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Comment by ams6110 | Hacker News Reader

Thanks. I read the entire "Documentation" page and still didn't feel confident that I understood what this really was. "Event sourcing" to me implies that it's generating events.

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Event Sourcing is a technical term, it's the idea that instead of mutating your database, you should instead have a log and insert a new log entry saying that you changed this value to that, etc. The idea is that this helps you do cool stuff like temporal queries (i.e. make a query "as the entire database looked like a month ago") or look at historical values and changes of things. This matters a lot in some fields. Of course then there's the matter of how to do this efficiently. You can build event sourcing on top of a regular RDBMS but if there is database-level support (as in PumpkinDB), then maybe some things are more efficient. Read more:

https://martinfowler.com/eaaDev/EventSourcing.html

This sounds like my (probably wrong/incomplete) understanding of Datomic?

I believe you could use Datomic for event sourcing, though it wasn't explicitly designed for the job and may not be the best choice depending on the requirements of your system as a whole. Bobby Calderwood at Capital One has a talk on a system which includes both event sourcing (using Kafka, IIRC) and Datomic:

https://speakerdeck.com/bobbycalderwood/commander-better-dis...

Nice, thank you.

Virtually every db works like that under the hood. They expose it differently, though. Kafka has nothing but log, for example.

e.g. https://dev.mysql.com/doc/refman/5.6/en/binary-log.html

They do but it's usually not exposed in a useful way. Postgres once had this feature... https://www.postgresql.org/docs/6.3/static/c0503.htm

We actually expose something to support event sourcing: https://www.postgresql.org/docs/current/static/logicaldecodi... - although that's very different from the old time travel feature.

Edit: missing word

We are definitely looking to improve the documentation. This is 0.1, after all.

This project was started as a backend for a lazy event sourcing approach (https://blog.eventsourcing.com/lazy-event-sourcing-ed7e59007... , https://m.youtube.com/watch?v=aqv8d1pjmU8) and beyond.

The idea behind it is that it provides primitives for building systems that are designed around immutable events, journals, indexing, etc. Hence the current positioning. We thought it would be useful to be targeting fairly narrowly early on.

Either way, we will definitely need to expand on that in our materials

Amazing looking project! I've been daydreaming about using LMDB's memory mapping to provide a flexible low level db primitive for quite a while, figuring a combo of erlang like actors and flexible data scripting would be killer. Needless to say I love the design.

Any thoughts on whether this could be used to implement a Q/kdb+ like computation system? Seems like PumpkinScript could be extended with a library of computational array primitives. (https://news.ycombinator.com/item?id=13481824)

That being said, it'd be great to be able to read how the "actor" system is implemented. The documentation alludes to actors and pub/sub channels. Not sure I can help much at this time, but will keep an eye on it to see!

Well, its a fancy word. Thats basically what I took away from it. Also, I agree, read the whole doc and took way longer to understand what it does.

Clearly, they are smart, but bad copywriters :)

Please write better docs.

Doing our best, one step at a time! It's clear to me that we haven't spent enough time on documentation yet. The whole project is only 3 weeks old and our initial focus was to get a working version out with some level of documentation (a goal that we somewhat attained, I believe)

Fair enough. I'm gonna be done this shitty program and have a piece of papers with some fancy seal on it in a couple of months. I'd be happy to contribute.

Bookmarked until then.

Also, if this topic is interesting to anybody who's good at writing, we are very open to contributions of all kinds!

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