七十四、【Linux数据库】MySQL数据库存储引擎

MySQL 存储引擎功能概述

核心功能

1. 数据存储格式：定义数据在磁盘上的物理存储方式
2. 事务支持：ACID 特性保证数据一致性
3. 锁机制：控制并发访问的锁策略
4. 索引结构：实现高效数据检索
5. 崩溃恢复：故障后自动恢复数据一致性

引擎对比

特性	InnoDB	MyISAM	Memory	Archive
事务支持	✓	✗	✗	✗
行级锁	✓	✗	✗	✗
外键约束	✓	✗	✗	✗
崩溃恢复	✓	✗	✗	✗
全文索引	✓ (5.6+)	✓	✗	✗
存储限制	64TB	256TB	RAM大小	无限制
适用场景	OLTP	只读分析	临时缓存	日志归档

---

一、存储引擎操作演示

1. 查看存储引擎

# 登录MySQL
[root@localhost ~]# mysql -u root -p
Enter password: ******# 查看支持的引擎
mysql> SHOW ENGINES;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine             | Support | Comment                                                        | Transactions | XA   | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| MyISAM             | YES     | MyISAM storage engine                                          | NO           | NO   | NO         |
| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |
| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+# 查看当前默认引擎
mysql> SELECT @@default_storage_engine;
+--------------------------+
| @@default_storage_engine |
+--------------------------+
| InnoDB                   |
+--------------------------+

2. 创建表指定引擎

# 创建InnoDB表
mysql> CREATE TABLE innodb_tbl (id INT PRIMARY KEY,data VARCHAR(100)
) ENGINE=InnoDB;# 创建MyISAM表
mysql> CREATE TABLE myisam_tbl (id INT PRIMARY KEY,data VARCHAR(100)
) ENGINE=MyISAM;# 创建Memory表
mysql> CREATE TABLE memory_tbl (id INT PRIMARY KEY,data VARCHAR(100)
) ENGINE=MEMORY;

3. 修改表引擎

# 修改为InnoDB
mysql> ALTER TABLE myisam_tbl ENGINE=InnoDB;# 修改为MyISAM
mysql> ALTER TABLE innodb_tbl ENGINE=MyISAM;

4. 查看表引擎信息

mysql> SHOW TABLE STATUS LIKE 'innodb_tbl'\G
*************************** 1. row ***************************Name: innodb_tblEngine: InnoDBVersion: 10Row_format: DynamicRows: 0Avg_row_length: 0Data_length: 16384
Max_data_length: 0Index_length: 0Data_free: 0Auto_increment: NULLCreate_time: 2023-06-15 14:30:05Update_time: NULLCheck_time: NULLCollation: utf8mb4_general_ciChecksum: NULLCreate_options: Comment: 

---

二、引擎特性演示

1. InnoDB 事务演示

# 开启事务
mysql> START TRANSACTION;
mysql> INSERT INTO innodb_tbl VALUES (1, 'Transaction test');# 回滚事务
mysql> ROLLBACK;# 验证数据未提交
mysql> SELECT * FROM innodb_tbl;
Empty set (0.00 sec)

2. MyISAM 表修复

# 模拟表损坏
[root@localhost ~]# dd if=/dev/zero of=/var/lib/mysql/test/myisam_tbl.MYD bs=1 count=100# 检查表状态
mysql> CHECK TABLE myisam_tbl;
+-------------------+-------+----------+----------------------------------------------------+
| Table             | Op    | Msg_type | Msg_text                                           |
+-------------------+-------+----------+----------------------------------------------------+
| test.myisam_tbl   | check | Error    | Corrupt                                            |
+-------------------+-------+----------+----------------------------------------------------+# 修复表
mysql> REPAIR TABLE myisam_tbl;
+-------------------+--------+----------+----------------------------------------------------+
| Table             | Op     | Msg_type | Msg_text                                           |
+-------------------+--------+----------+----------------------------------------------------+
| test.myisam_tbl   | repair | status   | OK                                                 |
+-------------------+--------+----------+----------------------------------------------------+

3. Memory 引擎特性

# 插入数据
mysql> INSERT INTO memory_tbl VALUES (1, 'Memory data');# 重启MySQL服务
[root@localhost ~]# systemctl restart mysqld# 验证数据丢失
mysql> SELECT * FROM memory_tbl;
Empty set (0.00 sec)

4. Archive 引擎压缩

# 创建Archive表
mysql> CREATE TABLE archive_tbl (id INT,log TEXT
) ENGINE=ARCHIVE;# 插入数据
mysql> INSERT INTO archive_tbl VALUES (1, REPEAT('Log entry ', 1000));# 查看文件大小
[root@localhost ~]# ls -lh /var/lib/mysql/test/archive_tbl.ARZ
-rw-r----- 1 mysql mysql 2.5K Jun 15 15:00 archive_tbl.ARZ

---

三、性能对比测试

1. 插入性能测试

# 创建测试表
mysql> CREATE TABLE insert_test_innodb (id INT) ENGINE=InnoDB;
mysql> CREATE TABLE insert_test_myisam (id INT) ENGINE=MyISAM;# 批量插入测试
mysql> SET profiling=1;
mysql> INSERT INTO insert_test_innodb SELECT * FROM seq_1_to_1000000;
mysql> INSERT INTO insert_test_myisam SELECT * FROM seq_1_to_1000000;
mysql> SHOW PROFILES;
+----------+------------+----------------------------------------------------+
| Query_ID | Duration   | Query                                              |
+----------+------------+----------------------------------------------------+
|        1 | 5.23148200 | INSERT INTO insert_test_innodb SELECT ...          |
|        2 | 3.87654100 | INSERT INTO insert_test_myisam SELECT ...          |
+----------+------------+----------------------------------------------------+

2. 查询性能测试

# 创建索引
mysql> ALTER TABLE insert_test_innodb ADD INDEX idx_id(id);
mysql> ALTER TABLE insert_test_myisam ADD INDEX idx_id(id);# 范围查询测试
mysql> SELECT COUNT(*) FROM insert_test_innodb WHERE id BETWEEN 1000 AND 2000;
1 row in set (0.15 sec)mysql> SELECT COUNT(*) FROM insert_test_myisam WHERE id BETWEEN 1000 AND 2000;
1 row in set (0.08 sec)

---

命令总结表格

演示命令	功能描述	关键参数
SHOW ENGINES	查看支持引擎	无
SELECT @@default_storage_engine	查看默认引擎	无
CREATE TABLE t (...) ENGINE=InnoDB	指定引擎创建表	ENGINE=
ALTER TABLE t ENGINE=InnoDB	修改表引擎	ENGINE=
SHOW TABLE STATUS LIKE 't'	查看表引擎信息	表名
START TRANSACTION	开始事务	无
ROLLBACK	回滚事务	无
REPAIR TABLE t	修复MyISAM表	表名
SET profiling=1	启用性能分析	无
SHOW PROFILES	查看查询性能	无

---

功能作用详解

1. InnoDB 深度解析

核心特性

关键配置

# my.cnf 配置
innodb_buffer_pool_size=物理内存的70-80%
innodb_log_file_size=缓冲池的25%
innodb_flush_log_at_trx_commit=1  # 完全持久化

2. MyISAM 适用场景

优势场景

1. 全文本搜索：MATCH AGAINST 操作
2. 数据仓库：只读或读密集型操作
3. 空间数据：GIS 空间索引支持

维护命令

# 优化表（碎片整理）
OPTIMIZE TABLE myisam_tbl;# 修复索引
REPAIR TABLE myisam_tbl QUICK;

3. Memory 引擎限制

使用注意事项

1. 数据丢失：服务重启后数据清空
2. 表大小限制：max_heap_table_size 控制
3. 不支持BLOB/TEXT：只支持定长数据类型

临时表优化

-- 显式创建临时表
CREATE TEMPORARY TABLE temp_data ENGINE=MEMORY SELECT * FROM large_table;

4. 其他引擎应用

CSV 引擎

-- 创建CSV表
CREATE TABLE csv_data (id INT,name VARCHAR(50)
) ENGINE=CSV;-- 外部数据导入
LOAD DATA INFILE '/data/import.csv' INTO TABLE csv_data;

Archive 引擎

-- 高压缩比存储
INSERT INTO archive_logs SELECT * FROM access_log;-- 只支持插入查询
SELECT * FROM archive_logs WHERE id=100;  -- 全表扫描

5. 生产环境选型

OLTP 系统

分析系统

6. 性能优化指南

InnoDB 优化

# 缓冲池优化
innodb_buffer_pool_instances=8  # 多实例减少锁争用
innodb_flush_method=O_DIRECT    # 直接IO减少双缓冲# IO优化
innodb_io_capacity=2000         # SSD配置
innodb_read_io_threads=8
innodb_write_io_threads=8

MyISAM 优化

# 键缓存
key_buffer_size=512M# 并发插入
concurrent_insert=2