I did a lot of tinkering around recently to get an advanced query working for me which ended up being quite tricky to work through. I have Project pages (eg [[12335]] ) and on journal pages I have job note blocks for specific jobs ie #12335 Notes with a :job property so the block title can change if needed. There are multiple levels of notes / subnotes / tasks here and I was attempting to do the below query before I learned or-join, but the query was fragile & failing if tasks weren’t at a specific indent level. I ended up spending a Sunday afternoon deep diving into this stuff to figure this out.

• As I understand it, the datomic data model is just a HUUGE list of ‘datoms’ which are super basic [element-id|attribute|value] rows for everything.
• There is some concept of ‘unifying’ which is a variable that appears twice in a :where represents the same value across all clauses.
• Something like (or-join) allows you to control this unification to selected sub items.
  • My visualization on the query is a graph of conditions
  • The :find (?task) element is absolutely required
  • There are ‘facts’ you want to satisfy [(get ?prop :job) ?job] [(contains? #{"TODO" "WAITING" "DOING"} ?marker)].
  • ?task → ?prop (through or-join) → ?prop must contain :job with value :current-page
  • . ↳ ?marker -> must be one of TODO / WAITING / DOING

#+BEGIN_QUERY
{
  :title [:h3 "📅 Outstanding Tasks"]
  :inputs [:current-page]
  :query [
    :find (pull ?task [*])
    :in $ ?job
    :where
      (or-join [?task ?prop]        ; only care that ?task and ?prop are 'unified' with rest of clauses
       (and
        [?task :block/page ?page]
        [?page :block/properties-text-values ?prop]    ; does page have :job property?
        )
       (and
        [?task :block/parent ?tp]
        [?tp :block/properties-text-values ?prop]    ; does task parent have :job property?
        )
       (and
        [?task :block/parent ?tp]
        [?tp :block/parent ?tpp]
        [?tpp :block/properties-text-values ?prop]    ; does task grand-parent contain :job prop?
        )
       (and
        [?task :block/parent ?tp]
        [?tp :block/parent ?tpp]
        [?tpp :block/parent ?tppp]
        [?tppp :block/properties-text-values ?prop]    ; does task great-grand-parent contain :job prop?
        )
      )
      [(get ?prop :job) ?job]                           ; does one-of ?props from above contain :job <%current page%>?
      [?task :block/marker ?marker]                                   
      [(contains? #{"TODO" "WAITING" "DOING"} ?marker)]  ; ?task:block/marker must match one of these
  ]
  :table-view? false
  :result-transform (fn [result]
      (sort-by (fn [m]
                (get m :block/marker)) > result
      )
      )
  :breadcrumb-show? false
  :collapsed? false
}
#+END_QUERY