Rollback deletes only tagged events (of tag_view) after the given sequence number #203
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added 4 commits
April 13, 2023 11:15
Since the rollback doesn't execute the tag view full rebuild, which requires all past events, it can support the deletion of past events.
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Closes #202
The new rollback deletes only tagged events after the given sequence number. Since the new rollback doesn't execute the full rebuild of
tag_views, which requires all old events, it can support the deletion of old events.Related components of Akka Persistence Cassandra
The related classes are the following:
CassandraJournal: https://github.com/akka/akka-persistence-cassandra/blob/v1.0.5/core/src/main/scala/akka/persistence/cassandra/journal/CassandraJournal.scalaTagWriters: https://github.com/akka/akka-persistence-cassandra/blob/v1.0.5/core/src/main/scala/akka/persistence/cassandra/journal/TagWriters.scalaTagWriter: https://github.com/akka/akka-persistence-cassandra/blob/v1.0.5/core/src/main/scala/akka/persistence/cassandra/journal/TagWriter.scalaCassandraTagRecovery: https://github.com/akka/akka-persistence-cassandra/blob/v1.0.5/core/src/main/scala/akka/persistence/cassandra/journal/CassandraTagRecovery.scalaThere are two tables (
tag_write_progress,tag_scanning) that track metadata fortag_viewstable.tag_write_progresstracks the last tagged events information that a tag writer successfully wrote intotag_view.tag_write_progresstracks the progress per the combination of persistence ID and tag.tag_scanningtracks the first event info that the actor should scan at its start, which is not used for an event replay but used for a tag recovery. The tag recovery scans events and then writes events (if the event has a tag) totag_viewsvia a tag writer. The tag recovery is needed if tagged event writing is behind the event replay.