InnoDB备忘录 - B+Tree索引

栏目: 数据库 · 发布时间: 6年前

内容简介:InnoDB备忘录 - B+Tree索引

本文主要介绍 InnoDB 存储引擎的 B+Tree索引

B+Tree数据结构

InnoDB备忘录 - B+Tree索引

  1. 所有 叶子节点 出现在 同一层
  2. 叶子节点 包含 关键字信息
  3. 叶子节点 本身构成 单向有序链表
  4. 叶子节点 内部的记录也构成 单向有序链表
  5. 索引节点 不包含 关键字信息 ,能容纳更多的索引信息, 树高很低 ,查找效率很高

关于B+Tree的更多内容请查看 维基百科

MyISAM与InnoDB

MyISAM

  1. 索引文件数据文件 分离
  2. MyISAM 的索引文件采用 B+Tree 索引
  3. 叶子节点data域 记录的是 数据存放的地址
  4. 主索引(唯一)辅助索引(可重复) 在结构上 没有任何区别

InnoDB备忘录 - B+Tree索引

InnoDB

  1. 数据文件 本身是按照 B+Tree 组织的索引结构( 主索引聚集索引Primary IndexClustered Index ),而 叶子节点data域 记录的是 完整的数据信息
  2. InnoDB 必须有主键 ,如果没有 显式定义主键唯一非NULL索引 ,InnoDB会自动生成 6Byte的ROWID 作为主键
  3. 辅助索引Secondary Index )也是按 B+Tree 组织, 叶子节点data域 记录的是 主键值 ,因此 主键不宜定义太大
  4. 辅助索引 搜索需要 遍历两遍索引 ,首先通过辅助索引获得主键,再用主键值在主索引中获取实际数据

InnoDB备忘录 - B+Tree索引

单列主键下的DML操作

本节将通过实例介绍在 单列主键下的DML操作 时, B+Tree索引 是如何变化的,关于页内查找的实例请参照「InnoDB备忘录 - 数据页结构」

Insert

Leaf Page满

  1. 拆分 Leaf Page ,将 中间节点 放入到 Index Page
  2. 小于 中间节点的行记录放在 左边Leaf Page
  3. 大于 中间节点的行记录放 右边Leaf Page

表初始化

mysql> CREATE TABLE t (
    -> a INT NOT NULL PRIMARY KEY,
    -> b VARCHAR(3500)
    -> ) ENGINE=INNODB CHARSET=LATIN1 ROW_FORMAT=COMPACT;
Query OK, 0 rows affected (0.08 sec)

mysql> INSERT INTO t SELECT 10,REPEAT('a',3500);
Query OK, 1 row affected (0.02 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 20,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 30,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 40,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 6:
Freshly Allocated Page: 2
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 1
File Segment inode: 1
  1. CHARSET=LATIN1 ROW_FORMAT=COMPACT 下,每个行记录占用 3525 Byte (相关内容请参照「InnoDB备忘录 - 行记录格式」)
  2. ROW_FORMAT=COMPACT 下,每个页固定占用(不考虑 User RecordsFree SpacePage Directory ,相关内容请参照「InnoDB备忘录 - 数据页结构」) 128 Bytes
  3. 默认页大小为 16KB ,因此数据页最多容纳 (16*1024-128)/3525=4 个行记录(这里 Page Directory 可忽略不计)
  4. 插入 4 条记录后,只有一个 Leaf Page ,再插入第 5 条记录时, B+Tree 索引会 分裂

InnoDB备忘录 - B+Tree索引

Insert 50

mysql> INSERT INTO t SELECT 50,REPEAT('a',3500);
Query OK, 1 row affected (0.02 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
Total number of page: 6:
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 3
File Segment inode: 1
# page offset=3
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 000a 0000 0004 0000 0019 ffe4 8000 001e  ................
0000c090: 0000 0005 0000 0000 0000 0000 0000 0000  ................
  1. 插入第5条记录 a=50 后, 10 20 30 40 50 无法完全容纳在 page offset=3Leaf Page ,需要进行分裂
  2. 中间节点是 30 ,将 30 (包括最小值 10 )提取到 page Offset=3Index Page (保存的是 主键a与页偏移的映射
  3. 10 20 提取到 page offset=4Leaf Page (保存的是 行记录
  4. 30 40 50 提取到 page offset=5Leaf Page
    • 如果插入的是 25 ,分组为 10 20 2530 40
地址 值(16进制) 描述
0xc07e~0xc085 8000 000a 0000 0004 主键 a=10 的行记录在 page offset=4Leaf Page
0xc08c~0xc093 8000 001e 0000 0005 主键 a=30 的行记录在 page offset=5Leaf Page

InnoDB备忘录 - B+Tree索引

Leaf Page未满

接着上述步骤继续操作,直接将行记录 a=15 插入到 page offset=4Leaf Page

Insert 15

mysql> INSERT INTO t SELECT 15,REPEAT('a',3500);
Query OK, 1 row affected (0.06 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
Total number of page: 6:
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 3
File Segment inode: 1
# page offset=3
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 000a 0000 0004 0000 0019 ffe4 8000 001e  ................
0000c090: 0000 0005 0000 0000 0000 0000 0000 0000  ................
......
# page offset=4
# a=10
00010070: 7375 7072 656d 756d ac8d 0000 0010 1b8a  supremum........
00010080: 8000 000a 0000 0014 0b41 fc00 0001 f201  .........A......
00010090: 1061 6161 6161 6161 6161 6161 6161 6161  .aaaaaaaaaaaaaaa
......
# a=20
00010e30: 6161 6161 6161 6161 6161 6161 61ac 8d00  aaaaaaaaaaaaa...
00010e40: 0000 18f2 2b80 0000 1400 0000 140b 42fd  ....+.........B.
00010e50: 0000 01f3 0110 6161 6161 6161 6161 6161  ......aaaaaaaaaa
......
# a=15
00011c00: 6161 ac8d 0000 0020 f23b 8000 000f 0000  aa..... .;......
00011c10: 0014 0b4e a500 0001 fb01 1061 6161 6161  ...N.......aaaaa
地址 值(16进制) 描述
0xc07e~0xc085 8000 000a 0000 0004 主键 a=10 的行记录在 page offset=4Leaf Page
0xc08c~0xc093 8000 001e 0000 0005 主键 a=30 的行记录在 page offset=5Leaf Page
0x10080~0x10083 8000 000a 主键 a=10 的行记录的 ROWID 字段
0x10e45~0x10e48 8000 0014 主键 a=20 的行记录的 ROWID 字段
0x11c0a~0x11c0d 8000 000f 主键 a=15 的行记录的 ROWID 字段
  1. page offset=4 内可见,物理存储顺序为 10,20,15非物理有序 ,通过 Page Directorynext_record 保持 逻辑有序单向有序列表
  2. 行记录格式数据页结构 的内容请参照「InnoDB备忘录 - 行记录格式」和「InnoDB备忘录 - 数据页结构」

InnoDB备忘录 - B+Tree索引

Leaf Page中显示的是 逻辑顺序 10,15,20

Index Page满

  1. 拆分 Index Page ,中间节点放入上一次 Index Page
  2. 小于 中间节点的记录放 左边Index Page
  3. 大于 中间节点的记录放 右边Index Page

表初始化

mysql> CREATE TABLE t (
    -> a VARCHAR(750) NOT NULL PRIMARY KEY,
    -> b VARCHAR(6500)
    -> ) ENGINE=INNODB CHARSET=LATIN1 ROW_FORMAT=COMPACT;
Query OK, 0 rows affected (0.11 sec)

mysql> DELIMITER //                                                                                                                    mysql> CREATE PROCEDURE load_t (count INT UNSIGNED)
    -> BEGIN
    -> SET @c=0;
    -> WHILE @c < count DO
    -> SET @x=(@c DIV 10);
    -> SET @y=(@c MOD 10);
    -> INSERT INTO t SELECT REPEAT(CONCAT(CHAR(48+@x),CHAR(48+@y)),375) , REPEAT('z',6500);
    -> SET @c=@c+1;
    -> END WHILE;
    -> END;
    -> //
Query OK, 0 rows affected (0.00 sec)

mysql> CALL load_t(41);
Query OK, 0 rows affected (0.09 sec)
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
page offset 00000007, page type <B-tree Node>, page level <0000>
......
page offset 00000016, page type <B-tree Node>, page level <0000>
page offset 00000017, page type <B-tree Node>, page level <0000>
page offset 00000018, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 26:
Freshly Allocated Page: 1
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 22
File Segment inode: 1
# page offset=3
0000c360: 3030 3030 3030 3030 3030 3030 3030 0000  00000000000000..
0000c370: 0004 ee82 0000 0019 02fa 3031 3031 3031  ..........010101
......
0000c660: 3031 3031 3031 3031 0000 0005 ee82 0000  01010101........
0000c670: 0021 02fa 3033 3033 3033 3033 3033 3033  .!..030303030303
......
0000c950: 3033 3033 3033 3033 3033 3033 3033 3033  0303030303030303
0000c960: 3033 0000 0006 ee82 0004 0029 02fa 3035  03.........)..05
......
0000f8f0: 3335 3335 3335 3335 3335 3335 3335 3335  3535353535353535
0000f900: 3335 0000 0016 ee82 0000 00a9 02fa 3337  35............37
0000f910: 3337 3337 3337 3337 3337 3337 3337 3337  3737373737373737
......
0000fbf0: 3337 3337 3337 3337 3337 3337 0000 0017  373737373737....
0000fc00: ee82 0000 00b1 c468 3339 3339 3339 3339  .......h39393939
......
0000fef0: 3339 3339 3339 0000 0018 0000 0000 0000  393939..........

InnoDB备忘录 - B+Tree索引

  1. CHARSET=LATIN1 ROW_FORMAT=COMPACT 下, Leaf Page 每个行记录占用 7273 Bytes ,页大小为 16KB 时,最多存放 (16384-128)/7273=2 个行记录
  2. CHARSET=LATIN1 ROW_FORMAT=COMPACT 下, Index Page 每个行记录( 索引信息 )占用 762 Bytes ,页大小为 16KB 时,最多存放 (16384-128)/762=21 个行记录
    • Index Page 中的每一个行记录( 索引信息 )中会指向一个 Leaf Page ,每个 Leaf Page 最多包含 2 条行记录,理论上因此应该 CALL load_t(42)
    • 但是在已经插入了 00 01 ,准备插入 02 时,此时只有一个 Leaf Page ,没有 Index Page ,这会新建一个 Index Page ,导致 B+Tree增高00 会放入一个 Leaf Page01 02 放入另一个 Leaf Page ,因此只需要 CALL load_t(41) 就可以将 page offset=3Index Page 塞满,再插入记录就需要进行下一步 分裂 (B+Tree继续增高)

注:这里的 00 其实指的是 a=REPEAT('00',375) 的行记录

Insert 42th Reocrd

mysql> INSERT INTO t SELECT REPEAT(CONCAT(CHAR(48+4),CHAR(48+1)),375) , REPEAT('z',6500);
Query OK, 1 row affected (0.31 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0002>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
......
page offset 00000017, page type <B-tree Node>, page level <0000>
page offset 00000018, page type <B-tree Node>, page level <0000>
page offset 00000019, page type <B-tree Node>, page level <0000>
page offset 0000001a, page type <B-tree Node>, page level <0001>
page offset 0000001b, page type <B-tree Node>, page level <0001>
Total number of page: 28:
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 25
File Segment inode: 1
# page offset=3
0000c360: 3030 3030 3030 3030 3030 3030 3030 0000  00000000000000..
0000c370: 001a ee82 0000 0019 fcf6 3139 3139 3139  ..........191919
......
0000c660: 3139 3139 3139 3139 0000 001b 0000 0000  19191919........

# page offset=0x1a
00068030: 0000 0005 0000 000a 0000 0000 0000 0000  ................
......
00068360: 3030 3030 3030 3030 3030 3030 3030 0000  00000000000000..
00068370: 0004 ee82 0000 0019 02fa 3031 3031 3031  ..........010101
......
00068660: 3031 3031 3031 3031 0000 0005 ee82 0000  01010101........
00068670: 0021 02fa 3033 3033 3033 3033 3033 3033  .!..030303030303
......
00069b30: 3135 3135 3135 3135 3135 3135 3135 0000  15151515151515..
00069b40: 000c ee82 0000 0059 e526 3137 3137 3137  .......Y.&171717
......
00069e30: 3137 3137 3137 3137 0000 000d ee82 0000  17171717........
00069e40: 0061 02fa 3139 3139 3139 3139 3139 3139  .a..191919191919
......
0006bef0: 3339 3339 3339 0000 0018 0000 0000 0000  393939..........

# page offset=0x1b
0006c360: 3139 3139 3139 3139 3139 3139 3139 0000  19191919191919..
0006c370: 000e ee82 0000 0019 02fa 3231 3231 3231  ..........212121
......
0006c660: 3231 3231 3231 3231 0000 000f ee82 0000  21212121........
0006c670: 0021 02fa 3233 3233 3233 3233 3233 3233  .!..232323232323
......
0006e130: 3339 0000 0018 ee82 0000 0069 df32 3431  39.........i.241
......
0006e420: 3431 3431 3431 3431 3431 3431 0000 0019  414141414141....

InnoDB备忘录 - B+Tree索引

  1. CALL load_t(41) 后, page offset=3Index Page 已经塞满, page offset=18Leaf Page 也已经塞满,因此在插入第42条行记录是,会新建 Leaf Page ,并且尝试将 索引信息 放入 page offset=3Index Page
  2. page offset=3Index Page 这时需要 分裂 ,将其中的中间节点 19 (包括最小节点 00 )提取到上一层的 Index Page
    • 00 ~ 17 的节点放入 page offset=1aIndex Page 中(其中包括了冗余节点 19 ~ 39 ,后续再插入数据会被重用这部分空间)
    • 19 ~ 39 的节点放入 page offset=1bIndex Page 中(新建的索引信息 41 也在这个页中)

Delete

表初始化

mysql> CREATE TABLE t (
    -> a INT NOT NULL PRIMARY KEY,
    -> b VARCHAR(3500)
    -> ) ENGINE=INNODB CHARSET=LATIN1 ROW_FORMAT=COMPACT;
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO t SELECT 0x10,REPEAT('a',3500);                                                                                     Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x20,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x30,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x40,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x50,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x60,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x70,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x80,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 8:
Freshly Allocated Page: 1
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 4
File Segment inode: 1
0000c060: 0200 1b69 6e66 696d 756d 0004 000b 0000  ...infimum......
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 0010 0000 0004 0000 0019 000e 8000 0030  ...............0
0000c090: 0000 0005 0000 0021 ffd6 8000 0070 0000  .......!.....p..
0000c0a0: 0006 0000 0000 0000 0000 0000 0000 0000  ................
主键a 页偏移 说明
80 00 00 10 00 00 00 04 包含行记录:0x10、0x20
80 00 00 30 00 00 00 05 包含行记录:0x30、0x40、0x50、0x60
80 00 00 70 00 00 00 06 包含行记录:0x70、0x80

InnoDB备忘录 - B+Tree索引

Delete 0x10

mysql> DELETE FROM t WHERE a=0x10;
Query OK, 1 row affected (0.03 sec)
# page offset=3
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 8:
Freshly Allocated Page: 1
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 4
File Segment inode: 1
# page offset=3
0000c060: 0200 1b69 6e66 696d 756d 0004 000b 0000  ...infimum......
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 0010 0000 0004 0000 0019 000e 8000 0030  ...............0
0000c090: 0000 0005 0000 0021 ffd6 8000 0070 0000  .......!.....p..
0000c0a0: 0006 0000 0000 0000 0000 0000 0000 0000  ................

# page offset=4
00010070: 7375 7072 656d 756d ac8d 0020 0010 0dc5  supremum... ....
00010080: 8000 0010 0000 0014 287c 7700 0001 d919  ........(|w.....
00010090: 1061 6161 6161 6161 6161 6161 6161 6161  .aaaaaaaaaaaaaaa
主键a 页偏移 说明
80 00 00 10 00 00 00 04 包含行记录:0x10( deleted_flag=1 )、0x20
80 00 00 30 00 00 00 05 包含行记录:0x30、0x40、0x50、0x60
80 00 00 70 00 00 00 06 包含行记录:0x70、0x80
  1. DELETE 操作仅仅是将记录 标记为删除deleted_flag=1 ),实际的删除操作是在 Purge线程 中完成的
  2. Index Page 最小的行记录依旧是 0x10 (查找所有主键小于 0x30 的行记录都将 page offset=4Leaf Page 载入内存)

InnoDB备忘录 - B+Tree索引

Insert 0x10

mysql> INSERT INTO t SELECT 0x10,REPEAT('a',3500);
Query OK, 1 row affected (0.14 sec)
Records: 1  Duplicates: 0  Warnings: 0
# page offset=3
0000c060: 0200 1b69 6e66 696d 756d 0004 000b 0000  ...infimum......
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 0010 0000 0004 0000 0019 000e 8000 0030  ...............0
0000c090: 0000 0005 0000 0021 ffd6 8000 0070 0000  .......!.....p..
0000c0a0: 0006 0000 0000 0000 0000 0000 0000 0000  ................

# page offset=4
00010070: 7375 7072 656d 756d ac8d 0000 0010 0dc5  supremum........
00010080: 8000 0010 0000 0014 2891 a200 0001 f801  ........(.......
00010090: 1062 6262 6262 6262 6262 6262 6262 6262  .bbbbbbbbbbbbbbb
主键a 页偏移 说明
80 00 00 10 00 00 00 04 包含行记录:0x10、0x20
80 00 00 30 00 00 00 05 包含行记录:0x30、0x40、0x50、0x60
80 00 00 70 00 00 00 06 包含行记录:0x70、0x80
  1. Purge线程 未回收标记已删除的空间时,再次插入 0x10 ,将 重用 该空间
  2. Index Page 最小的行记录依旧是 0x10 (查找所有主键小于 0x30 的行记录都将 page offset=4Leaf Page 载入内存)

InnoDB备忘录 - B+Tree索引

Delete 0x10 + Insert 0x08

mysql> DELETE FROM t WHERE a=0x10;
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO t SELECT 0x08,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 9:
Freshly Allocated Page: 2
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 4
File Segment inode: 1
# page offset=3
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 0010 0000 0004 0000 0019 000e 8000 0030  ...............0
0000c090: 0000 0005 0000 0021 ffd6 8000 0070 0000  .......!.....p..
0000c0a0: 0006 0000 0000 0000 0000 0000 0000 0000  ................

# page offset=4
00010070: 7375 7072 656d 756d ac8d 0000 0010 0dc5  supremum........
00010080: 8000 0008 0000 0014 2898 a600 0001 fc01  ........(.......
00010090: 1061 6161 6161 6161 6161 6161 6161 6161  .aaaaaaaaaaaaaaa
主键a 页偏移 说明
80 00 00 10 00 00 00 04 包含行记录: 0x08 、0x20
80 00 00 30 00 00 00 05 包含行记录:0x30、0x40、0x50、0x60
80 00 00 70 00 00 00 06 包含行记录:0x70、0x80

InnoDB备忘录 - B+Tree索引

  1. 0x08 重用标记为已删除的 0x10 的空间
  2. Index Page 最小的行记录依旧是 0x10 (查找所有主键小于 0x30 的行记录都将 page offset=4Leaf Page 载入内存)

Insert 0x68

mysql> INSERT INTO t SELECT 0x68,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 9:
Freshly Allocated Page: 2
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 4
File Segment inode: 1
# page offset=3
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 0010 0000 0004 0000 0019 000e 8000 0030  ...............0
0000c090: 0000 0005 0000 0021 ffd6 8000 0068 0000  .......!.....h..
0000c0a0: 0006 0000 0000 0000 0000 0000 0000 0000  ................

# page offset=6
00018070: 7375 7072 656d 756d ac8d 0000 0010 0dc5  supremum........
00018080: 8000 0070 0000 0014 289f aa00 0001 9601  ...p....(.......
00018090: 1061 6161 6161 6161 6161 6161 6161 6161  .aaaaaaaaaaaaaaa
......
00018e30: 6161 6161 6161 6161 6161 6161 61ac 8d00  aaaaaaaaaaaaa...
00018e40: 0000 18f2 2b80 0000 8000 0000 1428 7bf6  ....+........({.
00018e50: 0000 01ca 0110 6161 6161 6161 6161 6161  ......aaaaaaaaaa
......
00019c00: 6161 ac8d 0000 0020 e476 8000 0068 0000  aa..... .v...h..
00019c10: 0014 28a0 ab00 0001 ff01 1061 6161 6161  ..(........aaaaa
主键a 页偏移 说明
80 00 00 10 00 00 00 04 包含行记录: 0x08 、0x20
80 00 00 30 00 00 00 05 包含行记录:0x30、0x40、0x50、0x60
80 00 00 68 00 00 00 06 包含行记录: 0x68 、0x70、0x80

InnoDB备忘录 - B+Tree索引

  1. Leaf Page 的行记录是 物理无序逻辑有序 (通过 next_reocord 保证)
  2. Index Page 最大的行记录从 0x70 修改了 0x68 ,因为如果不修改,当查找 0x68 这条行记录时,将 page offset=5Leaf Page 载入内存,而 0x68 实际上是在 page offset=6Leaf Page

Delete 0x30,0x40,0x50,0x60

mysql> DELETE FROM t WHERE a IN (0x30,0x40,0x50,0x60);
Query OK, 4 rows affected (0.03 sec)
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 9:
Freshly Allocated Page: 2
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 4
File Segment inode: 1
# page offset=3
0000c070: 7375 7072 656d 756d 0010 0011 001c 8000  supremum........
0000c080: 0010 0000 0004 0000 0019 0000 8000 0030  ...............0
0000c090: 0000 0005 0000 0021 ffd6 8000 0068 0000  .......!.....h..
0000c0a0: 0006 0000 0000 0000 0000 0000 0000 0000  ................

# page offset=4
00010000: 6e19 4026 0000 0004 ffff ffff 0000 0006  n.@&............

# page offset=5
00014070: 7375 7072 656d 756d ac8d 0020 0010 294f  supremum... ..)O
00014080: 8000 0030 0000 0014 28a5 2e00 0002 060a  ...0....(.......
......
00014e30: 6161 6161 6161 6161 6161 6161 61ac 8d00  aaaaaaaaaaaaa...
00014e40: 2000 180d c580 0000 4000 0000 1428 a52e   .......@....(..
00014e50: 0000 0206 0a8e 6161 6161 6161 6161 6161  ......aaaaaaaaaa
......
00015c00: 6161 ac8d 0020 0020 0000 8000 0050 0000  aa... . .....P..
00015c10: 0014 28a5 2e00 0002 060a b161 6161 6161  ..(........aaaaa
......
000169c0: 6161 6161 6161 61ac 8d00 2000 28d6 a180  aaaaaaa... .(...
000169d0: 0000 6000 0000 1428 a52e 0000 0206 0ad4  ..`....(........
主键a 页偏移 说明
80 00 00 10 00 00 00 04 包含行记录: 0x08 、0x20
80 00 00 68 00 00 00 06 包含行记录: 0x68 、0x70、0x80

InnoDB备忘录 - B+Tree索引

  1. page offset=5Leaf Page 中的行记录0x30、0x40、0x50、0x60 标记为已删除
  2. page offset=4Leaf Page 中的 FIL_PAGE_NEXT5 变成了 60x1000c~1000f
  3. Index Page 中行记录的 单向链表 也由 0x10->0x30->0x68 变成了 0x10->0x68

Insert 0x48

mysql> INSERT INTO t SELECT 0x48,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 9:
Freshly Allocated Page: 2
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 4
File Segment inode: 1
# page offset=3
0000c070: 7375 7072 656d 756d 0010 0011 001c 8000  supremum........
0000c080: 0010 0000 0004 0000 0019 0000 8000 0030  ...............0
0000c090: 0000 0005 0000 0021 ffd6 8000 0068 0000  .......!.....h..
0000c0a0: 0006 0000 0000 0000 0000 0000 0000 0000  ................

# page offset=4
00011c00: 6161 ac8d 0000 0020 e466 8000 0048 0000  aa..... .f...H..
00011c10: 0014 28b6 b700 0001 9401 1061 6161 6161  ..(........aaaaa
主键a 页偏移 说明
80 00 00 10 00 00 00 04 包含行记录: 0x08 、0x20、 0x48
80 00 00 68 00 00 00 06 包含行记录: 0x68 、0x70、0x80

InnoDB备忘录 - B+Tree索引

Update

表初始化

mysql> CREATE TABLE t (
    -> a INT NOT NULL PRIMARY KEY,
    -> b VARCHAR(3500)
    -> ) ENGINE=INNODB CHARSET=LATIN1 ROW_FORMAT=COMPACT;
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO t SELECT 0x10,REPEAT('a',3500);                                                                                     Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x20,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x30,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x40,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x50,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x60,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x70,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x80,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

InnoDB备忘录 - B+Tree索引

更新主键列

mysql> UPDATE t SET a=0x68 WHERE a=0x70;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 9:
Freshly Allocated Page: 2
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 4
File Segment inode: 1
# page offset=3
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 0010 0000 0004 0000 0019 000e 8000 0030  ...............0
0000c090: 0000 0005 0000 0021 ffd6 8000 0068 0000  .......!.....h..
0000c0a0: 0006 0000 0000 0000 0000 0000 0000 0000  ................

# page offset=6
00018070: 7375 7072 656d 756d ac8d 0020 0010 0dc5  supremum... ....
00018080: 8000 0070 0000 0014 28e6 3800 0002 3003  ...p....(.8...0.
00018090: f761 6161 6161 6161 6161 6161 6161 6161  .aaaaaaaaaaaaaaa
......
00018e30: 6161 6161 6161 6161 6161 6161 61ac 8d00  aaaaaaaaaaaaa...
00018e40: 0000 18f2 2b80 0000 8000 0000 1428 e1b5  ....+........(..
00018e50: 0000 0191 0110 6161 6161 6161 6161 6161  ......aaaaaaaaaa
......
00019c00: 6161 ac8d 0000 0020 e476 8000 0068 0000  aa..... .v...h..
00019c10: 0014 28e6 b800 0001 9701 1061 6161 6161  ..(........aaaaa
00019c20: 6161 6161 6161 6161 6161 6161 6161 6161  aaaaaaaaaaaaaaaa
主键a 页偏移 说明
80 00 00 10 00 00 00 04 包含行记录:0x10,0x20
80 00 00 30 00 00 00 05 包含行记录:0x30、0x40、0x50、0x60
80 00 00 68 00 00 00 06 包含行记录:0x68、0x70( deleted_flag=1 )、0x80

InnoDB备忘录 - B+Tree索引

  1. 更新主键 a:0x70->0x68 ,首先是逻辑删除 0x70MVCC 特性),然后再插入 0x68
  2. 如果插入的过程中会影响查询过程,会同步更新 Index Page

更新非主键列

mysql> UPDATE t SET b=REPEAT('b',100) WHERE a=0x68;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
page offset 00000000, page type <Freshly Allocated Page>
page offset 00000000, page type <Freshly Allocated Page>
Total number of page: 9:
Freshly Allocated Page: 2
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 4
File Segment inode: 1
# page offset=3
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 0010 0000 0004 0000 0019 000e 8000 0030  ...............0
0000c090: 0000 0005 0000 0021 ffd6 8000 0068 0000  .......!.....h..
0000c0a0: 0006 0000 0000 0000 0000 0000 0000 0000  ................

# page offset=6
00019c00: 6161 6400 0000 20f2 3c80 0000 6800 0000  aad... .<...h...
00019c10: 1428 e839 0000 0220 14fe 6262 6262 6262  .(.9... ..bbbbbb
00019c20: 6262 6262 6262 6262 6262 6262 6262 6262  bbbbbbbbbbbbbbbb
00019c30: 6262 6262 6262 6262 6262 6262 6262 6262  bbbbbbbbbbbbbbbb
00019c40: 6262 6262 6262 6262 6262 6262 6262 6262  bbbbbbbbbbbbbbbb
00019c50: 6262 6262 6262 6262 6262 6262 6262 6262  bbbbbbbbbbbbbbbb
00019c60: 6262 6262 6262 6262 6262 6262 6262 6262  bbbbbbbbbbbbbbbb
00019c70: 6262 6262 6262 6262 6262 6262 6262 6161  bbbbbbbbbbbbbbaa
00019c80: 6161 6161 6161 6161 6161 6161 6161 6161  aaaaaaaaaaaaaaaa

更新非主键列时 无需逻辑删除直接更新 相应行记录

聚集索引与辅助索引

mysql> CREATE TABLE t (
    -> a INT NOT NULL,
    -> b INT NOT NULL,
    -> c VARCHAR(3500),
    -> PRIMARY KEY (a),
    -> KEY (b)
    -> ) ENGINE=INNODB CHARSET=LATIN1 ROW_FORMAT=COMPACT;
Query OK, 0 rows affected (0.13 sec)

mysql> SHOW INDEX FROM t;
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| t     |          0 | PRIMARY  |            1 | a           | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| t     |          1 | b        |            1 | b           | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
2 rows in set (0.00 sec)

mysql> INSERT INTO t SELECT 0x10,0x100,REPEAT('a',3500);
Query OK, 1 row affected (0.04 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x20,0x200,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x30,0x300,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x40,0x400,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 0x50,0x500,REPEAT('a',3500);
Query OK, 1 row affected (0.02 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
page offset 00000006, page type <B-tree Node>, page level <0000>
Total number of page: 7:
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 4
File Segment inode: 1
# page offset=3
0000c060: 0200 1b69 6e66 696d 756d 0003 000b 0000  ...infimum......
0000c070: 7375 7072 656d 756d 0010 0011 000e 8000  supremum........
0000c080: 0010 0000 0005 0000 0019 ffe4 8000 0030  ...............0
0000c090: 0000 0006 0000 0000 0000 0000 0000 0000  ................

# page offset=4
00010070: 7375 7072 656d 756d 0000 1000 0d80 0001  supremum........
00010080: 0080 0000 1000 0018 000d 8000 0200 8000  ................
00010090: 0020 0000 2000 0d80 0003 0080 0000 3000  . .. .........0.
000100a0: 0028 000d 8000 0400 8000 0040 0000 30ff  .(.........@..0.
000100b0: bf80 0005 0080 0000 5000 0000 0000 0000  ........P.......

# page offset=5
00014070: 7375 7072 656d 756d ac8d 0000 0010 0dc9  supremum........
00014080: 8000 0010 0000 0014 2917 da00 0001 ac01  ........).......
00014090: 1080 0001 0061 6161 6161 6161 6161 6161  .....aaaaaaaaaaa
......
00014e40: 61ac 8d00 0000 18f2 2780 0000 2000 0000  a.......'... ...
00014e50: 1429 18db 0000 01ad 0110 8000 0200 6161  .)............aa
00014e60: 6161 6161 6161 6161 6161 6161 6161 6161  aaaaaaaaaaaaaaaa

# page offset=6
00018070: 7375 7072 656d 756d ac8d 0000 0010 0dc9  supremum........
00018080: 8000 0030 0000 0014 291d de00 0001 b301  ...0....).......
00018090: 1080 0003 0061 6161 6161 6161 6161 6161  .....aaaaaaaaaaa
......
00018e40: 61ac 8d00 0000 180d c980 0000 4000 0000  a...........@...
00018e50: 1429 1edf 0000 01b7 0110 8000 0400 6161  .)............aa
......
00019c00: 6161 6161 6161 6161 6161 ac8d 0000 0020  aaaaaaaaaa.....
00019c10: e45e 8000 0050 0000 0014 2923 e200 0001  .^...P....)#....
00019c20: c501 1080 0005 0061 6161 6161 6161 6161  .......aaaaaaaaa

聚集索引的 Index Page (目前只有一个Page)在 page offset=3

地址 16进制 描述
0xc07e~0xc085 8000 0010 0000 0005 a=0x10 的行记录在 page offset=5Leaf Page
0xc08c~0xc093 8000 0030 0000 0006 a=0x30 的行记录在 page offset=6Leaf Page

辅助索引的 Index Page (目前只有一个Page)在 page offset=4

地址 16进制 描述
0x1007d~0x10084 8000 0100 8000 0010 b=0x100 对应 a=0x10
0x1008a~0x10091 8000 0100 8000 0010 b=0x200 对应 a=0x20
0x10097~0x1009e 8000 0100 8000 0010 b=0x300 对应 a=0x30
0x100a4~0x100ab 8000 0100 8000 0010 b=0x400 对应 a=0x40
0x100b1~0x100b8 8000 0100 8000 0010 b=0x500 对应 a=0x50

InnoDB备忘录 - B+Tree索引

联合索引

当表中有 联合索引(a,b) ,能有效利用联合索引的查询(因为索引已经按a,b的顺序进行 排序 的)

  1. WHERE a=xxx AND b=xxx
  2. WHERE a=xxx
  3. WHERE a=xxx ORDER BY b

不能有效利用联合索引的查询: WHERE a=xxx ,因为没有一个索引 (b)(b,a)

mysql> CREATE TABLE t (
    -> a INT NOT NULL,
    -> b INT NOT NULL,
    -> c VARCHAR(3500),
    -> PRIMARY KEY (a,b)
    -> ) ENGINE=INNODB CHARSET=LATIN1 ROW_FORMAT=COMPACT;
Query OK, 0 rows affected (0.03 sec)

mysql> INSERT INTO t SELECT 1,1,REPEAT('a',3500);
Query OK, 1 row affected (0.05 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 2,1,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 2,2,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 2,3,REPEAT('a',3500);
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t SELECT 3,1,REPEAT('a',3500);
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0
$ sudo python py_innodb_page_info.py -v /var/lib/mysql/test/t.ibd
page offset 00000000, page type <File Space Header>
page offset 00000001, page type <Insert Buffer Bitmap>
page offset 00000002, page type <File Segment inode>
page offset 00000003, page type <B-tree Node>, page level <0001>
page offset 00000004, page type <B-tree Node>, page level <0000>
page offset 00000005, page type <B-tree Node>, page level <0000>
Total number of page: 6:
Insert Buffer Bitmap: 1
File Space Header: 1
B-tree Node: 3
File Segment inode: 1
# page offset=3
0000c070: 7375 7072 656d 756d 0010 0011 0012 8000  supremum........
0000c080: 0001 8000 0001 0000 0004 0000 0019 ffe0  ................
0000c090: 8000 0002 8000 0002 0000 0005 0000 0000  ................
地址 16进制 描述
0xc07e~0xc089 8000 0001 8000 0001 0000 0004 a=1,b=1 的行记录在 page offset=4Leaf Page
0xc090~0xc09b 8000 0002 8000 0002 0000 0005 a=2,b=2 的行记录在 page offset=5Leaf Page

InnoDB备忘录 - B+Tree索引


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Base64 编码/解码
Base64 编码/解码

Base64 编码/解码

RGB CMYK 转换工具
RGB CMYK 转换工具

RGB CMYK 互转工具

HSV CMYK 转换工具
HSV CMYK 转换工具

HSV CMYK互换工具