MongoDB, as I’ve mentioned before, is not without its warts. I’ve run into another, and it’s a nasty one. It turns out that if you perform count() on a query cursor that includes any conditions, even if those conditions are indexed, the operation takes O(n) time to run. In practice, I’ve found that this costs [...]
I’m a huge fan of MongoDB – after years in MySQL, Interbase, and Postgres SQL databases, it was quite a breath of fresh air to get to try a document database on for size. I’ve more or less adopted it as my default data store for web applications, due to a number of awesome features [...]
Users of MongoMapper may be familiar with mongrations, a Rails plugin to provide you with ActiveRecord-style migration tools for MongoDB. You don’t need them for schema changes, obviously, since MongoDB is schemaless, and you can define any changes you need to in your model. However, there are times that deploying a changeset will require some [...]
In part 1, I described how I located leaky Sets in MongoMapper by diffing the Ruby ObjectSpace with GDB. Today, I’m going to show you how to solve the problems that those sorts of diffs can reveal. In today’s example, we’re tracking leaky sets. In particular, a set is holding onto class references. We are [...]
If you’ve worked with MongoMapper for a while, you’ve probably noticed that in complex apps, there are horrific memory leaks in development that magically disappear in production mode. While this is all well and good, and it’s rather handy that things Just Work in production, don’t you wish you didn’t have to restart your app [...]
Introduction MongoDB 1.6 was released today, and it includes, among other things it includes support for the incredible sexy replica sets feature – basically master/slave replication on crack with automatic failover and the like. I’m setting it up, and figured I’d document the pieces as I walk through them. My test deploy is going to [...]
I was recently in need of a click mapping solution, and didn’t like most of the solutions I came across. They had huge dependency chains and were generally unwieldy, or they didn’t work that well, or they were external services that I had to pay for…until I ran across heatmapthing. Now we’re talking. Client-side rendering [...]
Since my initial experiments with GridFS and nginx-gridfs, I discovered a rather downer of a dealbreaker: compiling Passenger and nginx-gridfs into the same nginx binary makes nginx very unhappy. It hard-freezes (as in, blocks forever) when you request a GridFS file with Passenger enabled. Oops. So, I sat down and fixed gridfs-fuse. You can grab [...]
I’ve started playing with MongoMapper, and it’s quite excellent, but it does suffer very much from being young. There are lots of pieces missing that veterans of ActiveRecord will take for granted. I’ve been working around or patching them, for the most part, but I felt that my solution to `:counter_cache` deserved a post. In [...]
