MySQL高级篇（存储引擎InnoDB、MyISAM、Memory）

目录

1、存储引擎简介

1.1、查询建表语句，默认存储引擎：InnoDB

1.2、查看当前数据库支持的存储引擎

1.3、创建表，并指定存储引擎

2、存储引擎-InnoDB介绍

2.1、存储引擎特点

3、MyISAM存储引擎

4、Memory存储引擎

5、InnoDB、MyISAM、Memory的区别

6、存储引擎的选择

1、存储引擎简介

1.1、查询建表语句，默认存储引擎：InnoDB
-- 查询建表语句
show create table emp;

1.2、查看当前数据库支持的存储引擎
-- 查看当前数据库支持的存储引擎
show engines;

1.3、创建表，并指定存储引擎

-- 创建表 my_myisam,并指定MYISAM存储引擎
create table my_myisam
(id   int,name varchar(10)
) engine = MyISAM;-- 创建表 my_memory,指定MEMORY存储引擎
create table my_memory
(id   int,name varchar(10)
) engine = MEMORY;

2、存储引擎-InnoDB介绍

2.1、存储引擎特点

介绍：InnoDB是一种兼顾高可靠性和高性能的通用存储引擎，在MySQL 5.5之后，InnoDB是默认的MySQL存储引擎。
特点：DML操作遵循ACID 原子性（Atomicity）、一致性（Consistency）、隔离性（Isolation）和持久性（Durability）模型，支持事务；行级锁，提高并发访问性能；支持外键 FOREIGN KEY约束，保证数据的完整性和正确性；
文件：xxx.ibd：xxx代表的是表名，InnoDB引擎的每张表都会对应这样一个表空间文件，存储该表的表结构（frm、sdi）、数据和索引。参数：innodb_file_per_table
在InnoDB存储引擎中，.ibd文件是表空间文件，用于存储表的数据和索引。每个InnoDB表都有一个与之关联的.ibd文件（除非该表被配置为使用共享表空间）。.ibd文件通常包含表的元数据、数据和索引信息。

当InnoDB存储引擎的innodb_file_per_table配置选项被启用时，每个InnoDB表都会有自己独立的.ibd文件。这样做的好处是，可以更容易地管理单个表的大小和存储位置，例如，可以通过移动或删除.ibd文件来移动或删除表。

与.ibd文件相对应的是.frm文件，它存储了表的元数据（即表结构）。而InnoDB的系统表空间文件通常命名为ibdata1、ibdata2等，用于存储undo日志、插入缓冲区、锁信息等。

在某些情况下，例如当表损坏或需要优化时，可能需要直接操作.ibd文件。但是，直接操作这些文件是危险的，应该谨慎进行，并在操作前备份相关数据。

show variables like 'innodb_file_per_table';

C:\ProgramData\MySQL\MySQL Server 8.0\Data

Microsoft Windows [版本 10.0.19045.3996]
(c) Microsoft Corporation。保留所有权利。C:\ProgramData\MySQL\MySQL Server 8.0\Data\mybatis@002dexample>ibd2sdi t_book.ibd
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