I love finding out new things about MySQL. Last week, I stumbled on a query that had the phrase “SOUNDS LIKE” in it. Sounds made-up, right? Turns out MySQL is using a known “soundex” algorithm common to most databases, and popular in use cases in geneaology.

The basic idea is that words are encoded according to their consonants. Consonants that sound similar (like M and N) are given the same code. Here’s a simple example:

(“soundex” and “sounds like” are different ways of doing the same thing in these queries)

MariaDB> select soundex("boom");
+-----------------+
| soundex("boom") |
+-----------------+
| B500            |
+-----------------+

MariaDB> select soundex("bam");
+----------------+
| soundex("bam") |
+----------------+
| B500           |
+----------------+

MariaDB> select soundex("bin");
+----------------+
| soundex("bin") |
+----------------+
| B500           |
+----------------+

…

A broken VIEW was caused by the view’s definer being non-existent. In this particular system, backups are done by replicating all the machines (production, development, test, etc) to one server and doing cold physical backups off that server, which currently has 12 instances running.

So in order to find on what machine the user might still be defined, I went to the backup server. All the data directories are in one path, ie:

instance 1 has a datadir of /data/mysql/instance1
instance 2 has a datadir of /data/mysql/instance2

Now, the unix tool strings can be used against many types of files. In particular, though, you can use strings on the mysql/user.MYD file to see the username, host, and password hash. (note that strings only shows strings longer than 3 characters, so if your host or username is 3 characters or less, it will not show up in the output of strings. You …