Update and friends
This is the final part of the series where I convert Amazon’s Getting Started to Clojure with Faraday. If you’ve just arrived, the previous parts were:
This part will correspond to steps 7 and 8 of the Getting Started guide. Let’s move on to updating and deleting data!
In part 1 we went over the basic table creation operations, as well as writing data, and on part 2 we looked at getting, querying and scanning data.
We’ve only been working with the primary key so far, but often we’ll want to get data using a secondary index. On this part we’ll follow step 6 of Amazon’s Getting Started. We’ll see how to create, query and scan them, as well as how Faraday handles these asynchronous calls.
The story so far
On Part 1 we went over the basic operations - creating a table, checking its status, getting data in and performing a simple retrieval.
We’ll now look into various ways of retrieving items, including querying, scanning, and using projections to get only a few properties.
DynamoDB and Clojure
There are two main options of accessing DynamoDB in Clojure right now - Amazonica, which provides a Clojure client through reflection that’s comprehensive but a direct translation of Amazon’s; and Faraday, which does not take the reflection approach and provides a simpler, more succinct access than one would otherwise get.
Both have a paucity of examples. Amazonica can probably better get away with it since it gets to piggy-back on the AWS examples out there, but Faraday’s tests have been growing and can double as examples.
I started with Faraday, since its more concise API was more appealing and I liked its reasonable defaults. In the process, I’ve added some missing functionality, expanded tests, and noticed that the examples from Amazon’s Getting Started tutorial weren’t fully covered.
Let’s fix that.
Or, apples vs. papaya salad.
Short version: I’ve moved Tropology to PostgreSQL for performance reasons, and because after some evaluation, Neo4j wasn’t as good a fit as it seemed at first blush.
You may want to start by catching up with the other Tropology articles.