Epoch-based Optimistic Concurrency Control in Geo-replicated Databases

TL;DR

Minerva introduces an epoch-based optimistic concurrency control for geo-replicated databases, enabling high scalability and serializability with minimal coordination, outperforming existing systems in throughput and latency scenarios.

Contribution

It presents Minerva, a novel concurrency control protocol that combines epoch-based asynchronous replication with deterministic conflict resolution for scalable geo-distributed transactions.

Findings

Over 3x higher throughput compared to state-of-the-art systems.

Achieves 2.8x higher throughput under high network latency.

Effectively maintains serializability with minimal coordination.

Abstract

Geo-distribution is essential for modern online applications to ensure service reliability and high availability. However, supporting high-performance serializable transactions in geo-replicated databases remains a significant challenge. This difficulty stems from the extensive over-coordination inherent in distributed atomic commitment, concurrency control, and fault-tolerance replication protocols under high network latency. To address these challenges, we introduce Minerva, a unified distributed concurrency control designed for highly scalable multi-leader replication. Minerva employs a novel epoch-based asynchronous replication protocol that decouples data propagation from the commitment process, enabling continuous transaction replication. Optimistic concurrency control is used to allow any replicas to execute transactions concurrently and commit without coordination. In stead of aborting transactions when conflicts are detected, Minerva uses deterministic re-execution to resolve conflicts, ensuring serializability without sacrificing performance. To further enhance concurrency, we construct a conflict graph and use a maximum weight independent set algorithm to select the optimal subset of transactions for commitment, minimizing the number of re-executed transactions. Our evaluation demonstrates that Minerva significantly outperforms state-of-the-art replicated databases, achieving over $3\times$ higher throughput in scalability experiments and $2.8\times$ higher throughput during a high network latency simulation with the TPC-C benchmark.