We have a dozen websites mostly running WordPress, and one Drupal website on Digital Ocean with a 1GB instance. The server was running flawlessly for 6 months, and then MySQL starts to crash every few days unexpectedly with the following error in the MySQL error log.

MySQL documentation states the following with respect to the "character set" and "collation" of the data storage in the database.

I've had a chance to with a Postgres database and came across a table with two primary keys. This intrigues me to look up a definition of primary and unique key. I always thought there would only be one primary key in a table, and the values have to be unique. But, what I saw in the PostgreSQL v8.1.23 was something otherwise. It allowed duplicate entries, and also allowed multiple primary keys in a table. Is this possible? Yes, it's called composite Primary Keys. Composite primary keys (multiple primary keys) makeup uniqueness in a table row -- which means composite primary keys work together to provide uniqueness.

There was an error with one of our applications, and I needed to find table rows with duplicate values. The table column was not defined to have a unique index, but we weren't anticipating duplicate values. I needed an easier way to identify duplicate values in a table with a simple SQL statement.