Indexes
VSAG ships a family of index implementations that share a single builder-style API,
one serialization format, and one set of operations (Build, Add, KnnSearch,
RangeSearch, Remove, Serialize / Deserialize, …). They differ in the data
structures and trade-offs they use under the hood.
The pages in this section cover the actively developed indexes:
| Index | Page | Best for |
|---|---|---|
hgraph | HGraph | General-purpose, high-recall graph with rich quantization options |
lazy_hgraph | LazyHGraph | Small-to-growing FP32 collections that start exact and later convert to HGraph |
ivf | IVF | Partition-based search, high-throughput batch queries, large corpora |
sindi | SINDI | Sparse vectors (BM25 / learned sparse) on inner-product |
simq | SIMQ | ColBERT-style multi-vector retrieval (MaxSim) |
sindi_v2 | SINDI_V2 | Sparse vectors (BM25 / learned sparse) on inner-product; supports both in-memory and disk-based I/O |
pyramid | Pyramid | Multi-tenant or tag-partitioned corpora with hierarchical paths |
brute_force is also available as an exact-search baseline (see
Creating an Index and examples/cpp/105_index_brute_force.cpp).
Parameter conventions
All indexes share the same top-level build fields:
| Field | Values | Notes |
|---|---|---|
dim | positive integer | Vector dimensionality; fixed after build |
dtype | float32 / float16 / bfloat16 / int8 / sparse | sparse is for SINDI / SINDI_V2 |
metric_type | l2 / ip / cosine | Must match at query time (SINDI / SINDI_V2 are ip only) |
Index-specific build parameters live under the index_param sub-object; search-time
parameters live under a sub-object named after the index (e.g. hgraph, ivf,
sindi, sindi_v2, pyramid). LazyHGraph also uses the hgraph search object after it
converts to graph phase. Concrete schemas are documented on each page and enumerated in
Index Parameters.