Hello. Fairly new to datomic. I'm attempting to write a query that returns entities which have had attributes updated since a point in time. I can't figure out why the first two queries work great, but the third one just hangs for 30 seconds and return Server error.

(d/q '[:find (pull ?e [*])
       :in $all $new
       :where
       [$all ?e :customer/id]
       [$new ?e :customer/first-name]]
     db
     (d/since db t))

(d/q '[:find (pull ?e [*])
       :in $all $new
       :where
       [$all ?e :customer/id]
       [$new ?e :customer/last-name]]
     db
     (d/since db t))

(d/q '[:find (pull ?e [*])
       :in $all $new
       :where
       [$all ?e :customer/id]
       (or [$new ?e :customer/first-name]
           [$new ?e :customer/last-name])]
     db
     (d/since db t))

@skuttleman I wonder if the or clause can only target one src-var. Did you try to put the $new before the or clause? I never encountered this case. Does it mean you cannot write a or clause across src-vars?

For this kind of historical queries I would use the log API and check for the attributes I'm interested in in each transaction since t.

@me1740 @marshall Thanks for responding. I ended up getting it to work last night after finding this: https://docs.datomic.com/on-prem/query.html#how-or-clauses-work The or clause can only target one src-var

(d/q '[:find (pull ?e [*])
       :in $all $new
       :where
       [$all ?e :customer/id]
       ($new or
             [?e :customer/first-name]
             [?e :customer/last-name])]
     db
     (d/since db t))

@skuttleman Ok, that's it. Thanks for the relevant link to the docs.

In datomic ions, where would I put something I might normally do in a component/integrant system? e.g. create a postgresql hikari connection pool (yes, yes I know, but this is a clear example).

I'm using Mount in ions. The only thing that is mildly special is that I have some code in the root of a namespace which checks the environment. If the environment is not the desktop (ie, either :dev or :prod), it mounts the system

How does code check the environment?

@dominicm https://docs.datomic.com/cloud/ions/ions-reference.html#parameters

How do parameters work in development?

Does datomic support a sort aggregate?

Generally no, if you mean something similar to SQL's ORDER BY. In the peer model you'll typically do the sorting in your application code.

I am running an Ion using the client model