Underneath it uses Tephra (https://github.com/caskdata/tephra https://github.com/caskdata/tephra) as the distributed transaction manager for HBase together with

Underneath it uses Tephra (https://github.com/caskdata/tephra https://github.com/caskdata/tephra) as the distributed transaction manager for HBase together with a queue implementation on HBase to provide exactly-once processing.