colsearch

ColSearch — the production search category for late-interaction retrieval. One node. CPU or GPU. MaxSim is the truth scorer. 1.58-bit ColBERT at 40 B/token. 3.12× FastPlaid on H100.

Renamed from voyager-index. pip install colsearch is the new home. The legacy import voyager_index path keeps working in 0.1.7 (with a one-line DeprecationWarning) and will be removed in 0.2.0. See CHANGELOG.md.

The pain

ColBERT-quality retrieval is table-stakes for serious RAG, and the production options force a choice you should not have to make.

• Managed SaaS — fast to start, hard to control, your data leaves the box.
• Distributed clusters — strong recall, expensive to operate.
• Offline benchmarks — great numbers, no API, no WAL, no recovery.

Most "production" stacks treat MaxSim as an optional rerank stage and lose its signal under aggressive shortlisting. Most engines that ship operationally drop late interaction entirely.

The solution

colsearch is a multi-vector native retrieval engine built around MaxSim as the final scorer — and engineered so a single machine can serve it.

• One-node deployment. No control plane, no orchestration tax.
• One contract across CPU and GPU. Rust SIMD on CPU, Triton + fused CUDA on GPU.
• Production-ready 1.58-bit kernel. ~40 B per token (~6.4× smaller than FP16), parity-tested on both lanes, NDCG@10 within ~1 pt of FP16 on BEIR. 3.12× geomean QPS over FastPlaid on BEIR-8 / H100 with the FP16 lane — see benchmarks/competitive_benchmark.md.
• Late-interaction native. ColBERT, ColPali, ColQwen out of the box.
• Database semantics. WAL, checkpoint, crash recovery, scroll, retrieve.
• Optional graph lane. The Latence sidecar augments first-stage retrieval — never required.

How

pip install "colsearch[full]"        # CPU-only host
pip install "colsearch[full,gpu]"    # GPU host
colsearch-server                     # OpenAPI at http://127.0.0.1:8080/docs

Python:

import numpy as np
from colsearch import Index

rng = np.random.default_rng(7)
docs = [rng.normal(size=(16, 128)).astype("float32") for _ in range(32)]
query = rng.normal(size=(16, 128)).astype("float32")

idx = Index("demo", dim=128, engine="shard", n_shards=32,
            k_candidates=256, compression="fp16")
idx.add(docs, ids=list(range(len(docs))))
print(idx.search(query, k=5)[0])

HTTP (base64 vector payloads, fp8 GPU scoring, ColBANDIT pruning):

import numpy as np, requests
from colsearch import encode_vector_payload

q = np.random.default_rng(7).normal(size=(16, 128)).astype("float32")
r = requests.post(
    "http://127.0.0.1:8080/collections/demo/search",
    json={"vectors": encode_vector_payload(q, dtype="float16"), "top_k": 5,
          "quantization_mode": "fp8", "use_colbandit": True},
    timeout=30,
)
print(r.json()["results"][0])

Docker:

docker build -f deploy/reference-api/Dockerfile -t colsearch .
docker run -p 8080:8080 -v "$(pwd)/data:/data" colsearch

Features

• Routing — LEMUR proxy router + FAISS MIPS shortlist, optional ColBANDIT query-time pruning.
• Scoring — Triton MaxSim and fused Rust MaxSim, FP16 / INT8 / FP8 / ROQ-4 / RROQ-1.58 / RROQ-4 with float rerank.
• Storage — safetensors shards, memory-mapped CPU, GPU-resident corpus mode.
• Hybrid — BM25 + dense fusion via RRF or Tabu Search refinement.
• Multimodal — text (ColBERT), images (ColPali / ColQwen), preprocessing for PDF / DOCX / XLSX.
• Operations — WAL, checkpoint, crash recovery, scroll, retrieve, multi-worker FastAPI.
• Optional graph lane — Latence sidecar for graph-aware rescue and provenance, additive to the OSS path.
• Optional groundedness lane — Latence Trace premium sidecar for post-generation hallucination scoring against retrieved chunk_ids or raw context. See the Groundedness sidecar guide and latence.ai for access.

Benchmarks

Headline competitive numbers (single-H100, BEIR-8, single-client sequential — same methodology FastPlaid publishes):

colsearch fp16/gpu beats FastPlaid GPU on 8 / 8 BEIR-8 datasets; the 1.58-bit lane wins 6 / 8 while shipping a 6.4× smaller index. Per-dataset rows, NDCG@10 quality, CPU lane, hardware/env block, and reproduction command live in benchmarks/competitive_benchmark.md.

The full 4-codec × BEIR-6 × 2-mode internal sweep (FP16 / INT8 / RROQ-1.58 / RROQ-4-Riem) lives in docs/benchmarks.md; raw per-cell JSONL with provenance under reports/beir_2026q2/.

Reproducible head-to-head against FastPlaid

A single-command benchmark runs colsearch against FastPlaid on FastPlaid's published BEIR-8 matrix using identical per-token embeddings for both libraries (so the comparison varies only the indexing/scoring engine, not the encoder model). Tutorial, including the recommended single-H100 cloud setup: docs/benchmarks/fast-plaid-head-to-head.md. Quick smoke (one small dataset, ~30 s on H100):

pip install fast-plaid pylate
python benchmarks/data/prepare_beir_datasets.py --datasets nfcorpus
python benchmarks/fast_plaid_head_to_head.py --datasets nfcorpus

Codecs

Compression.RROQ158 (group_size=128) is the default codec for newly built indexes. For dims that aren't a multiple of 128 the encoder transparently steps down to gs=64 / gs=32 with a log warning. Pass compression=Compression.FP16 (Python) or --compression fp16 (CLI) to opt out. Decision matrix and per-dim recipe: docs/guides/quantization-tuning.md. Math (RaBitQ extension + Riemannian log map + FWHT-rotated tangent ternary): docs/guides/rroq-mathematics.md.

Existing FP16 / RROQ158 / RROQ4_RIEM indexes load unchanged — the manifest carries the build-time codec.

Architecture

query (token / patch embeddings)
  → LEMUR routing MLP → FAISS ANN → candidate IDs
  → optional BM25 fusion · centroid pruning · ColBANDIT
  → exact MaxSim   (Rust SIMD CPU FP16/RROQ-1.58/RROQ-4-Riem  |  Triton + fused CUDA GPU FP16/INT8/FP8/ROQ-4/RROQ-1.58/RROQ-4-Riem)
  → optional FP16 rerank on top-N shortlist
  → optional Latence graph augmentation
  → top-K (or packed context)

Three execution modes share the same collection format and API contract: CPU exact (mmap → Rust fused), GPU streamed (CPU → GPU → Triton), and GPU corpus (fully VRAM-resident). Start with CPU, add GPU when latency matters.

Documentation

• Quickstart · Installation · Install from source
• Reference API Tutorial · HTTP endpoint reference · Python API
• Shard Engine Guide · Max-Performance Guide · Scaling Guide
• Latence Graph Sidecar Guide · Groundedness Sidecar Guide · Enterprise Control Plane
• Benchmarks And Methodology · Competitive Benchmark vs FastPlaid · Production Notes
• Full Feature Cookbook

Community And Project Health

• File a bug: bug report template
• Request a feature: feature request template
• Open a PR: pull request template
• Contributing guide: CONTRIBUTING.md
• Security policy: SECURITY.md
• Release process: RELEASING.md
• Code of Conduct: CODE_OF_CONDUCT.md

License & Commercial Use

This project is licensed under Creative Commons Attribution-NonCommercial 4.0 International (CC-BY-NC-4.0). It is free for non-commercial use only.

You may use, copy, modify, and redistribute colsearch for:

• research, evaluation, and benchmarking
• academic work and teaching
• personal projects and experimentation
• internal, non-revenue R&D inside an organization

You may not use colsearch, in whole or in part, for any commercial or revenue-generating purpose without a separate commercial license. This explicitly includes:

• selling, sublicensing, or relicensing the code
• offering it as a hosted, managed, or SaaS product
• embedding it in any product, service, or integration that you sell, license, or otherwise monetize
• using it to provide paid consulting deliverables built on top of it

For commercial licensing inquiries, contact commercial@latence.ai.

Carveout — vendored Qdrant subtree. The directory src/kernels/vendor/qdrant/ is a vendored copy of upstream qdrant/qdrant and remains under its original Apache-2.0 license; that license travels with those files into any derivative binaries. See LICENSING.md and internal/contracts/QDRANT_VENDORING.md for the full carveout.

Prior releases. Releases previously distributed under the voyager-index name (versions 0.1.0 through 0.1.6, Apache-2.0) remain available to recipients who already obtained them under their original license. The CC-BY-NC-4.0 license above and the colsearch package name apply to this source tree and to all 0.1.7+ releases made from it going forward.