Azure Table Vs MongoDB on Azure

Table Storage is a core Windows Azure storage feature, designed to be scalable (100TB 200TB 500TB per account), durable (triple-replicated in the data center, optionally georeplicated to another data center), and schemaless (each row may contain any properties you want). A row is located by partition key + row key, providing very fast lookup. All Table Storage access is via a well-defined REST API usable through any language (with SDKs, built on top of the REST APIs, already in place for .NET, PHP, Java, Python & Ruby).

MongoDB is a document-oriented database. To run it in Azure, you need to install MongoDB onto a web/worker roles or Virtual Machine, point it to a cloud drive (thereby providing a drive letter) or attached disk (for Windows/Linux Virtual Machines), optionally turn on journaling (which I'd recommend), and optionally define an external endpoint for your use (or access it via virtual network). The Cloud Drive / attached disk, by the way, is actually stored in an Azure Blob, giving you the same durability and georeplication as Azure Tables.

When comparing the two, remember that Table Storage is Storage-as-a-Service: you simply access a well-known REST endpoint. With MongoDB, you're responsible for maintaining the database (e.g. whenever MongoDB Inc (formerly 10gen) pushes out a new version of MongoDB, you'll need to update your server accordingly).

Regarding MongoDB Inc's alpha version pointed to by jtoberon: If you take a close look at it, you'll see a few key things:

• The setup is for a Standalone mongodb instance, without replica-sets or shards. Regarding replica-sets, you still get several benefits using the Standalone version, due to the way Blob storage works.
• To provide high-availability, you can run with multiple instances. In this case, only one instance serves the database, and one is a 'warm-standby' that launches the mongod process as soon as the other instance fails (for maintenance reboot, hardware failure, etc.).

While 10gen's Windows Azure wrapper is still considered 'alpha,' mongod.exe is not. You can launch the mongod exe just like you'd launch any other Windows exe. It's just the management code around the launching, and that's what the alpa implementation is demonstrating.

EDIT 2011-12-8: This is no longer in an alpha state. You can download the latest MongoDB+Windows Azure project here, which provides replica-set support.

For performance, I think you'll need to do some benchmarking. Having said that, consider the following:

• When accessing either Table Storage or MongoDB from, say, a Web Role, you're still reaching out to the Windows Azure Storage system.
• MongoDB uses lots of memory for its own cache. For this reason, lots of high-scale MongoDB systems are deployed to larger instance sizes. For Table Storage access, you won't have the same memory-size consideration.

EDIT April 7, 2015If you want to use a document-based database as-a-service, Azure now offers DocumentDB.

I have used both.

Azure Tables : dead simple, fast, really hard to write even simple queries.

Mongo : runs nicely, lots of querying capabilities, requires several instances to be reliable.

In a nutshell,if your queries are really simple (key->value), you must run a cost comparison (mainly number of transactions against the storage versus cost of hosting Mongo on Azure). I would rather go to table storage for that one.If you need more elaborate queries and don't want to go to SQL Azure, Mongo is likely your best bet.

I realize that this question is dated. I'd like to add the following info for those who may come upon this question in their searches.

Note that now, MongoDB is offered as a fully managed service on Azure. (officially in Beta as of Apr '15)

See:http://www.mongodb.com/partners/cloud/microsoftorhttps://azure.microsoft.com/en-us/blog/announcing-new-mongodb-instances-on-microsoft-azure/

See (including pricing):https://azure.microsoft.com/en-us/marketplace/partners/mongolab/mongolab/