Slow clean tagged events and overload Cassandra by overfetch insufficient data for deleteFromTagView

[Valocop]

akka-persistence-cassandra/core/src/main/scala/akka/persistence/cassandra/reconciler/DeleteTagViewForPersistenceId.scala

Line 40 in 8006539

.currentEventsByTagInternal(tag, NoOffset)

The problem is that when we try to clean events by tags, Cassandra Journal runs a stream with current events by tag and over fetch data by fetching event payload for every event. It takes a lot of time to clean tag_views.
Better make stream that will be fetch events without payload, these data will be enough for deleteFromTagView.

I faced this problem when cleaning events in tag with a lot of events (millions) and the payload is a big.

Can we fix it, please?
Thanks

[patriknw]

Good point, I'll try to adjust that later this week, unless you want to fix it?

[Valocop]

I would be very grateful for your help!
I can try, but I need to discuss how to implement it.
Better add a new method or change current currentEventsByTagInternal(...) and use flag for fetching all data or without event payload?
@patriknw

Thanks

[patriknw]

I guess, since most things are the same it would be easiest with a flag. In the end it's a different cql (prepared statement) and change in deserializeEventsByTagRow. The payload in the PersistentRepr could be set to NotUsed for this case.

[patriknw]

@Valocop Are you working on this, or shall I give it a try?

[Valocop]

@Valocop Are you working on this, or shall I give it a try?
@patriknw

Sorry for waiting, yes, you can try, unfortunately, I can't join right now