The skiptree is a great example of constraint-driven invention - you didn't set out to build a new data structure, you had a specific constraint (BigQuery's poor point lookups) and the solution naturally emerged from combining two existing ideas. The part about writing a JavaScript compiler to generate kilobyte-scale SQL queries is underappreciated, too. Most engineers would have switched databases, but building a compiler when output is too complex to write by hand is almost always the right call.