Example task: Multiply the table holidays between several stages. Open two terminals: shell-for stage_1 shell-for stage_2...

Trick: Do not use convert but mogrify: mogrify -resize 50% * This overwrites the original image file. In contrast, convert writes...

When you work in the MySQL console and you want to see which database is used, type: SELECT database();

Interesting interview with DHH, where he talks about how they made the new Basecamp feel very fast without using a...

This article describes how to reset MySQL's or MariaDB's root password on your workstation. It's meant for...

Nice list of icon sets that come in the form of fonts. I recommend Font Awesome.

For string columns, MySQL indexes the left side of a string. That means an index can speed a like query...

So you got this error, even though your Gemfile bundles mysql2: !!! Missing the mysql2 gem. Add it to your Gemfile...

The next version of MySQL will include a built-in memcached daemon. This daemon can quickly get and set key/value...

Unless you changed the default, this will be 16 MB: mysql> SHOW VARIABLES WHERE Variable_name="max_allowed_packet"; +--------------------+----------+

Sometimes, you may want to open up a second database connection, to a read slave or another database. When doing...

Take care in queries where multiple AND or OR operators are used. In doubt, always use braces to enforce precedence...

This will make MySQL log all received queries so you can see for yourself what happens on the database level...

ActiveSupport >= 3 has Date.parse('2011-02-10').beginning_of_quarter #=> 2011-01-01 Date.parse('2011-02-10').end_of_quarter...

If you upgrade to the mysql2 gem, you will run into the problem that the server's database.yml (which is...

Some advice for bulk loading many records into InnoDB and finishing before the sun burns out. Use with care.

MySQL version 5.1 comes with an alternative, faster InnoDB implementation (called "InnoDB Plugin"). Switching is easy: Stop your mysqld with...

When requests arrive at the application servers simultaneously, weird things can happen. Sometimes, this can also happen if a user...

How to call routes, make requests and try out helpers from the Rails console.

An association defined with has_many :through will return the same record multiple times if multiple join models for the...

This is for you if Passenger gives you the following useless error message. Passenger encountered the following error:\ The application...

When talking to your MySQL server via a mysql shell, you can terminate queries by ; or \G -- the latter gives...

Usually you don't need to, but when you want to see which queries your MySQL server currently needs to...

When you do a script/dbconsole -p, your MySQL shell will already be using UTF-8. When you call it yourself...