akka.persistence.query.typed.javadsl
EventsBySliceFirehoseQuery
Companion object EventsBySliceFirehoseQuery
final class EventsBySliceFirehoseQuery extends ReadJournal with EventsBySliceQuery with EventsBySliceStartingFromSnapshotsQuery with EventTimestampQuery with LoadEventQuery
This wrapper of EventsBySliceQuery gives better scalability when many consumers retrieve the same events, for example many Projections of the same entity type. The purpose is to share the stream of events from the database and fan out to connected consumer streams. Thereby fewer queries and loading of events from the database.
It is retrieved with:
EventsBySliceQuery queries =
PersistenceQuery.get(system).getReadJournalFor(EventsBySliceQuery.class, EventsBySliceFirehoseQuery.Identifier());Corresponding Scala API is in akka.persistence.query.typed.scaladsl.EventsBySliceFirehoseQuery.
Configuration settings can be defined in the configuration section with the
absolute path corresponding to the identifier, which is "akka.persistence.query.events-by-slice-firehose"
for the default EventsBySliceFirehoseQuery#Identifier. See reference.conf.
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- EventsBySliceFirehoseQuery
- LoadEventQuery
- EventTimestampQuery
- EventsBySliceStartingFromSnapshotsQuery
- EventsBySliceQuery
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Instance Constructors
- new EventsBySliceFirehoseQuery(delegate: scaladsl.EventsBySliceFirehoseQuery)
Value Members
- final def !=(arg0: Any): Boolean
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- final def ##: Int
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- def +(other: String): String
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- This member is added by an implicit conversion from EventsBySliceFirehoseQuery toany2stringadd[EventsBySliceFirehoseQuery] performed by method any2stringadd in scala.Predef.
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- any2stringadd
- def ->[B](y: B): (EventsBySliceFirehoseQuery, B)
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- This member is added by an implicit conversion from EventsBySliceFirehoseQuery toArrowAssoc[EventsBySliceFirehoseQuery] performed by method ArrowAssoc in scala.Predef.
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- @throws(classOf[java.lang.CloneNotSupportedException]) @HotSpotIntrinsicCandidate() @native()
- def ensuring(cond: (EventsBySliceFirehoseQuery) => Boolean, msg: => Any): EventsBySliceFirehoseQuery
- Implicit
- This member is added by an implicit conversion from EventsBySliceFirehoseQuery toEnsuring[EventsBySliceFirehoseQuery] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: (EventsBySliceFirehoseQuery) => Boolean): EventsBySliceFirehoseQuery
- Implicit
- This member is added by an implicit conversion from EventsBySliceFirehoseQuery toEnsuring[EventsBySliceFirehoseQuery] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean, msg: => Any): EventsBySliceFirehoseQuery
- Implicit
- This member is added by an implicit conversion from EventsBySliceFirehoseQuery toEnsuring[EventsBySliceFirehoseQuery] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean): EventsBySliceFirehoseQuery
- Implicit
- This member is added by an implicit conversion from EventsBySliceFirehoseQuery toEnsuring[EventsBySliceFirehoseQuery] performed by method Ensuring in scala.Predef.
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- final def eq(arg0: AnyRef): Boolean
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- def equals(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef → Any
- def eventsBySlices[Event](entityType: String, minSlice: Int, maxSlice: Int, offset: Offset): Source[EventEnvelope[Event], NotUsed]
Query events for given slices.
Query events for given slices. A slice is deterministically defined based on the persistence id. The purpose is to evenly distribute all persistence ids over the slices.
The consumer can keep track of its current position in the event stream by storing the
offsetand restart the query from a givenoffsetafter a crash/restart.The exact meaning of the
offsetdepends on the journal and must be documented by the read journal plugin. It may be a sequential id number that uniquely identifies the position of each event within the event stream. Distributed data stores cannot easily support those semantics and they may use a weaker meaning. For example it may be a timestamp (taken when the event was created or stored). Timestamps are not unique and not strictly ordered, since clocks on different machines may not be synchronized.In strongly consistent stores, where the
offsetis unique and strictly ordered, the stream should start from the next event after theoffset. Otherwise, the read journal should ensure that between an invocation that returned an event with the givenoffset, and this invocation, no events are missed. Depending on the journal implementation, this may mean that this invocation will return events that were already returned by the previous invocation, including the event with the passed inoffset.The returned event stream should be ordered by
offsetif possible, but this can also be difficult to fulfill for a distributed data store. The order must be documented by the read journal plugin.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 CurrentEventsBySliceQuery.currentEventsBySlices.
- Definition Classes
- EventsBySliceFirehoseQuery → EventsBySliceQuery
- def eventsBySlicesStartingFromSnapshots[Snapshot, Event](entityType: String, minSlice: Int, maxSlice: Int, offset: Offset, transformSnapshot: Function[Snapshot, Event]): Source[EventEnvelope[Event], NotUsed]
Same as EventsBySliceQuery but with the purpose to use snapshots as starting points and thereby reducing number of events that have to be loaded.
Same as EventsBySliceQuery but with the purpose to use snapshots as starting points and thereby reducing number of events that have to be loaded. This can be useful if the consumer start from zero without any previously processed offset or if it has been disconnected for a long while and its offset is far behind.
- Definition Classes
- EventsBySliceFirehoseQuery → EventsBySliceStartingFromSnapshotsQuery
- final def getClass(): Class[_ <: AnyRef]
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- def hashCode(): Int
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- final def isInstanceOf[T0]: Boolean
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- def loadEnvelope[Event](persistenceId: String, sequenceNr: Long): CompletionStage[EventEnvelope[Event]]
Load a single event on demand.
Load a single event on demand. The
CompletionStageis completed with aNoSuchElementExceptionif the event for the givenpersistenceIdandsequenceNrdoesn't exist.- Definition Classes
- EventsBySliceFirehoseQuery → LoadEventQuery
- final def ne(arg0: AnyRef): Boolean
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- final def notify(): Unit
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- @HotSpotIntrinsicCandidate() @native()
- final def notifyAll(): Unit
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- @HotSpotIntrinsicCandidate() @native()
- def sliceForPersistenceId(persistenceId: String): Int
- Definition Classes
- EventsBySliceFirehoseQuery → EventsBySliceStartingFromSnapshotsQuery → EventsBySliceQuery
- def sliceRanges(numberOfRanges: Int): List[Pair[Integer, Integer]]
- Definition Classes
- EventsBySliceFirehoseQuery → EventsBySliceStartingFromSnapshotsQuery → EventsBySliceQuery
- final def synchronized[T0](arg0: => T0): T0
- Definition Classes
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- def timestampOf(persistenceId: String, sequenceNr: Long): CompletionStage[Optional[Instant]]
- Definition Classes
- EventsBySliceFirehoseQuery → EventTimestampQuery
- def toString(): String
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- final def wait(arg0: Long, arg1: Int): Unit
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- @throws(classOf[java.lang.InterruptedException])
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- Deprecated
(Since version 9)
- def formatted(fmtstr: String): String
- Implicit
- This member is added by an implicit conversion from EventsBySliceFirehoseQuery toStringFormat[EventsBySliceFirehoseQuery] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.12.16) Use
formatString.format(value)instead ofvalue.formatted(formatString), or use thef""string interpolator. In Java 15 and later,formattedresolves to the new method in String which has reversed parameters.
- def →[B](y: B): (EventsBySliceFirehoseQuery, B)
- Implicit
- This member is added by an implicit conversion from EventsBySliceFirehoseQuery toArrowAssoc[EventsBySliceFirehoseQuery] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
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(Since version 2.13.0) Use
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