Datomic datalog: ArrayIndexOutOfBounds Exception when using aggregates - exception

Question

Given that db is a database value, the following query throws an exception:
(d/q
'[:find ?concert (count-distinct ?demand)
:in $ ?campaignId
:with ?concert
:where
[?c :campaign/id ?campaignId]
[?concert :crowd-concert/campaign ?c]
[?demand :demand/concert ?concert]
]
db "546b7e0f2348f10200abf5ea")
(The information model is that there are several concerts belonging to a campaign, and demands that , and we want to fetch the concert fields and the number of demands for each concert).
The stacktrace is here:
java.lang.Exception: processing rule: (q__25764 ?concert ?demand ?concert), message: processing clause: [?demand :demand/concert ?concert], message: java.lang.ArrayIndexOutOfBoundsException: 2
at datomic.datalog$eval_rule$fn__6161.invoke(datalog.clj:1441)
at datomic.datalog$eval_rule.invoke(datalog.clj:1421)
at datomic.datalog$eval_query.invoke(datalog.clj:1464)
at datomic.datalog$qsqr.invoke(datalog.clj:1553)
at datomic.datalog$qsqr.invoke(datalog.clj:1510)
at datomic.query$q.invoke(query.clj:674)
at datomic.api$q.doInvoke(api.clj:35)
at clojure.lang.RestFn.invoke(RestFn.java:439)
at bs.routes.campaigns$eval25762.invoke(NO_SOURCE_FILE:1)
at clojure.lang.Compiler.eval(Compiler.java:6782)
at clojure.lang.Compiler.eval(Compiler.java:6745)
at clojure.core$eval.invoke(core.clj:3081)
at clojure.main$repl$read_eval_print__7099$fn__7102.invoke(main.clj:240)
at clojure.main$repl$read_eval_print__7099.invoke(main.clj:240)
at clojure.main$repl$fn__7108.invoke(main.clj:258)
at clojure.main$repl.doInvoke(main.clj:258)
at clojure.lang.RestFn.invoke(RestFn.java:1523)
at clojure.tools.nrepl.middleware.interruptible_eval$evaluate$fn__1025.invoke(interruptible_eval.clj:53)
at clojure.lang.AFn.applyToHelper(AFn.java:152)
at clojure.lang.AFn.applyTo(AFn.java:144)
at clojure.core$apply.invoke(core.clj:630)
at clojure.core$with_bindings_STAR_.doInvoke(core.clj:1868)
at clojure.lang.RestFn.invoke(RestFn.java:425)
at clojure.tools.nrepl.middleware.interruptible_eval$evaluate.invoke(interruptible_eval.clj:51)
at clojure.tools.nrepl.middleware.interruptible_eval$interruptible_eval$fn__1067$fn__1070.invoke(interruptible_eval.clj:183)
at clojure.tools.nrepl.middleware.interruptible_eval$run_next$fn__1060.invoke(interruptible_eval.clj:152)
at clojure.lang.AFn.run(AFn.java:22)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.Exception: processing clause: [?demand :demand/concert ?concert], message: java.lang.ArrayIndexOutOfBoundsException: 2
at datomic.datalog$eval_clause$fn__6135.invoke(datalog.clj:1387)
at datomic.datalog$eval_clause.invoke(datalog.clj:1350)
at datomic.datalog$eval_rule$fn__6161.invoke(datalog.clj:1436)
... 29 more
Caused by: java.util.concurrent.ExecutionException: java.lang.ArrayIndexOutOfBoundsException: 2
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at clojure.core$deref_future.invoke(core.clj:2186)
at clojure.core$deref.invoke(core.clj:2207)
at clojure.core$mapv$fn__6727.invoke(core.clj:6616)
at clojure.lang.PersistentVector.reduce(PersistentVector.java:333)
at clojure.core$reduce.invoke(core.clj:6518)
at clojure.core$mapv.invoke(core.clj:6616)
at datomic.datalog$fn__5678.invoke(datalog.clj:588)
at datomic.datalog$fn__5536$G__5508__5551.invoke(datalog.clj:51)
at datomic.datalog$join_project_coll.invoke(datalog.clj:116)
at datomic.datalog$fn__5607.invoke(datalog.clj:219)
at datomic.datalog$fn__5515$G__5510__5530.invoke(datalog.clj:51)
at datomic.datalog$eval_clause$fn__6135.invoke(datalog.clj:1356)
... 31 more
Caused by: java.lang.ArrayIndexOutOfBoundsException: 2
at clojure.lang.RT.aset(RT.java:2326)
at datomic.datalog$fn__5678$project__5749.invoke(datalog.clj:480)
at datomic.datalog$fn__5678$join__5767.invoke(datalog.clj:578)
at datomic.datalog$fn__5678$fn__5772$fn__5773.invoke(datalog.clj:588)
at clojure.lang.AFn.applyToHelper(AFn.java:152)
at clojure.lang.AFn.applyTo(AFn.java:144)
at clojure.core$apply.invoke(core.clj:630)
at clojure.core$with_bindings_STAR_.doInvoke(core.clj:1868)
at clojure.lang.RestFn.invoke(RestFn.java:425)
at clojure.lang.AFn.applyToHelper(AFn.java:156)
at clojure.lang.RestFn.applyTo(RestFn.java:132)
at clojure.core$apply.invoke(core.clj:634)
at clojure.core$bound_fn_STAR_$fn__4439.doInvoke(core.clj:1890)
at clojure.lang.RestFn.invoke(RestFn.java:397)
at clojure.lang.AFn.call(AFn.java:18)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
... 3 more
Am I doing something wrong ?

Answer 1

Removing the :with clause solved the problem.
I don't know Datalog enough to know why exactly, but I assume that's because there's some redundancy in ?concert being in both :find and :with clauses.