@adammiller correct. we're going to deploy the on-prem version on an ec2 instances backed by postgres, using the datomic-pro maven library bundled with the download. it turns out so much of our code had (datoms ...) and other peer-only features

or is it (entitiy ...) instead of datoms, some functions are only avilable on the peer server

Yeah, api is just slightly different in certain situations.

so in dev we use mount (its like sierra's component) to start datomic in memory peer, and run our tests etc, knowing it will work in production (but we are stil amateurs!! 😼 )

the other advantage of using on-prem version is that we can start postgres on our laptops and run the full version with tests, etc

Yes, I'm also using mount and I determine by the config currently whether to launch a peer or client connection then use Robert's method basically to wrap the api between client and peer api methods (https://github.com/robert-stuttaford/bridge/blob/master/src/bridge/data/datomic.clj)

i like robert's approach; it's a nice first try of bridging the gap

i would have used a multimethod or so

but still would be scared of breaking things deep inside the AWS cloudformation stack

problem with multi-method i believe is you would have to pass the mode around (at least if you were thinking of dispatching on that). His method works nice using the with-datomic-mode macro to bind what mode we are working in.

None of this would be needed if we could launch an in memory db from code so that we could connect with the client but I don't believe that is possible.

Would be amazing if datomic-free supported the client api

How would i approach the abstract problem of walking a graph from leaf to root(s) with datomic. Is it even a good fit for this type of question? I understand its a graph db, but its not clear how well the semantics support this type of thing.

say n1 -> n2 -> n3 and also n1 -> n4 and just for contrast n5 -> n6 if i handed this thing n1 it would return n1 -> n2 -> n3 and n1 -> n4 but not n5 -> n6

i think component pulls nested components so thats one way to think about tackling this.

So, this is off the top of my head pseudocode but you would navigate the “edges” that are ref values from one entity to the other

I won’t try to come up with a schema on the fly, but your query would look something like

hm, wait - sorry, I misread your question and was about to answer a different one 🙂

specifically, “how do I walk from root to leaf of a structure I know”, where I now think you’re asking “how do I find all the leaves and paths to them from a given root without knowledge of the structure beforehand”

@adammiller no problem. Once I’ve tested it in my codebase, I’ll be happy to extract a micro-library.

The first link on this page is wrong https://docs.datomic.com/cloud/time/log.html