Anders posted a blog post about adding a new JSON data type to MariaDB. This made me remember my very first MySQL User conference, well, that and the next couple conferences actually. Why? Because at every conference (for awhile) I remember Brian Aker getting everybody into a room to discuss how to add a data type to MySQL. It was considered pretty much the quintessential example of how to start developing for MySQL because it touches a lot of the basic guts of the server.

The example that Brian always gave was a "hex" data type, so that you can store MD5 numbers using 128 bits of storage instead of 256. A human readable MD5 is a 256 bit string (32 characters) representing 128 bits of actual data. So storing MD5 values in the database (a very common thing) requires twice as much space as it should.

Now, …

Note: This article is about the WHERE extension to SHOW. I specifically use SHOW STATUS as an example, but WHERE is an extension to many SHOW statements.

Often DBAs will assess the health of a system by looking at some of the status variables returned by SHOW GLOBAL STATUS (specifying GLOBAL is important; remember that SHOW STATUS is the same as SHOW SESSION STATUS).

There are many status variables that SHOW GLOBAL STATUS returns. (SHOW GLOBAL STATUS on a Windows machine, MySQL version 5.0.67 returned 249, 5.1.22 returned 256 and 6.0.6-alpha returned 295 status variables!). I have used the SHOW STATUS LIKE syntax to help give me the output I really want, particularly when I forget the exact names of the status variables I am looking for.

But I did not know of a way to …