HeliosProxy vs Mycat2

HeliosProxy is a self-hosted, programmable PostgreSQL data-plane for routing connections, handling failover, replaying traffic, and supporting database upgrades. It provides session, transaction, and statement pooling, with multiplexing up to 100:1. Routing can account for replica lag, workload type, and failing backends through circuit breaking. Cache options include local memory, Redis-backed storage, and semantic tiers, with invalidation when writes occur. Transaction Replay can move sessions to a new primary and optionally replay reads or transactions when conditions permit, although prepared statements, temporary tables, open cursors, advisory locks, and extended-protocol SET statements are not restored. A WebAssembly plugin runtime offers five hook points, Ed25519 verification, and OCI distribution. The admin console includes topology, plugin, chaos, shadow-execution, and traffic-replay panels. Authentication supports JWT, OAuth 2.0, LDAP, and API keys. HeliosProxy works with PostgreSQL 12+ and compatible databases, and deployment documentation covers Docker, Kubernetes, and standalone setups. It is open source under Apache 2.0 and costs nothing.

Mycat2 is free, open-source distributed relational database middleware for Linux and self-hosted deployment. It supports distributed SQL queries and the MySQL communication protocol while connecting to multiple backend databases through the Java ecosystem. Its query engine handles MySQL syntax and value types, rule- and cost-based optimization, and an independent physical execution engine. Data fragmentation is described as improving query processing. Users can customize and load sharding, serial-number and load-balancing algorithms. A project DSL manipulates physical query plans, forwards SQL and caches result sets. The README currently supports Java 8 only. Release notes for v1.22-2022-6-25 list ClickHouse as a backend for SELECT and INSERT, without returning auto-increment values. They also describe SQL permission interception, RSA encryption for user.json, and recycling inactive backend connections after a default 180-second timeout. The repository identifies an Apache License from 2023.8.