Just got started again on my "Poor Man's Bitemporal Data System" (discussed here: https://news.ycombinator.com/item?id=45118585 ).

Holidays nuked all the hot-cached context in my head. I spent a few days just spinning wheels until it repopulated. But the basic idea works now!

Much testing and benchmarking work remains to make sure it's not going to lose data, and that it won't denial-of-service itself (because object-map -> facts fan-out is big).

Also a second giant blog post is due (following the one discussed above). Lots of notes have accumulated.

It will be fun even if the concept ultimately crashes and burns to the ground :)

In which case, there's always datomic and xtdb :D

  (def repl-facts
    [{:alt.site.evalapply/meta
      {:description "Root namespace for a named site."}}
     {:alt.site.evalapply/features
      {:paid #{:alt.site-feature/feat-1
               :alt.site-feature/feat-2
               :alt.site-feature/feat-3}
       :trial #{:alt.site-feature/feat-4}
       :complimentary #{}
       :available #{}}}
     {:alt.site.evalapply/users
      {:authorised #{:alt.user.evalapply/user-1
                     :alt.user.evalapply/user-2
                     :alt.user.evalapply/user-3}
       :unauthorized #{:alt.root.*}}
      :alt.user.evalapply/user-1 {:name {:first "Wiley"
                                         :last "Coyote"}
                                  :roles #{:alt.role.evalapply/owner}}
      :alt.role.evalapply/owner {:rw #{:alt.user.evalapply/*}
                                 :ro #{}}}])

  (assert-facts! (#'user/system-state)
                 ::app
                 :alt.root/user-1
                 (uuid/v7)
                 repl-facts)

  (redact-facts! (#'user/system-state)
                 ::app
                 :alt.root/user-1
                 (uuid/v7)
                 (subvec repl-facts 2))

  (read-now! (#'user/system-state)
             ::app)

Love the idea! Read only the beginning of the first "giant blog post" so maybe it's discussed there, but in Sqlite doesn't WAL mode give you a kind of super simple, super basic temporal data system? If you somehow kept all WAL entries 'as is', it should be possible to reconstruct the state of the db at any point in the past?