[koolba]

> Events are stored in DynamoDB. We use mongo for "core" data like accounts, feature flags, etc, but none of the high throughput stuff touches MongoDB.

Curious, why the choice of MongoDB for anything? In my mind "core" data tends to be very structured and require true transactional updates, both of which are cornerstones of a relational database (cough Postgres). Sure it's possible to use MongoDB, but what was the driver for it?

[jkodumal]

We had a lot of operational experience with Mongo from our previous jobs at Atlassian, and started out storing almost everything in Mongo. As we scaled out, we migrated all of our high volume data into other stores-- analytics into DynamoDB, searchable data into ElasticSearch, etc.

The last remaining piece is our core data, and there's no strong push to move it out of Mongo.

[kornish]

So, just to clarify, you use DynamoDB and ElasticSearch as primary datastores for those types of data and don't replicate data from Mongo into them?

[jkodumal]

That's mostly right. We don't use ES as a primary datastore, though.