Package org.apache.pekko.persistence.query.scaladsl

Interface DurableStateStoreQuery<A>

    • Method Detail

      • changes

        Source<DurableStateChange<A>,​NotUsed> changes​(java.lang.String tag,
                                                    Offset offset)
        Get a source of the most recent changes made to objects of the given tag since the passed in offset.

        The returned source will never terminate, it effectively watches for changes to the objects and emits changes as they happen.

        Not all changes that occur are guaranteed to be emitted, this call only guarantees that eventually, the most recent change for each object since the offset will be emitted. In particular, multiple updates to a given object in quick succession are likely to be skipped, with only the last update resulting in a change from this source.

        The DurableStateChange elements can be pekko.persistence.query.UpdatedDurableState or pekko.persistence.query.DeletedDurableState.

        Parameters:
        tag - The tag to get changes for.
        offset - The offset to get changes since. Must either be pekko.persistence.query.NoOffset to get changes since the beginning of time, or an offset that has been previously returned by this query. Any other offsets are invalid.
        Returns:
        A source of change in state.

      • currentChanges

        Source<DurableStateChange<A>,​NotUsed> currentChanges​(java.lang.String tag,
                                                           Offset offset)
        Get a source of the most recent changes made to objects with the given tag since the passed in offset.

        Note that this only returns the most recent change to each object, if an object has been updated multiple times since the offset, only the most recent of those changes will be part of the stream.

        This will return changes that occurred up to when the Source returned by this call is materialized. Changes to objects made since materialization are not guaranteed to be included in the results.

        The DurableStateChange elements can be pekko.persistence.query.UpdatedDurableState or pekko.persistence.query.DeletedDurableState.

        Parameters:
        tag - The tag to get changes for.
        offset - The offset to get changes since. Must either be pekko.persistence.query.NoOffset to get changes since the beginning of time, or an offset that has been previously returned by this query. Any other offsets are invalid.
        Returns:
        A source of change in state.