019：InnoDB 表空间内部组织结构

mysql> select * from information_schema.innodb_sys_tables limit 1\G ;  -- INNODB_SYS_TABLES 表
*************************** 1. row ***************************
   TABLE_ID: 14
       NAME: SYS_DATAFILES
       FLAG: 0
     N_COLS: 5
      SPACE: 0
FILE_FORMAT: Antelope
 ROW_FORMAT: Redundant
ZIP_PAGE_SIZE: 0
 SPACE_TYPE: System
1 row in set (0.01 sec)

mysql>select name, space,table_id from information_schema.innodb_sys_tables where space=0 ;
+------------------+-------+----------+
| name             | space | table_id |
+------------------+-------+----------+
| SYS_DATAFILES    |     0 |       14 |
| SYS_FOREIGN      |     0 |       11 |
| SYS_FOREIGN_COLS |     0 |       12 |
| SYS_TABLESPACES  |     0 |       13 |
| SYS_VIRTUAL      |     0 |       15 |
+------------------+-------+----------+
5 rows in set (0.01 sec)
mysql> select name, space,table_id from information_schema.innodb_sys_tables where space<>0 limit 5 ;
+-----------------------------+-------+----------+
| name                        | space | table_id |
+-----------------------------+-------+----------+
| employees/departments       |    32 |       47 |
| employees/dept_emp          |    34 |       49 |
| employees/dept_manager      |    33 |       48 |
| employees/employee_comps_1  |    48 |       63 |
| employees/employee_comps_2k |    50 |       65 |
+-----------------------------+-------+----------+
5 rows in set (0.00 sec)        

--  独立表空间的table_id 和 SpaceID 一一对应
--  共享表空间是多个table_id 对应 一个 SpaceID

-- ger3_space的file_block_size=4096，不是innodb_page_size的大小
-- 所在在创建 普通表 的时候，报错了

mysql> create table  test_ger (a int) tablespace=ger3_space;
ERROR 1478 (HY000): InnoDB: Tablespace `ger3_space` uses block size 4096 and cannot contain a table with physical page size 8192
-- 使用压缩表的方式

mysql> create table comps_test1 (a int) row_format=compressed, key_block_size=4; -- 1K, 2K, 4K, 8K, 16K 只有这几个页大小可以选择

Query OK, 0 rows affected (0.13 sec)
-- 在之前的ger3_space中创建压缩表

mysql> create table comps_test2 (a int)tablespace=ger3_space row_format=compressed, key_block_size=4;
-- 由于ger3_space是4K的，所以这里页大小也只能是4K Query OK, 0 rows affected (0.09 sec)
-- 修改存在的表变成压缩表

mysql> alter table t1 row_format=compressed,key_block_size=4; Query OK, 0 rows affected (0.17 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> use employees ; 
Database changed

mysql>  create table employee_comps_1 like employees;
Query OK, 0 rows affected

mysql> alter table employee_comps_1 row_format=compressed,key_block_size=4;
Query OK, 0 rows affected


mysql> >  show create table employee_comps_1\G
*************************** 1. row ***************************
     Table: employee_comps_1
Create Table: CREATE TABLE `employee_comps_1` (
`emp_no` int(11) NOT NULL,
`birth_date` date NOT NULL,
`first_name` varchar(14) NOT NULL,
`last_name` varchar(16) NOT NULL,
`gender` enum('M','F') NOT NULL,
`hire_date` date NOT NULL,
PRIMARY KEY (`emp_no`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=4
1 row in set (0.00 sec)

-- 插入数据                                             
mysql> insert into employee_comps_1 select * from employees;
Query OK, 300024 rows affected (6.65 sec)                       
Records: 300024  Duplicates:    0   Warnings: 0                         
-- 查看压缩比                                                
mysql> use information_schema;                              
Reading table information for completion of table and column names              
You can turn off this feature to get a quicker startup with -A              
Database changed                                        
mysql>select * from INNODB_CMP;
+-----------+--------------+-----------------+---------------+----------------+-----------------+
| page_size | compress_ops | compress_ops_ok | compress_time | uncompress_ops | uncompress_time |
+-----------+--------------+-----------------+---------------+----------------+-----------------+
|      1024 |            0 |               0 |             0 |              0 |               0 |
|      2048 |            0 |               0 |             0 |              0 |               0 |
|      4096 |        18599 |           13442 |             2 |           5157 |               0 |
|      8192 |            0 |               0 |             0 |              0 |               0 |
|     16384 |            0 |               0 |             0 |              0 |               0 |
+-----------+--------------+-----------------+---------------+----------------+-----------------+
5 rows in set (0.01 sec)

mysql> select 13442/18599;  -- compress_ops_ok / compress_ops       
+-------------+
| 13442/18599 |
+-------------+
|      0.7227 |    -- 压缩比在90%
+-------------+
1 row in set (0.00 sec)

mysql> select * from INNODB_CMP_RESET;                          
-- 查询INOODB_CMP_RESET，会把INNODB_CMP表中的数据复制过来，并清空INNODB_CMP               
+-----------+--------------+-----------------+---------------+----------------+-----------------+
| page_size | compress_ops | compress_ops_ok | compress_time | uncompress_ops | uncompress_time |
+-----------+--------------+-----------------+---------------+----------------+-----------------+
|      1024 |            0 |               0 |             0 |              0 |               0 |
|      2048 |            0 |               0 |             0 |              0 |               0 |
|      4096 |        18599 |           13442 |             2 |           5157 |               0 |
|      8192 |            0 |               0 |             0 |              0 |               0 |
|     16384 |            0 |               0 |             0 |              0 |               0 |
+-----------+--------------+-----------------+---------------+----------------+-----------------+
5 rows in set (0.00 sec)                                    
mysql> select   * from INNODB_CMP;  -- 查询该表，数据已经被清空了                        
+-----------+--------------+-----------------+---------------+----------------+-----------------+
| page_size | compress_ops | compress_ops_ok | compress_time | uncompress_ops | uncompress_time |
+-----------+--------------+-----------------+---------------+----------------+-----------------+
|      1024 |            0 |               0 |             0 |              0 |               0 |
|      2048 |            0 |               0 |             0 |              0 |               0 |
|      4096 |            0 |               0 |             0 |              0 |               0 |
|      8192 |            0 |               0 |             0 |              0 |               0 |
|     16384 |            0 |               0 |             0 |              0 |               0 |
+-----------+--------------+-----------------+---------------+----------------+-----------------+
5 rows in set (0.00 sec)                                    

-- 注意，这个表里面的数据是累加的，是全局信息，没法对应到某一张表

shell> ll -h employee*.ibd  # 可以看出磁盘占用还是有明显减小的

-rw-r-----. 1 mysql mysql 14M Jan  4 13:41 employee_comps_1.ibd

-rw-r-----. 1 mysql mysql 22M Dec  2 21:32 employees.ibd

mysql> show variables like "%innodb_cmp_per_index%";

+------------------------------+-------+
| Variable_name                | Value |
+------------------------------+-------+
| innodb_cmp_per_index_enabled | OFF   | -- 该功能目前是关闭的
+------------------------------+-------+
1 row in set (0.02 sec)


mysql> set global innodb_cmp_per_index_enabled=1; 
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like "%innodb_cmp_per_index%";

+------------------------------+-------+
| Variable_name                | Value |
+------------------------------+-------+
| innodb_cmp_per_index_enabled | ON    |
+------------------------------+-------+
1 row in set (0.01 sec)     


mysql> use employees

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A


Database changed

mysql> create table employee_comps_2k like employees; 
Query OK, 0 rows affected (0.13 sec)

mysql> alter table employee_comps_2k row_format=compressed,key_block_size=2;  -- 设置成2K的页大小

Query OK, 0 rows affected (0.18 sec)

Records: 0  Duplicates: 0  Warnings: 0


mysql> insert into employee_comps_2k select * from employees; -- 插入数据

Query OK, 300024 rows affected (9.68 sec)

Records: 300024  Duplicates: 0  Warnings: 0


mysql> use information_schema;

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A


Database changed                                    
mysql> select * from INNODB_CMP;                                
+-----------+--------------+-----------------+---------------+----------------+-----------------+
| page_size | compress_ops | compress_ops_ok | compress_time | uncompress_ops | uncompress_time |
+-----------+--------------+-----------------+---------------+----------------+-----------------+
|      1024 |            0 |               0 |             0 |              0 |               0 |
|      2048 |        34676 |           23729 |             2 |          10947 |               0 |
|      4096 |            0 |               0 |             0 |              0 |               0 |
|      8192 |            0 |               0 |             0 |              0 |               0 |
|     16384 |            0 |               0 |             0 |              0 |               0 |
+-----------+--------------+-----------------+---------------+----------------+-----------------+
5 rows in set (0.01 sec)    

mysql> select   23729/34676;                                    
+-------------+
| 23729/34676 |
+-------------+
|      0.6843 | -- 2K时，压缩比是68%
+-------------+
1 row in set (0.01 sec)                                 

mysql> select * from INNODB_CMP_PER_INDEX;  -- 开启innodb_cmp_per_index_enabled才有数据                   
+---------------+-------------------+------------+--------------+-----------------+---------------+----------------+-----------------+
| database_name | table_name        | index_name | compress_ops | compress_ops_ok | compress_time | uncompress_ops | uncompress_time |
+---------------+-------------------+------------+--------------+-----------------+---------------+----------------+-----------------+
| employees     | employee_comps_2k | PRIMARY    |        34676 |           23729 |             2 |          10947 |               0 |
+---------------+-------------------+------------+--------------+-----------------+---------------+----------------+-----------------+
1 row in set (0.00 sec) 

-- 可以看到employees.employee_comps_2k这个表的 索引的压缩比（在INNODB中索引即数据）；
-- 在page_size=2K只有一个压缩表的时候，INNODB_CMP和INNODB_CMP_PER_INDEX的值是一样的，并且能够知道是哪个表的情况

-- 透明表空间压缩的创建
mysql> create table trans_test_1 (a int ) compression="zlib"; -- 使用zlib的压缩算法
Query OK, 0 rows affected, 1 warning (0.14 sec) -- 存在warning
mysql> create table trans_test_2 (a int ) compression="lz4"; -- 使用lz4的压缩算法
Query OK, 0 rows affected, 1 warning (0.13 sec)
mysql> alter table trans_test_2 compression="zlib";
Query OK, 0 rows affected (0.05 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> optimize table trans_test_2; -- 官方文档中提及如果是已存在的表，需要执行optimize table操作
+------------------------+----------+----------+-------------------------------------------------------------------+
| Table | Op | Msg_type | Msg_text |
+------------------------+----------+----------+-------------------------------------------------------------------+
| burn_test.trans_test_2 | optimize | note | Table does not support optimize, doing recreate + analyze instead |
| burn_test.trans_test_2 | optimize | status | OK |
+------------------------+----------+----------+-------------------------------------------------------------------+
2 rows in set, 1 warning (0.18 sec) -- 还是有warning
mysql> show create table trans_test_1\G
*************************** 1. row ***************************
Table: trans_test_1
Create Table: CREATE TABLE `trans_test_1` (
`a` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMPRESSION='zlib'
1 row in set (0.00 sec)
-- zlib的压缩比更高
-- lz4的速度更快
在上述创建过程中，并 没有指定页大小 ，而是使用了文件系统（filesystem）层中 稀疏文件 的特性，来达到压缩的目的。

# 创建一个零时的，且数据部分全0的文件
shell> dd of=sparse-file bs=1k seek=5120 count=0 # 创建5M大小，内容全为0的文件
0+0 records in
0+0 records out
0 bytes (0 B) copied, 6.7872e-05 s, 0.0 kB/s # 无数据写入到磁盘
shell> ls -hl sparse-file 
-rw-r--r--. 1 root root 5.0M Jan 5 00:07 sparse-file # 显示该文件大小为5M
shell> du --block-size=1 sparse-file # 检查文件占用多少空间
0 sparse-file # 显示占用空间为0

mysql> desc information_schema.INNODB_SYS_TABLESPACES;
+----------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------------+---------------------+------+-----+---------+-------+
| SPACE | int(11) unsigned | NO | | 0 | |
| NAME | varchar(655) | NO | | | |
| FLAG | int(11) unsigned | NO | | 0 | |
| FILE_FORMAT | varchar(10) | YES | | NULL | |
| ROW_FORMAT | varchar(22) | YES | | NULL | |
| PAGE_SIZE | int(11) unsigned | NO | | 0 | |
| ZIP_PAGE_SIZE | int(11) unsigned | NO | | 0 | |
| SPACE_TYPE | varchar(10) | YES | | NULL | |
| FS_BLOCK_SIZE | int(11) unsigned | NO | | 0 | | -- 文件系统的块大小
| FILE_SIZE | bigint(21) unsigned | NO | | 0 | | -- 文件大小
| ALLOCATED_SIZE | bigint(21) unsigned | NO | | 0 | | -- 文件实际分配的大小
| COMPRESSION | varchar(5) | NO | | | |
+----------------+---------------------+------+-----+---------+-------+
12 rows in set (0.00 sec)

mysql> show warnings;
+---------+------+---------------------------------------------------------------------------------------------------------------------------+
| Level | Code | Message |
+---------+------+---------------------------------------------------------------------------------------------------------------------------+
| Warning | 138 | InnoDB: Punch hole not supported by the file system or the tablespace page size is not large enough. Compression disabled |
+---------+------+---------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

-- 原因1是我的内核版本太低，不支持
-- 原因2是因为general方式安装的mysql不支持透明压缩，需要自己编译
-- http://bugs.mysql.com/bug.php?id=77974

mysql> create table test_key (
 -> a int,
 -> b int not null,
 -> c int not null,
 -> unique key(a),
 -> unique key(c),
 -> unique key(b)
 -> );
Query OK, 0 rows affected (0.16 sec)
mysql> insert into test_key values(1,2,3),(4,5,6),(7,8,9);
Query OK, 3 rows affected (0.04 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select * from test_key;
+------+---+---+
| a | b | c |
+------+---+---+
| 1 | 2 | 3 |
| 4 | 5 | 6 |
| 7 | 8 | 9 |
+------+---+---+
3 rows in set (0.00 sec)
mysql> select *, _rowid from test_key; -- _rowid是主键值
+------+---+---+--------+
| a | b | c | _rowid |
+------+---+---+--------+
| 1 | 2 | 3 | 3 | -- 可以发现，这里的主键是c
| 4 | 5 | 6 | 6 |
| 7 | 8 | 9 | 9 |
+------+---+---+--------+
3 rows in set (0.00 sec)
mysql> create table test_key_2 (
 -> a varchar(8), -- 使用varchar类型
 -> b varchar(8) not null,
 -> c varchar(8) not null,
 -> unique key(a),
 -> unique key(c),
 -> unique key(b)
 -> );
Query OK, 0 rows affected (0.15 sec)
mysql> insert into test_key_2 values('a','b','c'),('d','e','f'),('g','h','i');
Query OK, 3 rows affected (0.02 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select * from test_key_2; 
+------+---+---+
| a | b | c |
+------+---+---+
| a | b | c |
| d | e | f |
| g | h | i |
+------+---+---+
3 rows in set (0.00 sec)
mysql> select *, _rowid from test_key_2;
ERROR 1054 (42S22): Unknown column '_rowid' in 'field list' -- 报错了
-- _rowid只能是在key的类型为整型时才有效

-- 方法一

mysql> select * from information_schema.columns where table_name="test_key_2" and column_key="PRI"\G
*************************** 1. row ***************************
 TABLE_CATALOG: def
 TABLE_SCHEMA: burn_test
 TABLE_NAME: test_key_2
 COLUMN_NAME: c -- 该列的列名是 c
 ORDINAL_POSITION: 3
 COLUMN_DEFAULT: NULL
 IS_NULLABLE: NO
 DATA_TYPE: varchar
CHARACTER_MAXIMUM_LENGTH: 8
 CHARACTER_OCTET_LENGTH: 32
 NUMERIC_PRECISION: NULL
 NUMERIC_SCALE: NULL
 DATETIME_PRECISION: NULL
 CHARACTER_SET_NAME: utf8mb4
 COLLATION_NAME: utf8mb4_general_ci
 COLUMN_TYPE: varchar(8)
 COLUMN_KEY: PRI -- 该列是主键
 EXTRA: 
PRIVILEGES: select,insert,update,references
 COLUMN_COMMENT: 
 GENERATION_EXPRESSION: 
1 row in set (0.00 sec)

-- 方法二

mysql> desc test_key_2;
+-------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------------+------+-----+---------+-------+
| a | varchar(8) | YES | UNI | NULL | |
| b | varchar(8) | NO | UNI | NULL | |
| c | varchar(8) | NO | PRI | NULL | | -- key 是PRI ，就可以知道 c 列是主键
+-------+------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql> create table test_key_3(
 -> a int,
 -> b int,
 -> c int);
Query OK, 0 rows affected (0.11 sec)
mysql> insert into test_key_3 values(1,2,3),(4,5,6),(7,8,9);
Query OK, 3 rows affected (0.02 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select *,_rowid from test_key_3; 
ERROR 1054 (42S22): Unknown column '_rowid' in 'field list' --这里无法用_rowid查看，因为系统rowid对用户是透明的

mysql> create table test_heap(a int primary key); Query OK, 0 rows affected (0.13 sec)

mysql> insert into test_heap values (1);  -- 插入a=1的记录

Query OK, 1 row affected (0.03 sec)


mysql> begin;  -- 开启事物

Query OK, 0 rows affected (0.00 sec)


mysql> delete from test_heap where a=1;  -- 删除a=1的记录，此时加上了锁

Query OK, 1 row affected (0.00 sec)

mysql>mysql> show variables like "%innodb_status_output_locks%";

+----------------------------   +   -------+
| Variable_name |   Value |
+----------------------------   +   -------+
| innodb_status_output_locks |  OFF  |
+----------------------------   +   -------+


mysql> set global innodb_status_output_locks=1; Query OK, 0 rows affected (0.00 sec)

mysql> pager less -- 使用类似linux中的less命令方式进行查看，可上下翻页

PAGER set to 'less'


mysql> show engine innodb status\G

-- -----------省略其他输出-------------

TABLE LOCK table `burn_test`.`test_heap` trx id 16943 lock mode IX

RECORD LOCKS space id 122 page no 3 n bits 72 index PRIMARY of table `burn_test`.`test_heap` trx id 16943 lock_mode X locks rec but not gap Record lock, heap no 2 PHYSICAL RECORD: n_fields 3; compact format; info bits 32

0: len 4; hex 80000001; asc ;;  -- 插入的主键a=1，8的二进制1000，最高位为1，表示有符号的

1: len 6; hex 00000000422f; asc B/;;  -- 0x422f的 十进制就是16943 ，表示事物id（trx id）

2: len 7; hex 2c000000450dcf; asc , E  ;;  -- roll pointer（回滚指针）

--  -----------省略其他输出-------------

--  space id 122  : 表空间id是122
--  page no 3    : 对应的页号是3 （表示第4个页，是root页）
--  heap no 2    : heap number是2 （表示是新插入的第一条记录）
--  heap no = 1 的一种情况

-- 终端1

mysql> rollback;

Query OK, 0 rows affected (0.00 sec)


mysql> set tx_isolation='repeatable-read'; Query OK, 0 rows affected (0.00 sec)

mysql> select * from test_heap where a>1 for update; Empty set (0.00 sec)

-- 终端2

mysql> show engine innodb status\G

-- -----------省略其他输出-------------

Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0

0: len 8; hex 73757072656d756d; asc supremum;;  -- 一条伪记录


Record lock, heap no 2 PHYSICAL RECORD: n_fields 3; compact format; info bits 0

0: len 4;   hex 80000001; asc   ;;  
1: len  6;  hex 00000000422e; asc       B.;;
2: len  7;  hex ab000000470110; asc G  ;;

-- -----------省略其他输出-------------