History#

VevDB provides immutable historical database values over the same datom model.

Operation	Boundary	Result
`as-of`	inclusive	state through a point in time
`since`	exclusive	current assertions added after a point in time
`history`	none	assertions and retractions

A time point can be a basis t, transaction entity ID, or instant.

(def current (d/db conn))
(def earlier (d/as-of current t))
(def recent (d/since current t))
(def audit (d/history current))

These functions return immutable database values. They do not change the connection or source value.

Five-position data clauses expose transaction and assertion state:

(d/q '[:find ?value ?tx ?added
       :where
       [?e :person/name ?value ?tx ?added]]
     audit)

Database metadata#

(d/basis-t db)
(d/next-t db)
(d/as-of-t earlier)
(d/since-t recent)
(d/history? audit)

basis-t is the basis of the source database. as-of-t and since-t report the filter boundary.

Convert between basis values and transaction entity IDs with t->tx and tx->t.

(d/tx-range (d/log conn) start end)

The start is inclusive. The end is exclusive. Either bound may be nil. Results have {:t t :data datoms} shape.

Durable stores keep history across close and reopen.

Run the Datomic comparison:

scripts/compare_history_time_filters.sh