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datomic 2026-03-19
What is the most idiomatic way to write a query that joins two entities and returns them in one "bucket"? For example, let's say I want to return all nodes in a tree that match some criterion, and their parents:
[:find [?node ...]
:in $ ?type
:where
[?node :node/type ?type]
[?node :node/parent ?parent]]?node and ?parent values, ideally in a single collection. Can I do this with a subquery? With or ?
I've used rules with multiple inputs for this. Easy-peasy.
i believe this is a pull
i'm on my phone or i'd pull up the docs for you
I want a set of entity ids, not maps. I don't think you can do this with pull.
👍 1
(of course I could get the maps and pull out the entity IDs after ... but I'm wondering if there is some way to do this directly in the query.)
jumraiya 2026-03-19T23:11:44.321889Z
Maybe a recursive rule?
favila 2026-03-19T23:18:39.756599Z
Or
favila 2026-03-19T23:18:59.010999Z
(Or rule with multiple impls)
braai engineer 2026-03-29T21:53:50.812399Z
@enn d/index-range against heterogeneous tuple :node/type+parent – essentially an index on type + parent.
Are you only looking for immediate descendants of that specific parent, or a recursive tree? d/pull can do recursive queries as Noah said.