I’ve mentioned in the past how you can configure the MongoDB Java driver output from Java. Most Clojure applications that use MongoDB use a database driver that wraps the official MongoDB Java driver. I personally use monger for a lot of my projects, but also occasionally created my own wrapper. The methods described in this post should be applicable to other Clojure MongoDB drivers as long as they wrap the official MongoDB Java driver. They should also work if your application directly wraps the MongoDB Java driver itself rather than using a more idiomatic driver.

MongoDB has a handy command to rename a collection, db.collectionName.renameCollection(). There is currently no equivalent to rename a database. Now if we accept that from time to time, one positively, absolutely just has to rename a database in MongoDB, well, there are a couple of options. Unfortunately they aren’t quite as straight forward as single MongoDB command. All methods for renaming a database in MongoDB also take a fair amount of time and/or disk space to complete. Keep this in mind when you try to use any of them.

I’ve been meaning to post this link for quite a while now but keep forgetting to do so. If you are planning to store geospatial data in MongoDB, the database offers you a variety of ways to deal with geospatial-specific data storage and queries.

I gave an introductory talk on this subject at MongoDB World 2017 and you can find a recording of the talk here.

Disclaimer: I work for MongoDB as a Consulting Engineer and this is my personal blog. Any opinions expressed herein are entirely my own and do not reflect opinions of my employers, past present or future.

RHEL 7 – and CentOS 7, which I used for this test – use tuned.conf to set a lot of system settings. Several of the tuned settings affect MongoDB’s performance; some are important enough that mongod actually triggers startup warnings. The main setting is transparent huge pages, which is a setting that does not work very well with databases in general.

The MongoDB documentation already describes how to disable Transparent Huge Pages (aka THP) using tuned.conf, but there are several other settings that mongod tends to warn users about if you run it on an out-of-the-box CentOS 7.

I will show you how to enable logging in the MongoDB Java driver and also how to set and change the log level. The official mongoDB Java driver uses java.util.logging as its default logging framework or sl4j if the latter is present. It can be very useful to enable logging in the MongoDB drivers to trace how the driver is interacting with the database.