MySQL InnoDB Engine--数据页存储和UPDATE操作 2

准备测试环境：

MySQL 5.7.28 社区版
CentOS release 6.10

MySQL Undo参数配置：
innodb_undo_tablespaces = 1
innodb_default_row_format = dynamic

准备测试数据：

## 创建测试表
CREATE TABLE `TB001` (
  `ID` VARCHAR(20) NOT NULL,
  `C1` VARCHAR(20) NOT NULL,
  `C2` VARCHAR(20) NOT NULL,
  PRIMARY KEY (`ID`),
  KEY `IDX_C1` (`C1`)
) ENGINE=INNODB DEFAULT CHARSET=utf8;

## 第一次插入数据
INSERT INTO `TB001`(ID,C1,C2)VALUES('AA0001','BB0001','CC0001'),('AA0002','BB0002','CC0002'),('AA0003','BB0003','CC0003');


## 查看数据
SELECT * FROM TB001;
+--------+--------+--------+
| ID     | C1     | C2     |
+--------+--------+--------+
| AA0001 | BB0001 | CC0001 |
| AA0002 | BB0002 | CC0002 |
| AA0003 | BB0003 | CC0003 |
+--------+--------+--------+

测试操作：

## 将C2列值长度从6扩展至8
UPDATE TB001 SET C2='CC000111' WHERE ID='AA0001';
## 将C2列值长度从6缩短至4
UPDATE TB001 SET C2='CC03' WHERE ID='AA0003';

更新前叶子节点数据：

06 06 06 00 00 10 00 27 41 41 30 30 30 31 00 00 00 00 05 78 D3 00 00 00 A6 01 10 42 42 30 30 30 31 43 43 30 30 30 31 
06 06 06 00 00 18 00 27 41 41 30 30 30 32 00 00 00 00 05 78 D3 00 00 00 A6 01 1E 42 42 30 30 30 32 43 43 30 30 30 32 
06 06 06 00 00 20 FF A2 41 41 30 30 30 33 00 00 00 00 05 78 D3 00 00 00 A6 01 2C 42 42 30 30 30 33 43 43 30 30 30 33

更新后叶子节点数据：

06 06 06 00 00 10 00 00 41 41 30 30 30 31 00 00 00 00 05 78 D3 00 00 00 A6 01 10 42 42 30 30 30 31 43 43 30 30 30 31 
06 06 06 00 00 18 00 27 41 41 30 30 30 32 00 00 00 00 05 78 D3 00 00 00 A6 01 1E 42 42 30 30 30 32 43 43 30 30 30 32 
04 06 06 00 00 20 FF A2 41 41 30 30 30 33 00 00 00 00 05 80 58 00 00 00 AA 01 10 42 42 30 30 30 33 43 43 30 33 30 33 
08 06 06 00 00 28 FF B2 41 41 30 30 30 31 00 00 00 00 05 7E 57 00 00 00 A9 01 10 42 42 30 30 30 31 43 43 30 30 30 31 31 31

前后数据对比：

未完待续