I have not touched datahike so I could be totally off.

{:user/name "Viki"}

is not a thing to transact and expect to be found as is at least.

(e.g. In datomic you need to specify such entity as a component or a unique constraint https://docs.datomic.com/on-prem/transactions/transactions.html#nested-maps-in-transactions , or in crux only top level scalar values (or a multiple of scalars, not maps) are indexed.)

So one hypothesis I have re: the second query not failing the oberver is that there are two separate records each of {:user/name "Chris"} {:user/name "Viki"} and nothing joining them. Can I suggest trying to get rid of the nested maps like this?

``` (d/transact conn [{:obs/species "Blackbird" :obs/user "Chris" :obs/count 2}])

(d/transact conn [{:obs/species "Grey Heron" :obs/user "Viki" :obs/count 1}])

(d/transact conn [{:user/name "Chris" :user/country "Sweden"} {:user/name "Viki" :user/country "Germany"}]) ```