Tech Optimizer
July 22, 2026
Google has introduced a preview of its columnar engine-accelerated HNSW feature for AlloyDB, enhancing vector search throughput by up to four times for users of the pgvector extension in PostgreSQL. This improvement is aimed at approximate nearest neighbor searches using HNSW across large datasets. AlloyDB utilizes a columnar engine that allows HNSW indexes to reside in memory, improving throughput and recall metrics. In benchmark tests on the GloVe 100 Angular dataset, queries per second increased by approximately 4.2x to 4.9x, with recall improving from about 0.78 to over 0.94 at a throughput of around 350 queries per second. The columnar engine's design bypasses traditional PostgreSQL buffer management bottlenecks, enhancing efficiency during graph traversal. The memory architecture is distinct from basic caching techniques, and the feature requires no changes to application code. Users must enable the columnar engine and index caching flags to utilize this feature. Benchmarks were conducted on an AlloyDB C4A machine with 16 virtual CPUs.
