Percona-Toolkit系列(29) --- pt-table-checksum

pt-table-checksum

pt-table-checksum:官方地址

说明

用途:验证MySQL主从复制的表数据是否一致。

语法:

pt-table-checksum [OPTIONS] [DSN]

通过在主从服务器上执行checksum查询,来对比checksump。如果不一致,则EXIT STATUS的值为非0。如果检测到表的数据不一致,可以通过pt-table-sync工具来同步表数据。

相比于老本的pt-table-checksum(1.0版本的Toolkit),新版本的pt-table-checksum更加简单,没有复杂的校验。更专注于单个数据库,单个表(也就是一次检查一张表)。它一次只能运行一个表,因此在开始校验和之前,它不会累积大量内存或执行大量工作。这使它可以在非常大的服务器上使用。我们在拥有数十万个数据库和表以及数万亿行的服务器上使用它。无论服务器有多大,pt-table-checksum同样运行良好。

pt-table-checksum会自动检测是否有从库,如果有则会自动连接上去。

支持Percona XtraDB Cluster (PXC) 5.5.28-23.7及更新版本。

限制:

  • 在主从环境中,pt-table-checksum要求必须使用基于STATEMENTbinlog复制,即binlog_format=STATEMENT
  • schema和表结构在主从上必须一致,如果不一致复制将会断开。

EXIT STATUS

不同的值代表不同的意思,如下:

FLAG              BIT VALUE  MEANING
================  =========  ==========================================
ERROR                     1  A non-fatal error occurred
ALREADY_RUNNING           2  --pid file exists and the PID is running
CAUGHT_SIGNAL             4  Caught SIGHUP, SIGINT, SIGPIPE, or SIGTERM
NO_SLAVES_FOUND           8  No replicas or cluster nodes were found
TABLE_DIFF               16  At least one diff was found
SKIP_CHUNK               32  At least one chunk was skipped
SKIP_TABLE               64  At least one table was skipped

pt-table-checksum执行

具体例子

检查单节点

检查monitor数据库下的所有表,当然意义不大。

[root@BigData ~]# pt-table-checksum h=192.168.20.5,u=root,p=Sanshi_408,P=3306 --databases=monitor
Checking if all tables can be checksummed ...
Starting checksum ...
Diffs cannot be detected because no slaves were found.  Please read the --recursion-method documentation for information.   ---提示没有检测到从库,这样的检查没啥意义。
            TS ERRORS  DIFFS     ROWS  DIFF_ROWS  CHUNKS SKIPPED    TIME TABLE
08-01T14:01:10      0      0        8          0       1       0   0.042 monitor.B_HOST
08-01T14:01:10      0      0       23          0       1       0   0.071 monitor.B_MONITOR_ITEM
08-01T14:01:11      0      0        7          0       1       0   0.111 monitor.B_SEND_MAIL
08-01T14:01:11      0      0        1          0       1       0   0.088 monitor.B_SEND_MAIL_FREQ
08-01T14:01:11      0      0        7          0       1       0   0.083 monitor.B_TRIGGER_RULE
08-01T14:01:11      0      0       14          0       1       0   0.100 monitor.B_WARN_CONFIG
08-01T14:01:11      0      0       46          0       1       0   0.095 monitor.B_WARN_INFO
08-01T14:01:11      0      0       14          0       1       0   0.066 monitor.B_WARN_ITEM
08-01T14:01:11      0      0        3          0       1       0   0.034 monitor.B_WARN_LEVEL
08-01T14:01:11      0      0        1          0       1       0   0.028 monitor.B_WARN_NOTICE
08-01T14:01:11      0      0        0          0       1       0   0.034 monitor.DATA_GROUP
08-01T14:01:11      0      0        0          0       1       0   0.029 monitor.DATA_GROUP_HOST
08-01T14:01:11      0      0        8          0       1       0   0.036 monitor.DB_GROUP
08-01T14:01:11      0      0       17          0       1       0   0.050 monitor.DB_VERSIONS
08-01T14:01:12      0      0        0          0       1       0   0.062 monitor.FLASH_INFO
08-01T14:01:12      0      0        0          0       1       0   0.042 monitor.FLASH_MONITOR
08-01T14:01:12      0      0        0          0       1       0   0.027 monitor.IBCONF
08-01T14:01:12      0      0        1          0       1       0   0.055 monitor.LICENSE
08-01T14:01:12      0      0        0          0       1       0   0.028 monitor.MARIADB_CONFIG
08-01T14:01:12      0      0        0          0       1       0   0.060 monitor.MARIADB_CONFIG_TYPE
08-01T14:01:12      0      0        0          0       1       0   0.028 monitor.MARIADB_MONITOR_CONNECT
08-01T14:01:12      0      0        0          0       1       0   0.034 monitor.MARIADB_MONITOR_DML
08-01T14:01:12      0      0        0          0       1       0   0.034 monitor.MARIADB_MONITOR_SINGLE
08-01T14:01:12      0      0        0          0       1       0   0.035 monitor.MARIADB_MS_SINGLE
08-01T14:01:12      0      0        0          0       1       0   0.036 monitor.MARIADB_TRAFFIC_STATISTICS
08-01T14:01:12      0      0        2          0       1       0   0.045 monitor.MARIADB_TYPE

检查主从

通过DSN连接从库,首先在主库中创建相关的表和数据库。

create database percona;
CREATE TABLE `percona`.`dsns` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`parent_id` int(11) DEFAULT NULL,
`dsn` varchar(255) NOT NULL,
PRIMARY KEY (`id`)
);

插入可以连接从库的用户名、密码、端口等信息

use percona;
insert into dsns(dsn) values('h=192.168.20.,P=3306,u=repl,p=123');

DSNs记录 dsn 列格式如 h=REPLICA_HOST,u=repl_user,p=repl_pass

检查命令如下:显示所有检查信息,可以通过指定--replicate-check-only来只显示数据不一致的表信息。

[root@BigData ~]# pt-table-checksum h=192.168.20.5,u=root,p=Sanshi_408,P=3306 --databases=monitor --recursion-method dsn=h=192.168.20.6,D=percona,t=dsns --no-check-binlog-format
Checking if all tables can be checksummed ...
Starting checksum ...
Replica 18c-dg is stopped.  Waiting.   ---slave进程关闭,无法检查。需要手动启动。
Replica 18c-dg is stopped.  Waiting.
Replica 18c-dg is stopped.  Waiting.
Replica 18c-dg is stopped.  Waiting.
Replica 18c-dg is stopped.  Waiting.
Replica 18c-dg is stopped.  Waiting.
            TS ERRORS  DIFFS     ROWS  DIFF_ROWS  CHUNKS SKIPPED    TIME TABLE
08-01T14:19:40      0      0        8          0       1       0 178.474 monitor.B_HOST
08-01T14:19:41      0      0       23          0       1       0   1.148 monitor.B_MONITOR_ITEM
08-01T14:19:41      0      0        7          0       1       0   0.185 monitor.B_SEND_MAIL
08-01T14:19:41      0      0        1          0       1       0   0.105 monitor.B_SEND_MAIL_FREQ
08-01T14:19:41      0      0        7          0       1       0   0.082 monitor.B_TRIGGER_RULE
08-01T14:19:41      0      0       14          0       1       0   0.053 monitor.B_WARN_CONFIG
08-01T14:19:41      0      0       46          0       1       0   0.081 monitor.B_WARN_INFO
08-01T14:19:41      0      0       14          0       1       0   0.060 monitor.B_WARN_ITEM
08-01T14:19:41      0      0        3          0       1       0   0.058 monitor.B_WARN_LEVEL
08-01T14:19:41      0      0        1          0       1       0   0.055 monitor.B_WARN_NOTICE
08-01T14:19:42      0      0        0          0       1       0   0.062 monitor.DATA_GROUP
08-01T14:19:42      0      0        0          0       1       0   0.083 monitor.DATA_GROUP_HOST
08-01T14:19:42      0      0        8          0       1       0   0.044 monitor.DB_GROUP
08-01T14:19:42      0      0       17          0       1       0   0.051 monitor.DB_VERSIONS
08-01T14:19:42      0      0        0          0       1       0   0.060 monitor.FLASH_INFO
08-01T14:19:42      0      0        0          0       1       0   0.056 monitor.FLASH_MONITOR
08-01T14:19:42      0      0        0          0       1       0   0.048 monitor.IBCONF
08-01T14:19:42      0      0        1          0       1       0   0.056 monitor.LICENSE
08-01T14:19:42      0      0        0          0       1       0   0.061 monitor.MARIADB_CONFIG
08-01T14:19:42      0      0        0          0       1       0   0.047 monitor.MARIADB_CONFIG_TYPE
08-01T14:19:42      0      0        0          0       1       0   0.069 monitor.MARIADB_MONITOR_CONNECT
08-01T14:19:42      0      0        0          0       1       0   0.061 monitor.MARIADB_MONITOR_DML
08-01T14:19:42      0      0        0          0       1       0   0.043 monitor.MARIADB_MONITOR_SINGLE
08-01T14:19:42      0      0        0          0       1       0   0.045 monitor.MARIADB_MS_SINGLE
08-01T14:19:42      0      0        0          0       1       0   0.042 monitor.MARIADB_TRAFFIC_STATISTICS
08-01T14:19:42      0      0        2          0       1       0   0.041 monitor.MARIADB_TYP
...

列名说明:

  • TS:时间戳
  • ERRORS:错误、警告数量
  • DIFFS:主从不同的chunk数量。如果指定了--no-replicate-check那么该列永远为0.如果指定了--replicate-check-only,那么只显示数据不一致的表。
  • ROWS:表的行数
  • CHUNKS:表分拆分成chunk的数量
  • SKIPPED:由于以下问题导致跳过的CHUNK数量
    * MySQL not using the --chunk-index
    * MySQL not using the full chunk index (--[no]check-plan)
    * Chunk size is greater than --chunk-size * --chunk-size-limit
    * Lock wait timeout exceeded (--retries)
    * Checksum query killed (--retries)
    
  • TIME:检查该表所用时间
  • TABLE:表名

默认情况下,会创建一个percona.checksums表用于存储检查信息。除了可以通过查看输出信息来验证表的数据同步情况下,也可以通过查询percona.checksums中数据来查看,如下:

SELECT db, tbl, SUM(this_cnt) AS total_rows, COUNT(*) AS chunks
FROM percona.checksums
WHERE (
 master_cnt <> this_cnt
 OR master_crc <> this_crc
 OR ISNULL(master_crc) <> ISNULL(this_crc))
GROUP BY db, tbl;

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