Heimdall Database Proxy vs SPQR

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.

SPQR is a self-hosted query router for horizontally scaling PostgreSQL through sharding. It can extract a sharding key from a query and route it to the relevant key range and shard when possible; keys can use one column or several. Queries can also specify a key or shard in a SQL comment. Applications connect using the PostgreSQL protocol, and the router and coordinator provide administrative consoles accessible through psql. SPQR supports one-phase and two-phase commit strategies; two-phase commit provides atomicity across shards and requires max_prepared_transactions greater than zero on each shard. The system can move data between shards to balance workload, and the project describes reducing transferred ranges to limit locking impact. Its documentation includes Docker and configuration-file deployment instructions. SPQR is free and distributed under the PostgreSQL Global Development Group License. The FAQ cautions that it is not suited to complex cross-shard queries, transactions modifying multiple shards or OLAP workloads, and reports a roughly 10–30% performance drop versus vanilla PostgreSQL depending on workload.