Heimdall Database Proxy vs Pgpool-II

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.

Pgpool-II is free, self-hosted middleware positioned between PostgreSQL servers and database clients. It relays PostgreSQL protocol messages, reuses matching server connections to reduce overhead, and distributes SELECT queries across replicated databases. High-availability functions include automatic failover, Watchdog, quorum, and split-brain prevention. Additional features include replication, online recovery, connection limiting, and an in-memory query cache. The project is available in binary and source formats, including RPM packages for Red Hat Enterprise Linux and compatible distributions; Debian and Ubuntu users are directed to PostgreSQL community packages. Authentication supports trust, clear-text password, MD5, SCRAM-SHA-256, certificates, PAM, and LDAP, but not GSSAPI. SSL can protect frontend and backend traffic when enabled; it is off by default and requires OpenSSL support. Community assistance is available through mailing lists and GitHub Issues, while SRA OSS K.K. offers commercial support, consulting, and integration. The license permits use, modification, copying, and distribution without a fee.