Hey, I've been looking at this with @UNDH5EQRL in the last few days. The likely solution is a crux-hook-tx module that provides the raw feed of transactions, so you would need to filter these to determine new/changed/deleted/evicted entities vs retroactive/proactive ops. We would publish it to crux-labs for the moment.

It would use crux.bus under the hood, something like this:

(ns crux.hook.tx
  (:require [crux.api :as api]
            [crux.bus :as bus]))

(defn event-stream [{:crux.node/keys [bus]} args]
  (bus/listen bus {:crux.bus/event-types #{:crux.tx/indexed-tx}}
              (fn [event] (tap> event))))

(def module {::event-stream {:start-fn #'crux.hook.tx/event-stream
                             :deps #{:crux.node/bus}}})

(def node (api/start-node {:crux.node/topology ['crux.standalone/topology
                                                'crux.hook.tx/module]
                           :crux.node/kv-store "crux.kv.memdb/kv"
                           :crux.kv/db-dir "data/db-dir-1"
                           :crux.standalone/event-log-dir "data/eventlog-1"
                           :crux.standalone/event-log-kv-store "crux.kv.memdb/kv"}))

I was planning to look into it again in the next couple of days and move it forward (it needs a way to register/unregister cb listeners, also the new event type needs merging into tx.clj)

Sorry, I meant to ask if there is a thing like (api/db-after node my-valid-time my-tx-time) Like a reverse of api/db which gives the db as it was before a given moment in time

But hooks are awesome news!

Ah okay, I was thrown off by the word "receive" I think 🙂 I'm not sure I understand how your db-after should work. It sounds like you want to invert the valid-time axis entirely so that your db value can only access things that are in the future (which could modelled as the past in a parallel crux instance where valid-time is inverted). Maybe an example would help?

Also, at the risk of being pedantic, I'm pretty certain db currently gives the db at a moment in time, not before :thinking_face:

I meant to ask if there’s a way to see all facts occurred after a moment in valid time. Sure, I can do this on the application level. Asking in case if there is a new temporal index or something.

I can't think how to do anything like that with the current indexes. We don't have immediate plans for any new indexes although we do have an R&D track... Perhaps you can also maintain your own reified transaction index alongside your data with a transaction function

Again I think a worked example might help inspire solutions

@U0A5V8ZR6: you can already get the tx-log from a particular tx-id - would https://opencrux.com/docs#_tx_log work for your use case?

failing that, history-ascending on a DB value would get you all of the versions of a given entity from that DB forward (i.e. fixed tx-time, ascending valid-time)

@U050V1N74 @taylor.jeremydavid thanks for the input! ❤️ I’ll stick to app level implementation then, as all I need is basically just a date comparison like

{:find [e]
 :where 
  [[e :create-time ct]
   [(> ct #inst "2020-02-10")]]}

np 🙂 fwiw, we're also considering how we can efficiently implement that kind of query - there are a few cards in our roadmap along these lines: https://github.com/juxt/crux/projects/8#column-7117153

Yes, it is