A couple of or-join examples against a toy schema.

or_join.clj

(ns datomic-manual-tests.or-join
  (:require [datomic.api :as d]))

(def db-uri (apply str ["datomic:mem://test" (d/squuid)]))
(d/create-database db-uri)
(def conn (d/connect db-uri))

(def schema
 [{:db/id (d/tempid :db.part/db)
   :db/ident :person/name
   :db/valueType :db.type/string
   :db/cardinality :db.cardinality/one
   :db/unique :db.unique/identity
   :db.install/_attribute :db.part/db}
  {:db/id (d/tempid :db.part/db)
   :db/ident :person/active
   :db/valueType :db.type/boolean
   :db/cardinality :db.cardinality/one
   :db.install/_attribute :db.part/db}
  {:db/id (d/tempid :db.part/db)
   :db/ident :person/vip
   :db/valueType :db.type/boolean
   :db/cardinality :db.cardinality/one
   :db.install/_attribute :db.part/db}
  {:db/id (d/tempid :db.part/db)
   :db/ident :org/contact
   :db/valueType :db.type/ref
   :db/cardinality :db.cardinality/one
   :db.install/_attribute :db.part/db}
  {:db/id (d/tempid :db.part/db)
   :db/ident :org/name
   :db/valueType :db.type/string
   :db/cardinality :db.cardinality/one
   :db.install/_attribute :db.part/db}])

@(d/transact conn schema)

(def tx [{:db/id (d/tempid :db.part/user)
          :person/name "Jim"
          :person/vip false
          :person/active true}
         {:db/id (d/tempid :db.part/user)
          :person/name "Joan"
          :person/vip true
          :person/active true}
         {:db/id (d/tempid :db.part/user)
          :person/name "Bob"
          :person/vip false
          :person/active false}
         {:db/id (d/tempid :db.part/user)
          :person/name "Ben"
          :person/vip true
          :person/active false}])

@(d/transact conn tx)

(def orgs-tx [{:db/id (d/tempid :db.part/user)
               :org/name "Synergy Corp"
               :org/contact [:person/name "Ben"]}
              {:db/id (d/tempid :db.part/user)
               :org/name "Our Astounding Journey"
               :org/contact [:person/name "Bob"]}
              {:db/id (d/tempid :db.part/user)
               :org/name "Active 500 Corp"
               :org/contact [:person/name "Joan"]}
              {:db/id (d/tempid :db.part/user)
               :org/name "Bootstrap Startup, Inc."
               :org/contact [:person/name "Jim"]}])

@(d/transact conn orgs-tx)


; Straight forward case of getting active or vip user.
(d/q '[:find (pull ?p [*])
       :where [?p :person/name]
              (or-join [?p]
                       [?p :person/vip true]
                       [?p :person/active true])]
     (d/db conn))

; Less straight forward case of getting org w/active or vip user
(d/q '[:find [(pull ?o [:org/name]) ...]
       :where [?o :org/contact ?p]
              (or-join [?p]
                       [?p :person/vip true]
                       [?p :person/active true])]
     (d/db conn))
; Returns [{:org/name "Synergy Corp"} {:org/name "Active 500 Corp"} {:org/name "Bootstrap Startup, Inc."}]