trait EventsByTagQuery extends ReadJournal
A plugin may optionally support this query by implementing this interface.
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- EventsByTagQuery.scala
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Abstract Value Members
- abstract def eventsByTag(tag: String, offset: Offset): Source[EventEnvelope, NotUsed]
Query events that have a specific tag.
Query events that have a specific tag. A tag can for example correspond to an aggregate root type (in DDD terminology).
The consumer can keep track of its current position in the event stream by storing the
offset
and restart the query from a givenoffset
after a crash/restart.The exact meaning of the
offset
depends 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
offset
is 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
offset
if 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 CurrentEventsByTagQuery#currentEventsByTag.
Concrete Value Members
- final def !=(arg0: Any): Boolean
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- def +(other: String): String
- Implicit
- This member is added by an implicit conversion from EventsByTagQuery toany2stringadd[EventsByTagQuery] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
- def ->[B](y: B): (EventsByTagQuery, B)
- Implicit
- This member is added by an implicit conversion from EventsByTagQuery toArrowAssoc[EventsByTagQuery] performed by method ArrowAssoc in scala.Predef.
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- @throws(classOf[java.lang.CloneNotSupportedException]) @HotSpotIntrinsicCandidate() @native()
- def ensuring(cond: (EventsByTagQuery) => Boolean, msg: => Any): EventsByTagQuery
- Implicit
- This member is added by an implicit conversion from EventsByTagQuery toEnsuring[EventsByTagQuery] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: (EventsByTagQuery) => Boolean): EventsByTagQuery
- Implicit
- This member is added by an implicit conversion from EventsByTagQuery toEnsuring[EventsByTagQuery] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean, msg: => Any): EventsByTagQuery
- Implicit
- This member is added by an implicit conversion from EventsByTagQuery toEnsuring[EventsByTagQuery] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean): EventsByTagQuery
- Implicit
- This member is added by an implicit conversion from EventsByTagQuery toEnsuring[EventsByTagQuery] performed by method Ensuring in scala.Predef.
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- Ensuring
- final def eq(arg0: AnyRef): Boolean
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- Deprecated
(Since version 9)
- def formatted(fmtstr: String): String
- Implicit
- This member is added by an implicit conversion from EventsByTagQuery toStringFormat[EventsByTagQuery] performed by method StringFormat in scala.Predef.
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- StringFormat
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- @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,formatted
resolves to the new method in String which has reversed parameters.
- def →[B](y: B): (EventsByTagQuery, B)
- Implicit
- This member is added by an implicit conversion from EventsByTagQuery toArrowAssoc[EventsByTagQuery] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
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- @deprecated
- Deprecated
(Since version 2.13.0) Use
->
instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.