[saghm]

I feel like I'm missing something, but the article started by talking about SQL tables, and then in-memory representations, and then on-disk representation, but...isn't storing it on a disk already what a SQL database is doing? It sounds like data is being read from a disk into memory in one format and then written back to a disk (maybe a different one?) in another format, and the second format was not as efficient as the first. I'm not sure I understand why a third format was even introduced in the first place.

[gz09]

Feldera is an incremental query engine, you can think of it as a specialized database. If you have a set of question you can express in SQL it will ingest all your data and build many sophisticated indexes for it (these get stored on disk). Whenever new data arrives feldera can instantly update the answers to all your questions. This is mostly useful when the data is much larger than what fits in memory because then the questions will be especially expensive to answer with a regular (batch) database.

Feel free to try it out, it's open source: https://github.com/feldera/feldera/