php性能优化

1.PHP语言级的性能优化

 1.1多用php自身能力

 1.2php内置函数优化

 1.3少用魔法函数

 1.4合理使用内存

 1.5避免在循环内做运算

1.6减少大规模计算

  

 2.mysql优化

 

1)查看mysql是否开启慢查询日志
show variables like 'slow_query_log';
2)设置没有索引的记录到慢查询日志
set global log_queries_not_using_indexes=on;

3)查看超过多长时间的sql进行记录到慢查询日志
show variables like 'long_query_time'
4)开启慢查询日志
set global slow_query_log=on

1.MYSQL分析工具--mysqldumpslow

 2.如何通过日志发现有问题的SQL

 3.explain返回含义

 4.group by优化

group by可能会出现临时表（Using temporary），文件排序（Using filesort）等，影响效率。
可以通过关联的子查询，来避免产生临时表和文件排序，可以节省io
改写前
select actor.first_name,actor.last_name,count(*)
from sakila.film_actor

 5.如何建立合适的列索引

 

如何判断列的离散程度

 

 

 

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 1

Server version: 5.6.17 MySQL Community Server (GPL)

 

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

 

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

 

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

 

mysql> show databases;

+--------------------+

| Database           |

+--------------------+

| information_schema |

| chat               |

| dede_kxdata        |

| dedecms            |

| dedecmsv57utf8sp1  |

| ecshop             |

| fikcdn             |

| hotel              |

| jpgraph            |

| kxdata             |

| myshop             |

| mysql              |

| newsreport         |

| notebook           |

| performance_schema |

| shop               |

| test               |

| testdb             |

| votedb             |

| #mysql50#          |

+--------------------+

20 rows in set, 1 warning (0.34 sec)

 

mysql> use information_schema;

Database changed

mysql> select a.table_schema as 'database_name'

    -> ,a.table_name as 'table_name'

    -> ,a.index_name as 'index1',

    -> b.index_name as 'index2',

    -> a.column_name as 'repeat_col'

    -> from statistics a join statistics b on

    -> a.table_schema=b.table_schema and a.table_name=b.table_name

    -> and a.seq_in_index=b.seq_in_index and a.column_name=b.column_name where

    -> a.seq_in_index=1 AND a.index_name<>b.index_name;

+-------------------+-------------------+---------+---------+------------+

| database_name     | table_name        | index1  | index2  | repeat_col |

+-------------------+-------------------+---------+---------+------------+

| dedecms           | dede_member_group | id      | PRIMARY | id         |

| dedecms           | dede_member_group | PRIMARY | id      | id         |

| dedecmsv57utf8sp1 | dede_member_group | id      | PRIMARY | id         |

| dedecmsv57utf8sp1 | dede_member_group | PRIMARY | id      | id         |

| kxdata            | dede_member_group | id      | PRIMARY | id         |

| kxdata            | dede_member_group | PRIMARY | id      | id         |

+-------------------+-------------------+---------+---------+------------+

6 rows in set (2.41 sec)

6.选择合适的数据类型

 7.反范式化

 3.页面静态化

利用ob缓存机制把php文件变为html文件

利用Smarty等视图模板引擎实现静态化