What is M/DB?

M/DB is a "plug-compatible" alternative to Amazon's SimpleDB database. Outwardly, M/DB behaves identically to SimpleDB, being accessed through the same REST APIs and returning identical responses. The only difference in use is that REST requests are directed at a different domain name or IP address. Note that M/DB isn't a mock service: it's a true database.

M/DB version 1.0 Beta is compatible with Amazon Simple DB version 2007-11-07.

Why would I use M/DB?

M/DB will be of interest to anyone who is considering or already using SimpleDB, or is interested in using a simple, scalable database that avoids all the complexities of a relational database.

There are some interesting differences between M/DB and SimpleDB, as indicated in the table below:

Amazon SimpleDB	M/DB
Pay as you go	Free
Only available through Amazon Web Services	Can be used as a local database, or hosted within any cloud provider's service, including Amazon's EC2
1 kb maximum attribute size	Each attribute can be up to 32 kb
Maximum 10Gb per domain	Domain size limited only by your available disk storage
Maximum 250 million attribute name/value pairs per domain	No limit imposed, limited only by your available disk storage
Maximum of 100 domains per account	Unlimited domains
Maximum of 256 attribute name/value pairs per item	Unlimited name/value pairs per item
Maximum query execution time: 5 seconds	No limit imposed
No datatyping: text only. Integers and reals must be represented using leading zeros to ensure proper query comparisons	Dynamic datatyping. Integers and reals automatically collated and correctly recognised when queries are run
Very slow write performance, but this is due to multiple copies being made across multiple nodes for resilience and performance reasons	Very high-speed write performance, ideal for a locally hosted database. Replication is possible via the core DBMS technology
Massively scalable and fast querying	Highly scalable and fast querying
Zero maintenance	Very low maintenance

What are typical uses for M/DB?

M/DB can be used for a variety of reasons including the following:

• As a free and immediately available platform on which to learn how to use SimpleDB
• As a free platform on which to test SimpleDB applications
• To provide a live backup copy of a SimpleDB database, either locally or within a cloud service
• As a local, high-speed simple database, where the full features of an RDBMS are unecessary, and the complexity of setting up and maintaining an RDBMS is unwarranted
• In situations where the SimpleDB model is compelling, but its 1k attribute limit and/or its lack of datatypes make it too restrictive.

What database technology has been used for M/DB?

M/DB has been built on top of the free Open Source GT.M schemaless, hierarchical database engine. GT.M is a tried and tested technology that delivers very high performance and scalability.

How much does M/DB cost?

M/DB is provided free of charge, but it excludes any support. For support and consultancy services related to M/DB, contact Rob Tweed at rtweed@mgateway.com.

Is there an official M/DB forum or discussion group?

Yes. We've set up a Google Group to provide an online community forum for M/DB users, for news, self-help support, tips, examples etc. Feel free to join by clicking here.