Judgement is made through the application of one or more biases.
Problematic judgement, including those indicating racism or sexism, comes when we apply irrelevant biases to the question at hand. Take a moment to skim Wikipedia’s list of cognitive biases, and you’ll wonder if it’s possible to make a well-informed judgement. Biases may be correlated but not causal, nakedly false stereotypes, weigh on our fear of risk, pull on our preference for familiarity; biases that don’t drive good judgements.
Incremental feature development against existing systems frequently involves rethinking and rebuilding existing components. If it’s possible, the easiest way to add support for your new feature is to introduce a new, optional attribute on a model (or in the case of a relational database, adding a NULLable column to an existing table, or adding a new table). Sometimes, though, that either isn’t possible, or wouldn’t be the best design going forward, given your new knowledge of the feature set of the product at hand. You’re left with the uncomfortable realization that the best design would be something completely different that isn’t backward-compatible with current systems.
When there are multiple systems that consume a given data model (say, a front-end webserver, an API, tons of cron jobs, and many backend daemons, like in the case of Twitter’s Ads systems), you can’t just “stop the world,” ALTER your tables, and deploy all the new code. That’s fine if it’s you and another nerd in a garage, but when you’ve got paying customers, you don’t want to give them an excuse to spend their money elsewhere.
In shutting down the AdGrok servers (talk about bittersweet…), I stopped the instances, but then remembered I wanted to shred the files first, so I clicked “start,” and was greeted by the following error:
The requested Availability Zone is no longer supported. Please retry your request by not specifying an Availability Zone or choosing us-west-1b, us-west-1c.
This last Friday I taught my “it really is rocket science” class to another hundred children (Kindergarten through 5th grade). Last year PTO Today wrote an article about Arts and Science day, and interviewed me. This year, the kids were great, I had tons of help, and the new rocket launcher designs let the kids experiment with different pressures and different launch angles. Good stuff!