Actually I'm not sure it's necessary... Quoting:

[4:12 PM] Yoann Rodière: @Sanne So I had a look, and backends actually already don't rely on sharding strategies directly, they use an OperationDispatcher (either "transactional" or streaming)
[4:13 PM] Yoann Rodière: @Sanne In your case, you're doing really strange stuff, using the shard for deletion to execute purge/flush works... Is this on purpose?
[4:14 PM] Yoann Rodière: @Sanne See https://github.com/Sanne/infinispan/blob/UpgradeSearch/query/src/main/java/org/infinispan/query/impl... and https://github.com/Sanne/infinispan/blob/UpgradeSearch/query/src/main/java/org/infinispan/query/impl...
[4:15 PM] Yoann Rodière: I'd recommend using a StreamingOperationDispatcher. It's an impl class, but ExtendedBatchBackend already uses impl classes, so it doesn't seem to be the main problem.
[4:31 PM] Yoann Rodière: @Sanne Here is a patch: https://github.com/Sanne/infinispan/compare/UpgradeSearch...yrodiere:UpgradeSearch

Sanne Grinovero Maybe we can close this ticket?