While running pt-table-checksum on a machine with singe-master, single-slave setup, I *sometimes* run into a bunch of these errors:
Error checksumming table scheme_name.table_name: Illegal division by zero at /usr/bin/pt-table-checksum line 7950.
11-06T17:47:56 1 0 141 1 0 0.004 scheme_name.table_name
In a test/lab setup, copied over the whole database, I was unable to reproduce this. It seems the production enviroment with older/slower hardware with more load as a result triggers this. Re-running on the same server doesn't always trigger it, so it seems. Because it is usually a meaningless error for the sysadmin and it will be checksummed in the next run anyway, it generates a lot of unwanted noise in the cron output.
Ubuntu 12.04.1 running plain MySQL server 5.5.28-0ubuntu0.12.04.2, Percona toolkit 2.1.5 (upstream repository), ~ 8600 InnoDB tables and < 100 MyISAM.
The simplest table affected here:
CREATE TABLE `table_name` (
`col1` int(10) unsigned NOT NULL DEFAULT '0',
`col2` int(10) unsigned NOT NULL DEFAULT '0',
KEY `key1` (`col1`),
KEY `key2` (`col2`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 ROW_FORMAT=DYNAMIC