Citus

As an extension, Citus retains all PostgreSQL features—like advanced joins, updates, foreign keys, and extensions such as PostGIS—allowing seamless integration with existing tools and workflows without sacrificing capabilities.

Enables sharding tables across a cluster to combine CPU, memory, and I/O capacity, supporting high transaction throughputs and large datasets, as evidenced by use cases like multi-tenant SaaS and real-time analytics.

The distributed query engine efficiently routes transactional queries to specific shards and parallelizes analytical queries across the cluster, handling both under high concurrency, as described in the architecture section.

Columnar storage significantly reduces data size—e.g., 25 MB vs 651 MB in the README example—and speeds up scan-intensive queries for analytics, though it's limited to append-only workloads.