Amazon’s DynamoDB is a wonderful product – scalable, durable, fast, with predictable latency numbers unlike SimpleDB. However, the only gripe I have with DynamoDB is that there is no built-in support for a query language, which makes life rather difficult when you want to perform a query or a scan against the data you have in DynamoDB.
Whilst the standard AWS SDK for .Net provides a number of different ways to perform queries and scans:
- using the low-level AmazonDynamoDBClient
- using the Table helper class
- using the DynamoDBContext ORM
none of these ways are easy to use and the few attempts to use them in our codebase left a bad taste in my mouth and an external DSL is desperately needed to make it easier to express the query we’d like to perform against data stored in DynamoDB.
It is because of these limitations that I decided to add a SQL-like external DSL on top of existing functionalities to make it easier for .Net developers to work with DynamoDB.
Having spent a couple of weekends I have put together a simple library called DynamoDb.SQL, which you can download and try it yourself from Nuget here. This library adds an external DSL on top of the existing functionalities of the .Net AWS SDK and allows you to query and scan DynamoDB using natural, SQL-like syntax.
Using this syntax, a query can be expressed with the general format:
where @HashKey and @RangeKey are special keywords to mean the hash and range key in your table, and operator can be one of the allowed comparison operators for a query request :
=, >=, >, <=, <, BEGINS WITH and BETWEEN .. AND ..
Similarly, a scan can be expressed with the general format:
where operator1 to operatorN can be one of the allowed comparison operators in a scan request :
=, !=, >=, >, <=, <, CONTAINS, NOT CONTAINS, BEGINS WITH, IS NULL, IS NOT NULL, BETWEEN .. AND .., and IN (…)
To learn more about the syntax and how to use DynamoDb.SQL, take a look at the Getting Started guide here.
DynamoDB – Querying and Scanning using high-level DynamoDBContext