hi guys, is there anyway we can output missing fact as nil in datomic query ? Thanks

@nxqd: Datomic has no concept of a "missing fact", so there is no direct way to include keys in entities that are not present with a value. You need to be aware that any entity can have any attribute attached. There are not "entity types" which would restrict the possible attributes to a certain set.

@nxqd: What this means is that Datomic can't do it for you, but you can certainly do it yourself in your data layer which sits between your application and datomic.

@nxqd: I've used a similar query to this (not with nil in my case). Maybe it will work:

(or (and [(missing? $ ?entity :some/attribute)]
         [(identity nil) ?value])
    [?entity :some/attribute ?value])

@nxqd: Also, there's get-else (http://docs.datomic.com/query.html#get-else) and pull default expressions (http://docs.datomic.com/pull.html#default-expressions)

I've always had the impression that the rest api service counts as a normal licensed peer - is this correct?

@ckarlsen Yes, the REST API is a peer.

for some reason I can run 2 jvm peers + 1 rest service with a 2 peer license...

usually the third peer just throws an exception on connect

Is it possible to use a lookup ref instead of entity id in :db.fn/cas? Or even better, a temporary id (negative) in the same transaction that asserts a :unique/identity attribute and the :db/id? Also, what if entity has two identity attributes in the same transaction, one matches and the other doesn't? Does it resolve entity ID by the first one in the transaction sequence?

@yonatanel cool, those seem to be what I need.