DBLE vs Mycat2

DBLE is free, open-source middleware for scaling MySQL through sharding. It uses the MySQL protocol and can replace MySQL in many cases without application code changes. Teams can configure hash, modulo, time-based, range-based, or custom sharding, along with global and ER tables. DBLE lists query routing, connection pooling, load balancing, automatic failover, read/write separation, master-slave expansion, and ZooKeeper cluster deployment. SQL support includes SQL 92 and MySQL dialect features such as joins, unions, grouping, ordering, and distinct queries; some features remain on its roadmap. Query optimization addresses global-table joins, sharded tables, ER relations, and subqueries. Distributed transactions use two-phase commit in normal or XA modes, with XA depending on MySQL 5.7 XA transactions, backend availability, and disk reliability. Security controls include password encryption, IP allowlists, and SQL denylists. Explain plans, MySQL-compatible slow logs, and slow-query reports support operations. DBLE is self-hosted on Linux and GPL-2.0 licensed. The open-source plan 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.