
Filtered Vector Search: What ACORN Fixes, and What Fixes ACORN - Qdrant
8/7/2026
This post introduces and benchmarks ACORN-1, a query-time algorithm for improving filtered vector search performance in Qdrant. It details how ACORN-1 addresses the issue of graph connectivity degradation caused by metadata filters in HNSW. The post provides a comparative analysis of ACORN-1 against Filterable HNSW (an index-time optimization) and the default query planner, using specific benchmarks with single and double filters. It identifies scenarios where ACORN-1 excels (e.g., large value groups in indexed fields) and where other strategies are superior (e.g., Filterable HNSW for dense intersections, payload index for very sparse results). The contribution includes performance metrics, latency figures, and recall scores under various filtering conditions.
















































