Mongos, anybody?

Unless you’ve been living under/in the proverbial rock/hole-in-the-ground, you’ve heard of this thing called MongoDB. It’s one of the biggest flavors of NoSQL database systems out there – specifically, it’s a “document DB”, which means it stores semi-structured data in the form of JSON documents, grouped into collections, grouped into (of course) DBs.

Now, I’m a Windows guy. SQL Server & Windows Server are my comfort zones. I like GUIs, but I’m ok with a command line too. PowerShell has become my friend good acquaintance. But every once in a while, we have to step outside our comfort zones, no? So when I was told “hey, you’ve got to get a handle on managing these MongoDB instances that we’ve got running on servers so-and-so, as part of this ‘Imaging system’ application”… I thought “Hahaha…”, but what came out was “Sure thing!”  Something a bit like this:

(courtesy of DBA Reactions)

So the first order of business was to decide on a MongoDB “GUI” – a Windows app that could at least connect-to and give me a visual overview of the running MongoDB instances (properly referred to as a mongod, stemming from the Linux term “daemon”, which on the Windows side is basically like a process or service). I tried both the “official” desktop app from the big org, MongoDB Compass, and a neat open-source tool called Robomongo.

And I actually like them both, for different reasons; most of which can probably be attributed to my lack of depth with the technology, but hey. Anyway, Compass is really nice in that it gives you this kind of statistical overview of the collections in your DBs, performing some basic aggregates on a 10% or 1k sample of the collection documents to give you a graphical 40-thousand-foot view of the data. But where it breaks down for me is that little “query” bar, which is just an empty pair of curly-braces. It’s only for “selecting” (finding, querying); no other operations to see here. So we can’t manipulate our data with it, but it’s definitely great for viewing!

 

Whereas with Robomongo, I can right-click on the DBs/collections and do very simple things like “show documents”, “show statistics”, etc. And it actually writes the equivalent mongo shell command for me to poke at; say, to inject more logic to the find to get something specific or to write a new command or two as I read thru the docs and learn things like aggregates, indexes, and whatnot. Being a shell, it allows us to write or update data as well as read it.

But alas, GUIs will only take you so far. This is a tech born & bred on the command-line, so to really dig into it, I needed to let go of the mouse. And the mongo shell was actually pretty straightforward! A couple visits to their docs pages & some visual verification by using the GUI tools to check my work, and things were starting to come together. And even for a complete Javascript noob like me, the command syntax was straightforward enough. Soon I was configuring a replset and mongodump/mongorestore-ing and re-syncing a replica after purging some old stale collections.

Even though it’s a CLI/Linux flavored technology, it works perfectly fine in Windows… Except for one thing.  So, you install it as a service, and you typically start & stop services using net start & net start and as long as your service’s CLI arguments are all correct, you should be good — in theory! Trouble is, the service tends not to stop gracefully. So I found that, instead, the following command was more useful: mongo admin --eval "shutdownServer()". This uses the actual mongo shell to send the native shutdown command to the mongod, instead of relying on the Windows services gymnastics to do it correctly.

It just goes to show, dear reader, that you’ve got to get your hands dirty and try out new technology before dismissing it as “not my job” or “somebody else’s problem”.

PS: Nope, that’s not Compass’s logo or anybody else’s; I made it meself, with good old Paint.NET!

Drafted with StackEdit, finished with WordPress.