4 ms·

It's good for really easy changefeeds. Eg in a multiplayer game scenario you might have several people touching rows in a table. Any client can construct a quer

It's good for really easy changefeeds. Eg in a multiplayer game scenario you might have several people touching rows in a table. Any client can construct a query filtering on their particular subset and trivially just say .Changes() and then get a fast, reasonably-robust changefeed with an image-then-deltas type interface. It's not particularly low latency and the latency is quite variable - so if you're timing requirements are of the millisecond order, look elsewhere.

jasondc 9y ago
Definitely valuable, as an aside, changefeeds are now in mongodb too: https://emptysqua.re/blog/driver-features-for-mongodb-3-6/#change-streams https://emptysqua.re/blog/driver-features-for-mongodb-3-6/#c...
- traverseda 9y ago
  and postgres!
  - Deimorz 9y ago
    Do you mean using LISTEN/NOTIFY, or some other method?
    - williamstein 9y ago
      Probably LISTEN/NOTIFY. I explain in detail how I migrated from RethinkDB to PostgreSQL using LISTEN/NOTIFY + tons of additional work here http://blog.sagemath.com/2017/02/09/rethinkdb-vs-postgres.html http://blog.sagemath.com/2017/02/09/rethinkdb-vs-postgres.ht... I've continued working on this codebase, even pushing commits this week like this one: https://github.com/sagemathinc/cocalc/commit/c20a62446b6e43cd56300d6f07808c76fd2d239b https://github.com/sagemathinc/cocalc/commit/c20a62446b6e43c...
      - Deimorz 9y ago
        Haha, I actually just finished skimming through that exact blog post because it was one of the first things that came up when I searched for "postgresql changefeed" to see if there was some other functionality for doing it that I didn't know about. I'll definitely need to go back and read it more thoroughly later and take a look through your code, thanks for the links.
    - chillydawg 9y ago
      You could do it with pglogical, if you're feeling particularly adventurous.
traverseda 9y ago
Games and chat are always popular examples, but I think it's really valuable for data-science. You can also "fill in" missing data. If you were writing a webscraper, you could make a service that looks for url objects without any content, and scrape them. Then make a service that looks for url objects with content but that is missing ML-filled in details, and have it fill those in. It's pretty good for disparate teams with different sets of technology. One group doing document classification, another trying NLP, another using RNNs, etc. There are a few times in my career where rethinkdb would have been a killer feature, especially with it's well-documented language bindings.

jasondc 9y ago

Definitely valuable, as an aside, changefeeds are now in mongodb too: https://emptysqua.re/blog/driver-features-for-mongodb-3-6/#change-streams https://emptysqua.re/blog/driver-features-for-mongodb-3-6/#c...

traverseda 9y ago
and postgres!
- Deimorz 9y ago
  Do you mean using LISTEN/NOTIFY, or some other method?
  - williamstein 9y ago
    Probably LISTEN/NOTIFY. I explain in detail how I migrated from RethinkDB to PostgreSQL using LISTEN/NOTIFY + tons of additional work here http://blog.sagemath.com/2017/02/09/rethinkdb-vs-postgres.html http://blog.sagemath.com/2017/02/09/rethinkdb-vs-postgres.ht... I've continued working on this codebase, even pushing commits this week like this one: https://github.com/sagemathinc/cocalc/commit/c20a62446b6e43cd56300d6f07808c76fd2d239b https://github.com/sagemathinc/cocalc/commit/c20a62446b6e43c...
    - Deimorz 9y ago
      Haha, I actually just finished skimming through that exact blog post because it was one of the first things that came up when I searched for "postgresql changefeed" to see if there was some other functionality for doing it that I didn't know about. I'll definitely need to go back and read it more thoroughly later and take a look through your code, thanks for the links.
  - chillydawg 9y ago
    You could do it with pglogical, if you're feeling particularly adventurous.

traverseda 9y ago

Games and chat are always popular examples, but I think it's really valuable for data-science. You can also "fill in" missing data. If you were writing a webscraper, you could make a service that looks for url objects without any content, and scrape them. Then make a service that looks for url objects with content but that is missing ML-filled in details, and have it fill those in. It's pretty good for disparate teams with different sets of technology. One group doing document classification, another trying NLP, another using RNNs, etc. There are a few times in my career where rethinkdb would have been a killer feature, especially with it's well-documented language bindings.