MySQL性能优化笔记整理

一.测试篇

1.测试目的,就是量化找出短板(基础参数配置)


2.测试三大指标
IOPS:每秒处理的IO请求数，即IO响应速度（注意和IO吞吐量的区别）
QPS:每秒请求（查询）次数
TPS:每秒事务数

3.测试工具
mysqlslap(略)
sysbench
tpcc-mysql 

二.mysql性能调优的思路

1.测试目的,就是量化找出短板(基础参数配置)


2.测试三大指标
IOPS:每秒处理的IO请求数，即IO响应速度（注意和IO吞吐量的区别）
QPS:每秒请求（查询）次数
TPS:每秒事务数

3.测试工具
mysqlslap(略)
sysbench
tpcc-mysql 

三.临时表的使用规则

1.测试目的,就是量化找出短板(基础参数配置)


2.测试三大指标
IOPS:每秒处理的IO请求数，即IO响应速度（注意和IO吞吐量的区别）
QPS:每秒请求（查询）次数
TPS:每秒事务数

3.测试工具
mysqlslap(略)
sysbench
tpcc-mysql 

四.表的优化与列类型选择

1.测试目的,就是量化找出短板(基础参数配置)


2.测试三大指标
IOPS:每秒处理的IO请求数，即IO响应速度（注意和IO吞吐量的区别）
QPS:每秒请求（查询）次数
TPS:每秒事务数

3.测试工具
mysqlslap(略)
sysbench
tpcc-mysql 

五.索引优化策略

多列索引上,索引发挥作用,需要满足左前缀要求.
以 index(a,b,c) 为例,
-----------------------------------------------------------------
语句                                   | 索引是否发挥作用
-----------------------------------------------------------------
Where a=3                               | 是,只使用了a列
Where a=3 and b=5                      | 是,使用了a,b列
Where a=3 and b=5 and c=4               | 是,使用了abc
Where b=3 / where c=4                   | 否
Where a=3 and c=4                       | a列能发挥索引,c不能
Where a=3 and b>10 and c=7             | A能利用,b能利用, C不能利用
where a=3 and b like ‘xxxx%’ and c=7 | A能用,B能用,C不能用
-----------------------------------------------------------------


假设某个表有一个联合索引（c1,c2,c3,c4）一下——只能使用该联合索引的c1,c2,c3部分
A where c1=x and c2=x and c4>x and c3=x 
B where c1=x and c2=x and c4=x order by c3
C where c1=x and c4= x group by c3,c2
D where c1=x and c5=x order by c2,c3
E where c1=x and c2=x and c5=? order by c2,c3

create table t4 (
c1 tinyint(1) not null default 0,
c2 tinyint(1) not null default 0,
c3 tinyint(1) not null default 0,
c4 tinyint(1) not null default 0,
c5 tinyint(1) not null default 0,
index c1234(c1,c2,c3,c4)
);
insert into t4 values (1,3,5,6,7),(2,3,9,8,3),(4,3,2,7,5);

对于A:
c1=x and c2=x and c4>x and c3=x  <==等价==> c1=x and c2=x and c3=x and c4>x
因此 c1,c2,c3,c4都能用上. 如下:
mysql> explain select * from t4 where c1=1 and c2=2 and c4>3 and c3=3 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: range
possible_keys: c1234
          key: c1234
      key_len: 4 #可以看出c1,c2,c3,c4索引都用上
          ref: NULL
         rows: 1
        Extra: Using where 

对于B: select * from t4 where c1=1 and c2=2 and c4=3 order by c3
c1 ,c2索引用上了,在c2用到索引的基础上,c3是排好序的,因此不用额外排序.
而c4没发挥作用.
mysql> explain select * from t4 where c1=1 and c2=2 and c4=3 order by c3 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 2
          ref: const,const
         rows: 1
        Extra: Using where
1 row in set (0.00 sec)

mysql> explain select * from t4 where c1=1 and c2=2 and c4=3 order by c5 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 2
          ref: const,const
         rows: 1
        Extra: Using where; Using filesort
1 row in set (0.00 sec)

对于 C: 只用到c1索引,因为group by c3,c2的顺序无法利用c2,c3索引
mysql> explain select * from t4 where c1=1 and c4=2 group by c3,c2 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 1 #只用到c1,因为先用c3后用c2分组,导致c2,c3索引没发挥作用
          ref: const
         rows: 1
        Extra: Using where; Using temporary; Using filesort
1 row in set (0.00 sec)

mysql> explain select * from t4 where c1=1 and c4=2 group by c2,c3 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 1
          ref: const
         rows: 1
        Extra: Using where
1 row in set (0.00 sec)

D语句: C1确定的基础上,c2是有序的,C2之下C3是有序的,因此c2,c3发挥的排序的作用.
因此,没用到filesort
mysql> explain select * from t4 where c1=1 and c5=2 order by c2,c3 \G  
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 1
          ref: const
         rows: 1
        Extra: Using where
1 row in set (0.00 sec)

E: 这一句等价与 elect * from t4 where c1=1 and c2=3 and c5=2 order by c3; 
因为c2的值既是固定的,参与排序时并不考虑

mysql> explain select * from t4 where c1=1 and c2=3 and c5=2 order by c2,c3 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 2
          ref: const,const
         rows: 1
        Extra: Using where
1 row in set (0.00 sec)

六.聚簇索引与非聚簇索引

多列索引上,索引发挥作用,需要满足左前缀要求.
以 index(a,b,c) 为例,
-----------------------------------------------------------------
语句                                   | 索引是否发挥作用
-----------------------------------------------------------------
Where a=3                               | 是,只使用了a列
Where a=3 and b=5                      | 是,使用了a,b列
Where a=3 and b=5 and c=4               | 是,使用了abc
Where b=3 / where c=4                   | 否
Where a=3 and c=4                       | a列能发挥索引,c不能
Where a=3 and b>10 and c=7             | A能利用,b能利用, C不能利用
where a=3 and b like ‘xxxx%’ and c=7 | A能用,B能用,C不能用
-----------------------------------------------------------------


假设某个表有一个联合索引（c1,c2,c3,c4）一下——只能使用该联合索引的c1,c2,c3部分
A where c1=x and c2=x and c4>x and c3=x 
B where c1=x and c2=x and c4=x order by c3
C where c1=x and c4= x group by c3,c2
D where c1=x and c5=x order by c2,c3
E where c1=x and c2=x and c5=? order by c2,c3

create table t4 (
c1 tinyint(1) not null default 0,
c2 tinyint(1) not null default 0,
c3 tinyint(1) not null default 0,
c4 tinyint(1) not null default 0,
c5 tinyint(1) not null default 0,
index c1234(c1,c2,c3,c4)
);
insert into t4 values (1,3,5,6,7),(2,3,9,8,3),(4,3,2,7,5);

对于A:
c1=x and c2=x and c4>x and c3=x  <==等价==> c1=x and c2=x and c3=x and c4>x
因此 c1,c2,c3,c4都能用上. 如下:
mysql> explain select * from t4 where c1=1 and c2=2 and c4>3 and c3=3 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: range
possible_keys: c1234
          key: c1234
      key_len: 4 #可以看出c1,c2,c3,c4索引都用上
          ref: NULL
         rows: 1
        Extra: Using where 

对于B: select * from t4 where c1=1 and c2=2 and c4=3 order by c3
c1 ,c2索引用上了,在c2用到索引的基础上,c3是排好序的,因此不用额外排序.
而c4没发挥作用.
mysql> explain select * from t4 where c1=1 and c2=2 and c4=3 order by c3 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 2
          ref: const,const
         rows: 1
        Extra: Using where
1 row in set (0.00 sec)

mysql> explain select * from t4 where c1=1 and c2=2 and c4=3 order by c5 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 2
          ref: const,const
         rows: 1
        Extra: Using where; Using filesort
1 row in set (0.00 sec)

对于 C: 只用到c1索引,因为group by c3,c2的顺序无法利用c2,c3索引
mysql> explain select * from t4 where c1=1 and c4=2 group by c3,c2 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 1 #只用到c1,因为先用c3后用c2分组,导致c2,c3索引没发挥作用
          ref: const
         rows: 1
        Extra: Using where; Using temporary; Using filesort
1 row in set (0.00 sec)

mysql> explain select * from t4 where c1=1 and c4=2 group by c2,c3 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 1
          ref: const
         rows: 1
        Extra: Using where
1 row in set (0.00 sec)

D语句: C1确定的基础上,c2是有序的,C2之下C3是有序的,因此c2,c3发挥的排序的作用.
因此,没用到filesort
mysql> explain select * from t4 where c1=1 and c5=2 order by c2,c3 \G  
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 1
          ref: const
         rows: 1
        Extra: Using where
1 row in set (0.00 sec)

E: 这一句等价与 elect * from t4 where c1=1 and c2=3 and c5=2 order by c3; 
因为c2的值既是固定的,参与排序时并不考虑

mysql> explain select * from t4 where c1=1 and c2=3 and c5=2 order by c2,c3 \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t4
         type: ref
possible_keys: c1234
          key: c1234
      key_len: 2
          ref: const,const
         rows: 1
        Extra: Using where
1 row in set (0.00 sec)