Index params

Intro to Indexes

For more detailed informations about indexes, please refer to Milvus documentation index chapter.

Index building parameters and search parameters.

Index	building parameter	search parameter
FLAT	NULL	NULL
BIN_FLAT	NULL	NULL
IVF_FLAT	nlist	nprobe
BIN_IVF_FLAT	nlist	nprobe
IVF_PQ	m, nlist	nprobe
IVF_SQ8	nlist	nprobe
IVF_SQ8_HYBRID	nlist	nprobe
ANNOY	n_trees	search_k
HNSW	M, efConstruction	ef
RHNSW_PQ	M, efConstruction,PQM	ef
RHNSW_SQ	M, efConstruction	ef
RNSG	search_length, out_degree, candidate_pool_size, knng	search_length

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Index building parameters with description, validation range.

Building parameter	description	validation range
nlist	Number of cluster units	[1, 65536]
m	Number of factors of product quantization	CPU-only Milvus: m ≡ dim (mod m); GPU-enabled Milvus: m ∈ {1, 2, 3, 4, 8, 12, 16, 20, 24, 28, 32, 40, 48, 56, 64, 96}, and (dim / m) ∈ {1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24, 28, 32}. (m x 1024) ≥ MaxSharedMemPerBlock of your graphics card.
M	Maximum degree of the node	[4, 64]
efConstruction	Take effect in stage of index construction, search scope	[8, 512]
PQM	m for PQ	CPU-only Milvus: m ≡ dim (mod m)
search_length	Number of query iterations	[10, 300]
out_degree	Maximum out-degree of the node	[5, 300]
candidate_pool_size	Candidate pool size of the node	[50, 1000]
knng	Number of nearest neighbors	[5, 300]
n_trees	The number of methods of space division	[1, 1024]

Search in index parameters with description, validation range and recommender values.

Search parameter	description	validation range
nprobe	Number of inverted file cell to probe	CPU: [1, nlist], GPU: [1, min(2048, nlist)]
ef	Search scope	[topk, 32768]
search_length	Number of query iterations	[10, 300]
search_k	The number of nodes to search. -1 means 5% of the whole data	{-1} U [top_k, n*n_trees]