MySQL

So, you have a binlog. You want to find out something specific that happened inside of it. What to do? mysqlbinlog has some neat features, which I thought we would look at here. I should first explain what mysqlbinlog really is. It is a tool that lets you analyze and view the binlogs/relaylogs from mysql, which are stored in binary format. This tool converts them to plaintext, so that they’re human-readable. For the first tip, let’s start with the –read-from-remote-server option, which allows you to examine a binlog on a master server in order, perhaps, to dump it onto your slave and compare master/slave logs for potential problems*.

The Maatkit toolkit is a real blessing for the MySQL DBA. And while its documentation is pretty good, in some cases it’s necessary to read carefully a second and third time to make sure you are not missing an important piece of information. In this article I will comment on mk-table-chksum and mk-table-sync. My comments are mostly aimed at those DBAs who are considering using these utilities with medium or larger-sized databases.

After I moved back to Europe and Malta in order to set up our operations here, I was approached by a old friend of mine who wanted to know how to add a UNIQUE constraint and remove duplicates on a table, while keeping the newest records. He had been trying with ALTER TABLE but ran into problems as the older values were taken. To help him out, I first solved it based on his original idea, and then figured I would post a small note about the solution here.

I recently needed to set up multiple MySQL servers on a test computer to simulate a master-slave setup. I had never done this before, so I think it might be useful for others if I documented what occurred.