM Country WHERE continent='Asia' ! AND population > 50000000G! *************************** 1. row ***************************! id: 1! select_type: SIMPLE! table: Country! type: ref! possible_keys: p,c! key: c! key_len: 1! ref: const! rows: 51! Extra: Using index condition; Using where! 1 row in set (0.00 sec)
- 10. mysql> ALTER TABLE Country ADD INDEX pc (population,continent);! Query OK, 0 rows affected (0.02 sec)! Records: 0 Duplicates: 0 Warnings: 0! ! mysql> EXPLAIN SELECT * FROM Country WHERE continent='Asia' ! AND population > 50000000G! *************************** 1. row ***************************! id: 1! select_type: SIMPLE! table: Country! type: ref! possible_keys: p,c,pc! key: c! key_len: 1! ref: const! rows: 51! Extra: Using index condition; Using where! 1 row in set (0.00 sec)
- 11. mysql> ALTER TABLE Country ADD INDEX cp (continent,population);! Query OK, 0 rows affected (0.01 sec)! Records: 0 Duplicates: 0 Warnings: 0! ! mysql> EXPLAIN SELECT * FROM Country WHERE continent='Asia' ! AND population > 50000000G! *************************** 1. row ***************************! id: 1! select_type: SIMPLE! table: Country! type: range! possible_keys: p,c,pc,cp! key: cp! key_len: 5! ref: NULL! rows: 11! Extra: Using index condition! 1 row in set (0.00 sec)
- 12. Tips • Think of where you can use indexes to eliminate rows - that’s the column you typically index. • Read: http://dev.mysql.com/doc/refman/5.6/en/ explain.html • Composite indexes somewhat an advanced topic: • Useful when a single column does not eliminate enough work. • “Ranges to the right”