I do things with data platforms professionally. Occasionally, I write about things here.

Mandatory EVE Disclaimer

This posts relates to EVE Online, a space MMORPG. It had a unique sandbox and relatively unforgiving nature. I had a brief (really, extended) time playing EVE that produced many memorable moments - but there's a few unique ones that stand out. If you're not familiar with it, posts in the EVE Online category may not be as interesting to you.

Monthly Active Users Calculation

Given a table with the below definition.

user_actions Table: Column Name Type user_id integer event_id integer event_type string ("sign-in, "like", "comment") event_date datetime

Write a query that will return "Monthly Active Users" (MAU) for each month in the table.

Around 2010, OLAP cubes were a common way to support analytics. They were the fastest way to do interactive analysis over a fixed set of "dimensions".

One of the popular solutions was Microsoft's SQL Server Analysis Service, or SSAS. SSAS was well integrated with the microsoft ecosystem (SQL Server, SSIS, etc) and was a popular choice for many companies.

Context

At Wayfair from 2015-2020, I spent a significant amount of time leading teams that built and leveraged Kronos, a generalized orchestration engine for data warehouses. The engine ended up having quite significant adoption, though it was too tightly coupled to Wayfair technology to be a viable open-source option. Post Wayfair, I realized that though I had a good sense of how Kronos fit into the broader landscape of data orchestration tools - of the time Oozie, Airflow, Luigi, SSIS, and more - and the tools of the future - DBT, etc - there were many who worked extensively with the platform who might not and could benefit from knowing how what they learned fit into the broader landscape.