FILTERED VECTOR SEARCH: WHAT ACORN FIXES, AND WHAT FIXES ACORN

Summary from the TLDR Data newsletter

Metadata filters can break vector search by splitting the HNSW graph into disconnected islands. Qdrant compares filterable HNSW, ACORN expansion, full scans, and planner choices on one million vectors, showing when extra index-time edges beat query-time repair and when ACORN helps.