Migrations are one of the best features of Rails. Although some folks prefer pure SQL rather than Rails migration DSL, I don’t know of anyone who dislikes the idea of a versioned schema that can evolve in a controlled and repeatable fashion.
But because the concept of database migrations is such a powerful one, it’s tempting to jam any old change that affects the database into a new migration and run
rake db:migrate to make it happen. I’ve been guilty of a bit of this in the past, and I’ve joined some projects that did other ugly things in migrations. In the process I’ve learned the hard way that there are some things you must never do in a migration or they will come back to haunt you later. Here they are.
Continue reading “Rails Migration Antipatterns and How To Fix Them”
The details of the various mount options for the ext3 filesystem are fairly well documented, but as with many things in the Unix world, knowledge is far easier to come by than wisdom. That’s a pithy way of saying that I had to do some digging to find recommendations, as opposed to explanations. So here are my recommendations for ext3 users (which encompasses the majority of the Linux-using world, as far as I can tell).
Continue reading “Recommended mount options for ext3”
Sphinx search is pretty new, and as a result I was unable to find a nice convenient package for it for CentOS 5.1. This is problematic since there is no init script included with the source tarball, and the issue of updating the index is the sysadmin and developer’s problem, and cannot be configured to simply update the index when the data changes.
Continue reading “Sphinx Search init script for Centos 5.1”
SELinux is a recently added security system that’s installed by default with CentOS 5.1 (and Red Hat Enterprise Linux 5, and others). Since it’s newer than the classic “Discretionary Access Control” Unix security model, it’s not nearly as well documented, and unfamiliar to many. I had never even heard of it until this week.
After a lot of reading about it, and debating disabling it entirely, I figured out how to do some minor SELinux customization to fit my needs for a MySQL database server. Hopefully this will help folks who are in a similar situation.
Continue reading “Making SELinux allow a nonstandard MySQL port number on Centos 5.1”
There’s a new crop of databases that has appeared lately, under the rubric of “document databases”, and there’s quite a lot of enthusiasm for them given that they tend to be slow and very feature-poor compared to the SQL RDBMSs that are the typical persistence mechanism for web applications. What’s mainly appealing about them is that they are easy to use, and theoretically quite scalable, compared to the traditional “one big SQL database server” approach.
Continue reading “Document Databases – New Kids on an Old Block”