SPQR

What SPQR is

SPQR is a self-hosted PostgreSQL query router for scaling databases horizontally through sharding. It can extract a sharding key from a query and choose a matching key range and shard when possible. Keys can use one column or multiple columns, while SQL comments can specify a key or direct a query to a shard. Applications connect using the PostgreSQL protocol, and SPQR includes router and coordinator administrative consoles accessible through psql. It supports one-phase and two-phase commit strategies; two-phase commit provides atomicity across shards and requires max_prepared_transactions greater than zero on every shard. SPQR can migrate data between shards to balance workload, and the project says it has handled terabytes of data and 100K+ queries per second. It supports managed PostgreSQL services and names pgx and JDBC as compatible driver examples. SPQR is free and open source under the PostgreSQL Global Development Group License, with Docker and configuration-file deployment instructions. Its FAQ cautions against complex cross-shard queries, multi-shard modifying transactions, and OLAP workloads, and reports a roughly 10–30% performance drop versus vanilla PostgreSQL depending on workload.