Heimdall Database Proxy vs Mycat2

Heimdall Database Proxy is a data access layer between an application and its database, routing, caching, and securing SQL queries. It can send reads to replicas and writes to primary databases, with replication-lag detection to support consistency. Frequently used queries can be cached with automatic expiry and invalidation rules to reduce database load and latency. Connection pooling can reduce front-side to back-side connections by up to a 1000:1 ratio. The proxy provides live SQL visibility, bottleneck identification, and auto-tuning recommendations, and can run as a transparent sidecar on-premise or in the cloud. Supported databases include MySQL, PostgreSQL, Amazon RDS, Oracle, SQL Server, MariaDB, DB2, Greenplum, and Redshift. Listed cloud integrations include AWS, Azure, Oracle, Google Cloud, and Redis. Active Directory integration supports authentication and authorization. Enterprise Plus includes data masking, GDPR auditing, and honey-tokens. A free Greenplum Community Edition is available for Greenplum use, with pooling, LDAP synchronization for one server, and SQL performance analytics. The AWS Marketplace listing offers a free 30-day trial; technical support for the Community Edition requires an Enterprise upgrade.

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.