alt Hacker News> Time-Travel Queries: Query historical data at any point in time:
The example here looks like it may be storing the full history of transactions? Is that right? That's a pretty high cost to pay for something that's not touted as a marquee feature.
I'm working on a DB[1] that stores full transaction history but it's so that I can support decentralized synchronization. It's in service of my marquee feature so I need to pay the cost of storing history, but I'm surprised that Stoolap also seems to be doing it for a local embedded database.
I would imagine (but haven't looked at it at all) that it's a byproduct of an append only data format. Then having a historical PoV is cheap - you simply disregard changes after a certain time.
Append-only has many other benefits, including zero contention between many readers and (single) writers. In the vanilla version, writers still contend though.