Database Finder

“What should I store this in, and how should I access it?” Answer the questions; the finder recommends a data model, an index, or an isolation choice — starting from the simplest option and explaining why it rejected the alternatives.

Six questions in the order a senior engineer asks them. Any one can end in "no".

Step 1
Is this query frequent?

An index is paid for on every write and repaid on every read.