Akka Cassandra Persistence: multiple manifests?

[Alan Burlison]

I've been looking at the implementation of Cassandra persistence,
there appears to be two manifests that get persisted to Cassandra, one
related to the PersistentRepr and one related to the serializer that's
being used.

https://github.com/akka/akka-persistence-cassandra/blob/master/src/main/scala/akka/persistence/cassandra/journal/CassandraJournal.scala#L392

Why is is the PersistentRepr one saved? I don't seem to be able to
find it being used anywhere.

Thanks,

--
Alan Burlison
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[Patrik Nordwall]

The event's serialization manifest is stored in "ser_manifest" and the PersistentRepr.manifest is stored in "event_manifest".

I can see the confusion :) and I guess the naming went bad in one of many refactorings. Can't change column names now.

The two manifests have different purposes.

"ser_manifest" together with "ser_id" is used for the serialization of the event (payload).

PersistentRepr.manifest is used by the event adapters (in akka-persistence).

/Patrik

--
Alan Burlison
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Patrik Nordwall
Akka Tech Lead
Lightbend -  Reactive apps on the JVM
Twitter: @patriknw

[Alan Burlison]

On 18/01/2017 19:32, Patrik Nordwall wrote:

> The event's serialization manifest is stored in "ser_manifest" and the
> PersistentRepr.manifest is stored in "event_manifest".
> I can see the confusion :) and I guess the naming went bad in one of many
> refactorings. Can't change column names now.

It's no big deal ;-)

> The two manifests have different purposes.
> "ser_manifest" together with "ser_id" is used for the serialization of the
> event (payload).

Yep, that's what I'd figured out.

> PersistentRepr.manifest is used by the event adapters (in akka-persistence).

Ahah, that's the bit I was missing - where they were used. Thanks :-)

https://github.com/akka/akka/blob/v2.4.16/akka-persistence/src/main/scala/akka/persistence/journal/EventAdapter.scala#L39

--
Alan Burlison
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