What is the pgvector limit on rows and performance at scale?

pgvector has no hard row limit, but practical scale depends on available memory and disk. HNSW indexes typically scale to 10 to 100 million vectors per Postgres instance with adequate RAM, beyond which dedicated vector databases often perform better due to specialized architecture. Performance degrades when the index exceeds memory and must spill to disk, so provisioning enough RAM for the index size is critical. Partitioning by tenant or time, plus scaling reads with replicas, extends pgvector's useful range.