Should you write your own database?
We run a data pipeline that ingests very large product snapshots, turns them into downstream feed artifacts, and then keeps those feeds fresh with smaller incremental updates. The pipeline has a weekly "start from a new baseline" phase and an ongoing incremental phase layered on top of it. At a high level, the workflow looks like this: download very large source snapshots process them into a normalized internal representation persist the latest known state for each product build output partitions and feed fragments from that state continue applying smaller incremental updates until the next full weekly restart For a long time, the persistence layer in the middle looked like the boring part of the system. It was "just" a key-value store holding the latest state for a product, and the interesting work seemed to be in downloading, parsing, feed partitioning, and publishing. That assumption turned out to be wrong. As the system grew, the persistence layer became the d...