sync-diff-inspector 比对表结构，索引
作者：TiDB 社区干货传送门
- 2024-08-16 北京
本文字数：10877 字
阅读完需：约 36 分钟
作者： Brian 原文来源：https://tidb.net/blog/f36c3f38
目的
以下对列默认值，列是否可为空，表的主键，表的唯一约束 不同的情况进行上右下表结构的比对
环境
上游环境：Mysql v5.7.37
下游环境：TiDB v6.5.6
tool 版本：sync-diff-inspector v6.5.7
Sync-diff-inspector 配置文件：
[tidb@vmxx.xx.xx-25 ~]$ cat sync-diff.yaml check-thread-count = 2export-fix-sql = truecheck-struct-only = false
[data-sources][data-sources.upstream] host = "xx.xx.xx.25" # 替换为实际上游集群 ip port = 3307 user = "root" password = "123" #snapshot = "448552618951966723" # 配置为实际的备份时间点[data-sources.downstream] host = "xx.xx.xx.25" # 替换为实际下游集群 ip port = 4000 user = "root" password = "123" #snapshot = "448553665253343269" # 配置为实际的恢复时间点
[task] output-dir = "./output" source-instances = ["upstream"] target-instance = "downstream" target-check-tables = ["t.t"]
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对比默认值
上游表结构：
root@localhost : t 06:55:43>>> show create table t;+-------+---------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+---------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |+-------+---------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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下游表结构：
mysql> show create table t;+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT '404', PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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对比结果：
上下游列默认值不同，可以校验通过。
[tidb@vmxx.xx.xx-25 ~]$ tidb-community-toolkit-v6.5.7-linux-amd64/sync_diff_inspector --config=sync-diff.yaml A total of 1 tables need to be compared
Comparing the table structure of ``t`.`t`` ... equivalentComparing the table data of ``t`.`t`` ... equivalent_____________________________________________________________________________Progress [============================================================>] 100% 0/0A total of 1 table have been compared and all are equal.You can view the comparision details through './output/sync_diff.log'
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对比列是否可为空
上游表结构：
root@localhost : t 06:55:43>>> show create table t;+-------+---------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+---------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |+-------+---------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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下游表结构：
mysql> show create table t;+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) NOT NULL, PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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对比结果：
上下游列是否可为空不同，可以校验通过。
[tidb@vmxx.xx.xx-25 ~]$ tidb-community-toolkit-v6.5.7-linux-amd64/sync_diff_inspector --config=sync-diff.yaml A total of 1 tables need to be compared
Comparing the table structure of ``t`.`t`` ... equivalentComparing the table data of ``t`.`t`` ... equivalent_____________________________________________________________________________Progress [============================================================>] 100% 0/0A total of 1 table have been compared and all are equal.You can view the comparision details through './output/sync_diff.log'
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对比表的主键
上游表结构：
root@localhost : t 07:15:15>>> show create table t;+-------+-----------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+-----------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |+-------+-----------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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下游表结构：
mysql> show create table t;+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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对比结果：
上下游中是否有主键不会校验，可以校验通过。
[tidb@vmxx.xx.xx-25 ~]$ tidb-community-toolkit-v6.5.7-linux-amd64/sync_diff_inspector --config=sync-diff.yaml A total of 1 tables need to be compared
Comparing the table structure of ``t`.`t`` ... equivalentComparing the table data of ``t`.`t`` ... equivalent_____________________________________________________________________________Progress [============================================================>] 100% 0/0A total of 1 table have been compared and all are equal.You can view the comparision details through './output/sync_diff.log'
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对比唯一索引和普通索引
上游表结构：
root@localhost : t 07:31:26>>> show create table t;+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`), KEY `name` (`name`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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下游表结构：
mysql> show create table t;+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */, UNIQUE KEY `name` (`name`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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对比结果：
对比唯一索引和普通索引，可以校验通过。
[tidb@vmxx.xx.xx-25 ~]$ tidb-community-toolkit-v6.5.7-linux-amd64/sync_diff_inspector --config=sync-diff.yaml A total of 1 tables need to be compared
Comparing the table structure of ``t`.`t`` ... equivalentComparing the table data of ``t`.`t`` ... equivalent_____________________________________________________________________________Progress [============================================================>] 100% 0/0A total of 1 table have been compared and all are equal.You can view the comparision details through './output/sync_diff.log'
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对比索引数量不同
上游表结构：
root@localhost : t 07:37:12>>> show create table t;+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, `addr` varchar(10) DEFAULT NULL, PRIMARY KEY (`id`), UNIQUE KEY `name` (`name`), KEY `addr` (`addr`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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下游表结构：
mysql> show create table t;+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, `addr` varchar(10) DEFAULT NULL, PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */, UNIQUE KEY `name` (`name`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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对比结果：
可以校验出来上下游表中的索引数量不同
[tidb@vmxx.xx.xx-25 ~]$ tidb-community-toolkit-v6.5.7-linux-amd64/sync_diff_inspector --config=sync-diff.yaml A total of 1 tables need to be compared
Comparing the table structure of ``t`.`t`` ... failureComparing the table data of ``t`.`t`` ... equivalent_____________________________________________________________________________Progress [============================================================>] 100% 0/0The structure of `t`.`t` is not equal
The rest of tables are all equal.
A total of 1 tables have been compared, 0 tables finished, 1 tables failed, 0 tables skipped.The patch file has been generated in 'output/fix-on-downstream/'You can view the comparision details through './output/sync_diff.log'
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对比单列索引覆盖列不同
上游表结构：
root@localhost : t 07:46:43>>> show create table t;+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, `addr` varchar(10) DEFAULT NULL, PRIMARY KEY (`id`), KEY `addr` (`addr`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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下游表结构：
mysql> show create table t;+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, `addr` varchar(10) DEFAULT NULL, PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */, KEY `name` (`name`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.01 sec)
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对比结果：
可以校验出来单列索引覆盖列不同
[tidb@vmxx.xx.xx-25 ~]$ tidb-community-toolkit-v6.5.7-linux-amd64/sync_diff_inspector --config=sync-diff.yaml A total of 1 tables need to be compared
Comparing the table structure of ``t`.`t`` ... failureComparing the table data of ``t`.`t`` ... equivalent_____________________________________________________________________________Progress [============================================================>] 100% 0/0The structure of `t`.`t` is not equal
The rest of tables are all equal.
A total of 1 tables have been compared, 0 tables finished, 1 tables failed, 0 tables skipped.The patch file has been generated in 'output/fix-on-downstream/'You can view the comparision details through './output/sync_diff.log'
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对比联合索引和单列索引
上游表结构：
root@localhost : t 07:46:46>>> show create table t;+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, `addr` varchar(10) DEFAULT NULL, PRIMARY KEY (`id`), KEY `addr` (`addr`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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下游表结构：
mysql> show create table t;+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+| t | CREATE TABLE `t` ( `id` int(11) NOT NULL, `name` varchar(20) DEFAULT NULL, `addr` varchar(10) DEFAULT NULL, PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */, KEY `name` (`name`,`addr`)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)
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对比结果：
可以校验出联合索引和单列索引的差异
[tidb@vmxx.xx.xx-25 ~]$ tidb-community-toolkit-v6.5.7-linux-amd64/sync_diff_inspector --config=sync-diff.yaml A total of 1 tables need to be compared
Comparing the table structure of ``t`.`t`` ... failureComparing the table data of ``t`.`t`` ... equivalent_____________________________________________________________________________Progress [============================================================>] 100% 0/0The structure of `t`.`t` is not equal
The rest of tables are all equal.
A total of 1 tables have been compared, 0 tables finished, 1 tables failed, 0 tables skipped.The patch file has been generated in 'output/fix-on-downstream/'You can view the comparision details through './output/sync_diff.log'
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结论
对于 sync-diff-inspector 校验表结构，有以下结论：
忽略校验：
列的默认值差异
列是否可以为空的差异
表是否有主键的差异
表中唯一索引和普通索引的差异
可校验：
索引（唯一索引 + 普通索引）数量的差异
单列索引覆盖列的差异
联合索引和单列索引的差异（即使联合索引和单列索引有相同的部分覆盖列）
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版权声明: 本文为 InfoQ 作者【TiDB 社区干货传送门】的原创文章。
原文链接:【http://xie.infoq.cn/article/b1854c111350a2a869d411bd6】。文章转载请联系作者。
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