Qdrant 1.16 - Tiered Multitenancy & Disk-Efficient Vector Search - Qdrant

Introduces the ACORN-1 algorithm as a new search option for filtered vector search. ACORN explores second-hop neighbors in the HNSW graph when direct neighbors are filtered out, improving search accuracy at the expense of performance, especially when multiple low-selectivity filters are applied. This feature can be enabled on a per-query basis via the `acorn` parameter and does not require index-time changes. Benchmarks show a significant improvement in accuracy (97.20% vs 53.34%) at a moderate latency increase (13.86 ms vs 1.25 ms) when using multiple low-selectivity filters.