Paper 2020/472

Bracing A Transaction DAG with A Backbone Chain

Shuyang Tang

Abstract

Directed Acyclic Graph (DAG) is becoming an intriguing direction for distributed ledger structure due to its great potential in improving the scalability of distributed ledger systems. Among existing DAG-based ledgers, one promising category is transaction DAG, namely, treating each transaction as a graph vertex. In this paper, we propose Haootia, a novel two-layer framework of consensus, with a ledger in the form of a transaction DAG built on top of a delicately designed PoW-based backbone chain. By elaborately devising the principle of transaction linearizations, we achieve a secure and scalable DAG-based consensus. By implementing Haootia, we conclude that, with a rotating committee of size 46 and a confirmation latency around 20 seconds, Haootia achieves a throughput around 7500 TPS which is overwhelming compared with all formally analyzed DAG-based consensus schemes to date and all existing non-DAG-based ones to our knowledge.