Archive for the ‘MongoDB’ Category

A dockerized mongod instance with authentication enabled

Here’s just a quick walkthrough showing how to create a dockerized instance of a standalone MongoDB instance. First, from within a terminal, create a folder to hold the Dockerfile… ?View Code BASHmkdir Docker_MongoDB_Image cd Docker_MongoDB_Image touch Dockerfile Edit the Dockerfile… ?View Code BASHvi Dockerfile Enter the following text. You may wish to modify the file […]

MongoDB: Making the most of a 2 Data-Centre Architecture

There’s a big initiative at my employers to improve the uptime of the services we provide. The goal is 100% uptime as perceived by the customer. There’s obviously a certain level of flexibility one could take in the interpretation of this. I choose to be as strict as I can about this to avoid any […]

MongoDB and the occasionally naughty query

It’s no secret that databases like uniqueness and high cardinality. Low cardinality columns do not make good candidates for indexes. A recent issue I had with MongoDB proved that NoSQL is no different in this regard. The MongoDB Query Planner is quite simple and works as follows (simplified)… If there are no usable indexes; perform a collation […]

A few Splunk queries for MongoDB logs

Here’s a few Splunk queries I’ve used to supply some data for a dashboard I used to manage a MongoDB Cluster. Election events If any MongoDB elections happen at 3AM on a Wednesday night I want to know about it. This query, added to a single value panel allows me to do this easily… host=mongo* […]

Working with the PlanCache in MongoDB

I’ve been working a little with the PlanCache in MongoDB to troubleshoot some performance problems we’ve been experiencing. The contents of the Plan Cache are json documents (obviously) and this isn’t great to work with in the shell. Here’s a couple of javascript functions I’ve come up with to make things a little easier. These […]