Hybrid Search & Feature Benchmarks
Alpha Parameter
The alpha parameter controls the balance between dense (semantic) and sparse (keyword) retrieval.
| Mode | Alpha | Strategy | Mean | Median | Range |
|---|---|---|---|---|---|
| Dense-only | 1.0 | dense | 19.2ms | 17ms | 16-26ms |
| Sparse-only | 0.0 | sparse | 8.8ms | 9ms | 7-11ms |
| Hybrid (historical default) | 0.7 | hybrid | 19.6ms | 16ms | 16-27ms |
These latency measurements predate the calibrated 0.5 default and retain 0.7 only as
the configuration used for that historical run.
Choosing alpha
- alpha=0.0 — Fastest. Pure BM25 keyword matching. Best when you know exact terms.
- alpha=0.5 — Current default. Equal weighting reduces dense drift on lexical queries.
- alpha=0.7 — Historical benchmark configuration with a stronger semantic bias.
- alpha=1.0 — Pure semantic. Best for conceptual queries where exact keywords may not appear.
Reranking
Cross-encoder reranking via fastembed TextCrossEncoder with Xenova/ms-marco-MiniLM-L-6-v2.
| Metric | Value |
|---|---|
| Status | PASS |
| Model | Xenova/ms-marco-MiniLM-L-6-v2 |
| Mean latency (3 runs) | 1,469.67ms |
| Median latency (3 runs) | 1,468ms |
| Range | 1,435-1,506ms |
| Top result quality | bank_of_america_2024.pdf ranked #1 (score 1.0) |
Reranked Results (top 3)
Query: "bank of america financial results"
| Rank | Document | Chunk | Rerank Score |
|---|---|---|---|
| 1 | bank_of_america_2024.pdf | bank_of_america_2024.pdf:7 | 1.0000 |
| 2 | bank_of_america_2024.pdf | bank_of_america_2024.pdf:8 | 0.9377 |
| 3 | bank_of_america_2024.pdf | bank_of_america_2024.pdf:9 | 0.7958 |
Reranking adds measured overhead
Use --rerank selectively for precision-critical queries. In this historical run, reranking averaged 1,469.67ms while hybrid search at alpha=0.7 averaged 19.6ms.
Metadata Filters
Document-level filtering narrowed results to a specific document:
just search "financial results" -- --filter document_id=bank_of_america_2024.pdf
| Metric | Value |
|---|---|
| Status | PASS |
| Results returned | 10 |
| Total matching chunks | 12 |
| Query time | 30ms |
Pagination
| Test | Status | Details |
|---|---|---|
| Page 1 (limit=5, offset=0) | PASS | 5 results, has_more=true, total=10, query_time=19ms |
| Page 2 (limit=5, offset=5) | PASS | 5 results, has_more=true, total=20, query_time=17ms |
just search "bank" -- --limit 5 --offset 0
just search "bank" -- --limit 5 --offset 5