MySQL系列—8.存储结构
1.系统表空间 ibdata
系统表空间由参数innodb_data_file_path定义路径、初始化大小、自动扩展策略
如: innodb_data_file_path=/dayta/mysql/ibdata1:100M:autoextend
存放:
Change Buffer(insert buffer)
Lock System
Data Dictionary
Foreign key constaint system tables
User data (innodb_file_per_table=0,不使用独立表空间的时候,用户数据会存储共享表空 间中,有可能会存放在系统表空间。)
2.通用表空间 .ibd
类似于Oracle的表空间概念,多个Table放在同一个表空间中。
mysql> create tablespace tbs add datafile 'tbs.ibd';
Query OK, 0 rows affected (0.01 sec)mysql> select * from information_schema.innodb_tablespaces;
+------------+------------------+-------+----------------------+-----------+---------------+------------+---------------+-----------+----------------+-----------------+----------------+---------------+------------+--------+
| SPACE | NAME | FLAG | ROW_FORMAT | PAGE_SIZE | ZIP_PAGE_SIZE | SPACE_TYPE | FS_BLOCK_SIZE | FILE_SIZE | ALLOCATED_SIZE | AUTOEXTEND_SIZE | SERVER_VERSION | SPACE_VERSION | ENCRYPTION | STATE |
+------------+------------------+-------+----------------------+-----------+---------------+------------+---------------+-----------+----------------+-----------------+----------------+---------------+------------+--------+
| 4294967294 | mysql | 18432 | Any | 16384 | 0 | General | 4096 | 27262976 | 27262976 | 0 | 8.0.39 | 1 | N | normal |
| 4294967293 | innodb_temporary | 4096 | Compact or Redundant | 16384 | 0 | System | 4096 | 12582912 | 12582912 | 0 | 8.0.39 | 1 | N | normal |
| 4294967279 | innodb_undo_001 | 0 | Undo | 16384 | 0 | Undo | 4096 | 16777216 | 16777216 | 0 | 8.0.39 | 1 | N | active |
| 4294967278 | innodb_undo_002 | 0 | Undo | 16384 | 0 | Undo | 4096 | 16777216 | 16777216 | 0 | 8.0.39 | 1 | N | active |
| 1 | sys/sys_config | 16417 | Dynamic | 16384 | 0 | Single | 4096 | 114688 | 114688 | 0 | 8.0.39 | 1 | N | normal |
| 2 | tbs | 18432 | Any | 16384 | 0 | General | 4096 | 114688 | 114688 | 0 | 8.0.39 | 1 | N | normal |
+------------+------------------+-------+----------------------+-----------+---------------+------------+---------------+-----------+----------------+-----------------+----------------+---------------+------------+--------+
6 rows in set (0.00 sec)
mysql> create table t2 (id int) tablespace tbs;
Query OK, 0 rows affected (0.01 sec)
mysql> show create table t2;
+-------+---------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------+
| t2 | CREATE TABLE `t2` (`id` int DEFAULT NULL
) /*!50100 TABLESPACE `tbs` */ ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)
3.独立表空间
每个table都有各自的.ibd文件
删除大表的一个技巧(释放文件名)
为数据文件建立硬链接,然后删除原数据文件名,待到空闲时间再清理链接的文件数据
innodb_file_per_table
为1时(默认),启用独立表空间
为0时,启用共享表空间,用户数据存储在系统表空间ibdata*文件中,或者自定义的通用表空间general tablespace中。
为1时,启用独立表空间,每个表有各自的.ibd文件
4.Undo 表空间
实例初始化时,默认创建两个Undo表空间,最大支持127个Undo表空间。
innodb_rollback_segments:于定义每个undo表空间中的回滚段rollback segment的 数量,默认是128个
8.0.14后,可以在线手动创建新的Undo表空间
create undo tablespace undo_name add datafile 'undo_name.ibu';
一个回滚段rollback segment默认最大只有128 个,实例初始化后默认2个undo表空间:128*2个undo tbs= 256个并发事务。所以高并发需求 时需要注意增加undo表空间。
5.临时表空间
innodb_temp_data_file_path:定义路径、大小等,初始值12MB
实例关闭后,临时表文件会被删除,实例启动后,临时表文件(ibtmp1)重新创建
用户自己的临时表放在#innodb_temp/*.ibt,session会话退出后,临时段自动回收。
8.0以前, 有个严重问题,就是ibtmp1,用户执行过程中产生大量临时存在ibtmp1
文件被撑爆后也无法回缩的。
改进后只有innodb内部线程自己生成的临时表才会放在ibtmp1文件里。
用户运行过程中产生的临时表都会放在innodb_temp目录中
innodb_temp_tablespaces_dir:设置会话级用户临时表空间存储路径
会话级临时表空间初始共有10个,会随着用户连接数及创建临时表的情况按需增加,实例重 启后会删除这些文件。每个session最多分配两个临时表空间,一个用于存储用户主动创建的临时表(create temporary table),另一个用于存储用户执行SQL过程中生成的内部(磁盘)临时表,session断开后,会话级用户临时表空间会直接释放,不用再担心撑爆磁盘。
查看会话级临时表空间的使用情况:
select * from information_schema.innodb_session_temp_tablespaces;
查看全局临时表空间的情况:
select * from files where tablespace_name like '%temp%'\G
创建session级别临时表,通过实验来观察临时表的分配、查看及回收:
mysql> create temporary table k1 like bigints;
Query OK, 0 rows affected (0.04 sec)
mysql> desc k1;
+-------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+----------------+
| id | int | NO | PRI | NULL | auto_increment |
| dtl | varchar(200) | YES | | NULL | NULL |
+-------+--------------+------+-----+---------+----------------+
2 rows in set (0.02 sec)
mysql> insert into k1 select * from bigints;
Query OK, 2621440 rows affected (25.30 sec)
Records: 2621440 Duplicates: 0 Warnings: 0
--换一个session查询
mysql> select * from information_schema.innodb_temp_table_info;
+----------+--------------+--------+------------+
| TABLE_ID | NAME | N_COLS | SPACE |
+----------+--------------+--------+------------+
| 1089 | #sql4c_19_13 | 5 | 4294501264 |
+----------+--------------+--------+------------+
1 row in set (0.00 sec)
mysql> select * from information_schema.innodb_session_temp_tablespaces;
+----+------------+----------------------------+-----------+----------+-----
| ID | SPACE | PATH | SIZE | STATE | PURPOSE |
+----+------------+----------------------------+-----------+----------+-----
| 13 | 4294501265 | ./#innodb_temp/temp_9.ibt | 98304 | ACTIVE | INTRINSI
| 29 | 4294501263 | ./#innodb_temp/temp_7.ibt | 134217728 | ACTIVE | USER
| 0 | 4294501257 | ./#innodb_temp/temp_1.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501258 | ./#innodb_temp/temp_2.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501259 | ./#innodb_temp/temp_3.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501260 | ./#innodb_temp/temp_4.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501261 | ./#innodb_temp/temp_5.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501262 | ./#innodb_temp/temp_6.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501264 | ./#innodb_temp/temp_8.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501266 | ./#innodb_temp/temp_10.ibt | 81920 | INACTIVE | NONE
+----+------------+----------------------------+-----------+----------+-----
10 rows in set (0.00 sec)
[17:34:49] root@ms85:#innodb_temp # ll -h
total 129M
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_10.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_1.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_2.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_3.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_4.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_5.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_6.ibt
-rw-r----- 1 mysql mysql 128M Jul 7 17:35 temp_7.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 17:31 temp_8.ibt
-rw-r----- 1 mysql mysql 96K Jul 7 17:23 temp_9.ibt
--断开前一个session
mysql> exit;
Bye
--再次查询,发现临时表已经被释放
mysql> select * from information_schema.innodb_temp_table_info;
Empty set (0.00 sec)
mysql> select * from information_schema.innodb_session_temp_tablespaces;
+----+------------+----------------------------+-------+----------+---------
| ID | SPACE | PATH | SIZE | STATE | PURPOSE |
+----+------------+----------------------------+-------+----------+---------
| 12 | 4294501266 | ./#innodb_temp/temp_10.ibt | 81920 | ACTIVE | INTRINSIC
| 13 | 4294501265 | ./#innodb_temp/temp_9.ibt | 98304 | ACTIVE | INTRINSIC
| 0 | 4294501257 | ./#innodb_temp/temp_1.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501258 | ./#innodb_temp/temp_2.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501259 | ./#innodb_temp/temp_3.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501260 | ./#innodb_temp/temp_4.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501261 | ./#innodb_temp/temp_5.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501262 | ./#innodb_temp/temp_6.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501264 | ./#innodb_temp/temp_8.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501263 | ./#innodb_temp/temp_7.ibt | 81920 | INACTIVE | NONE |
+----+------------+----------------------------+-------+----------+---------
10 rows in set (0.00 sec
[17:36:08] root@ms85:#innodb_temp # ll
total 336K
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_10.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_1.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_2.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_3.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_4.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_5.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 11:39 temp_6.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 17:36 temp_7.ibt
-rw-r----- 1 mysql mysql 80K Jul 7 17:31 temp_8.ibt
-rw-r----- 1 mysql mysql 96K Jul 7 17:23 temp_9.ibt
干掉占用临时表空间的会话:
mysql> select * from information_schema.innodb_session_temp_tablespaces;
+----+------------+----------------------------+-----------+----------+-----
| ID | SPACE | PATH | SIZE | STATE | PURPOSE |
+----+------------+----------------------------+-----------+----------+-----
| 13 | 4294501265 | ./#innodb_temp/temp_9.ibt | 98304 | ACTIVE | INTRINSI
| 30 | 4294501263 | ./#innodb_temp/temp_7.ibt | 125829120 | ACTIVE | USER
| 0 | 4294501257 | ./#innodb_temp/temp_1.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501258 | ./#innodb_temp/temp_2.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501259 | ./#innodb_temp/temp_3.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501260 | ./#innodb_temp/temp_4.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501261 | ./#innodb_temp/temp_5.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501262 | ./#innodb_temp/temp_6.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501264 | ./#innodb_temp/temp_8.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501266 | ./#innodb_temp/temp_10.ibt | 81920 | INACTIVE | NONE
+----+------------+----------------------------+-----------+----------+-----
10 rows in set (0.00 sec)
mysql> show processlist;
+----+-----------------+-----------+--------------------+---------+-------+-
| Id | User | Host | db | Command | Time | State | In
+----+-----------------+-----------+--------------------+---------+-------+-
| 4 | event_scheduler | localhost | NULL | Daemon | 21518 | Waiting o
| 13 | root | localhost | information_schema | Query | 0 | starting
| 30 | root | localhost | kk | Query | 22 | executing |
+----+-----------------+-----------+--------------------+---------+-------+-
3 rows in set (0.00 sec)
mysql> kill 30
-> ;
Query OK, 0 rows affected (0.00 sec)
mysql> show processlist;
+----+-----------------+-----------+--------------------+---------+-------+-
| Id | User | Host | db | Command | Time | State | In
+----+-----------------+-----------+--------------------+---------+-------+-
| 4 | event_scheduler | localhost | NULL | Daemon | 21531 | Waiting o
| 13 | root | localhost | information_schema | Query | 0 | starting
+----+-----------------+-----------+--------------------+---------+-------+-
2 rows in set (0.00 sec)
mysql> select * from information_schema.innodb_session_temp_tablespaces;
+----+------------+----------------------------+-------+----------+---------
| ID | SPACE | PATH | SIZE | STATE | PURPOSE |
+----+------------+----------------------------+-------+----------+---------
| 13 | 4294501265 | ./#innodb_temp/temp_9.ibt | 98304 | ACTIVE | INTRINSIC
| 0 | 4294501257 | ./#innodb_temp/temp_1.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501258 | ./#innodb_temp/temp_2.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501259 | ./#innodb_temp/temp_3.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501260 | ./#innodb_temp/temp_4.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501261 | ./#innodb_temp/temp_5.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501262 | ./#innodb_temp/temp_6.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501264 | ./#innodb_temp/temp_8.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501266 | ./#innodb_temp/temp_10.ibt | 81920 | INACTIVE | NONE |
| 0 | 4294501263 | ./#innodb_temp/temp_7.ibt | 81920 | INACTIVE | NONE |
+----+------------+----------------------------+-------+----------+---------
10 rows in set (0.00 sec)