A frequently asked question about MySQL replication is "how do I know whether my slave is identical to the master?" Until recently there hasn't been a good way to know, but now you can compare all the data in your master to the data in the slaves and get a reliable yes-or-no answer. And you can do this online, efficiently, across many servers simultaneously. Read on to find out how.

I've just released three updates to tools in MySQL Toolkit. The updated programs are MySQL Query Profiler (major new features and helper script), MySQL Table Sync (bug fixes, documentation, features), and MySQL Table Checksum (minor sanity check enhancement).

When I wrote my first article on algorithms to compare and synchronize data between MySQL tables, Webyog's Rohit Nadhani left a comment on the article mentioning the SQLyog Job Agent, which has a similar function. Although I have been developing MySQL Table Sync essentially in isolation, I have been meaning to give SQLyog Job Agent a try. I recently did so, and then followed that up with an email conversation with Rohit. This article is about my experience using the SQLyog Job Agent from the command line, some thoughts on the algorithm as best I can deduce it, and benchmark results against MySQL Table Sync.

I wrote an article late last week about benchmark results for the two table-synchronization algorithms I've been implementing for the MySQL Table Sync tool. I've spent some time developing a test suite for the tool, and learned some really interesting things about the general problem of synchronizing tables.

MySQL Table Maintainer is a new utility to help you run table maintenance commands (ANALYZE, CHECK, OPTIMIZE, REPAIR) on your MySQL tables. It's part of the MySQL toolkit.

I've just released updates to all the tools in the MySQL Toolkit. The biggest change I made to most packages is using DBD to read MySQL's option files, though some packages got more significant updates.

MySQL Toolkit's Show Grants tool can now separate grants into individual statements, convert them into REVOKE statements, and help you remove users from a server, even if your server doesn't support DROP USER.

MySQL Table Sync efficiently finds and resolves data (not structural) differences between two MySQL tables, which may be on different servers. It offers two search algorithms to find the rows that differ, and several methods to bring the destination table into sync with the source.

MySQL Toolkit's Show Grants tool makes it easy to extract grants from a MySQL server in canonical form. You can use it to replicate grants between servers, diff grants, and avoid spurious changesets in version control systems.

I'm continuing to add new tools to the MySQL Toolkit. MySQL Deadlock Logger is for extracting and storing information about the latest recorded InnoDB deadlock. It's not only easy to view the information from the command line, it's dead simple to store it back into a MySQL table for analysis. I think most users will find it handy to create a cron job to record the deadlocks automatically for later analysis.