Same type of query as eventsByPersistenceId but the event stream is completed immediately when it reaches the end of the "result set". Events that are stored after the query is completed are not included in the event stream.

Same type of query as eventsByTag but the event stream is completed immediately when it reaches the end of the "result set". Events that are stored after the query is completed are not included in the event stream.

Same type of query as persistenceIds but the event stream is completed immediately when it reaches the end of the "result set". Events that are stored after the query is completed are not included in the event stream.

eventsByPersistenceId is used to retrieve a stream of events for a particular persistenceId.

The EventEnvelope contains the event and provides persistenceId and sequenceNr for each event. The sequenceNr is the sequence number for the persistent actor with the persistenceId that persisted the event. The persistenceId + sequenceNr is an unique identifier for the event.

fromSequenceNr and toSequenceNr can be specified to limit the set of returned events. The fromSequenceNr and toSequenceNr are inclusive.

The EventEnvelope also provides the offset that corresponds to the ordering column in the Journal table. The ordering is a sequential id number that uniquely identifies the position of each event, also across different persistenceId. The Offset type is akka.persistence.query.Sequence with the ordering as the offset value. This is the same ordering number as is used in the offset of the eventsByTag query.

The returned event stream is ordered by sequenceNr.

Causality is guaranteed (sequenceNrs of events for a particular persistenceId are always ordered in a sequence monotonically increasing by one). Multiple executions of the same bounded stream are guaranteed to emit exactly the same stream of events.

The stream is not completed when it reaches the end of the currently stored events, but it continues to push new events when new events are persisted. Corresponding query that is completed when it reaches the end of the currently stored events is provided by currentEventsByPersistenceId.

Query events that have a specific tag.

The consumer can keep track of its current position in the event stream by storing the offset and restart the query from a given offset after a crash/restart. The offset is exclusive, i.e. the event corresponding to the given offset parameter is not included in the stream.

For akka-persistence-jdbc the offset corresponds to the ordering column in the Journal table. The ordering is a sequential id number that uniquely identifies the position of each event within the event stream. The Offset type is akka.persistence.query.Sequence with the ordering as the offset value.

The returned event stream is ordered by offset.

The stream is not completed when it reaches the end of the currently stored events, but it continues to push new events when new events are persisted. Corresponding query that is completed when it reaches the end of the currently stored events is provided by CurrentEventsByTagQuery#currentEventsByTag.

persistenceIds is used to retrieve a stream of all persistenceIds as strings.

The stream guarantees that a persistenceId is only emitted once and there are no duplicates. Order is not defined. Multiple executions of the same stream (even bounded) may emit different sequence of persistenceIds.

The stream is not completed when it reaches the end of the currently known persistenceIds, but it continues to push new persistenceIds when new events are persisted. Corresponding query that is completed when it reaches the end of the currently known persistenceIds is provided by currentPersistenceIds.