Journal plugin

The journal plugin enables storing and loading events for event sourced persistent actors.


The event_journal table and event_journal_slice_idx index need to be created in the configured database, see schema definition in Creating the schema.

The event_journal_slice_idx index is only needed if the slice based queries are used.


To enable the journal plugin to be used by default, add the following line to your Akka application.conf:

akka.persistence.journal.plugin = "akka.persistence.r2dbc.journal"

It can also be enabled with the journalPluginId for a specific EventSourcedBehavior and multiple plugin configurations are supported.

See also Connection configuration.

Reference configuration

The following can be overridden in your application.conf for the journal specific settings:

sourceakka.persistence.r2dbc {
  journal {
    class = "akka.persistence.r2dbc.journal.R2dbcJournal"

    # name of the table to use for events
    table = "event_journal"

    # Otherwise it would be a pinned dispatcher, see
    plugin-dispatcher = ""

    # event replay is using akka.persistence.r2dbc.query.buffer-size

    # Enable this to reduce latency of eventsBySlices. The persisted events will be
    # published as Akka messages and consumed directly by running eventsBySlices
    # queries. Tradeoff is more CPU and network resources that are used. The events
    # must still be retrieved from the database, but at a lower polling frequency,
    # because delivery of published messages are not guaranteed.
    publish-events = off

    # replay filter not needed for this plugin
    replay-filter.mode = off


The journal supports deletes through hard deletes, which means the journal entries are actually deleted from the database. There is no materialized view with a copy of the event so make sure to not delete events too early if they are used from projections or queries.

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