Struct cuvsIvfPqIndexParams 

#[repr(C)]
pub struct cuvsIvfPqIndexParams {

    pub metric: cuvsDistanceType,
    pub metric_arg: f32,
    pub add_data_on_build: bool,
    pub n_lists: u32,
    pub kmeans_n_iters: u32,
    pub kmeans_trainset_fraction: f64,
    pub pq_bits: u32,
    pub pq_dim: u32,
    pub codebook_kind: cuvsIvfPqCodebookGen,
    pub force_random_rotation: bool,
    pub conservative_memory_allocation: bool,
    pub max_train_points_per_pq_code: u32,
    pub codes_layout: cuvsIvfPqListLayout,
}

@brief Supplemental parameters to build IVF-PQ Index

Fields

metric: cuvsDistanceType

Distance type.

metric_arg: f32

The argument used by some distance metrics.

add_data_on_build: bool

Whether to add the dataset content to the index, i.e.:

• true means the index is filled with the dataset vectors and ready to search after calling build.
• false means build only trains the underlying model (e.g. quantizer or clustering), but the index is left empty; you’d need to call extend on the index afterwards to populate it.

n_lists: u32

The number of inverted lists (clusters)

Hint: the number of vectors per cluster (n_rows/n_lists) should be approximately 1,000 to 10,000.

kmeans_n_iters: u32

The number of iterations searching for kmeans centers (index building).

kmeans_trainset_fraction: f64

The fraction of data to use during iterative kmeans building.

pq_bits: u32

The bit length of the vector element after compression by PQ.

Possible values: [4, 5, 6, 7, 8].

Hint: the smaller the ‘pq_bits’, the smaller the index size and the better the search performance, but the lower the recall.

pq_dim: u32

The dimensionality of the vector after compression by PQ. When zero, an optimal value is selected using a heuristic.

NB: pq_dim * pq_bits must be a multiple of 8.

Hint: a smaller ‘pq_dim’ results in a smaller index size and better search performance, but lower recall. If ‘pq_bits’ is 8, ‘pq_dim’ can be set to any number, but multiple of 8 are desirable for good performance. If ‘pq_bits’ is not 8, ‘pq_dim’ should be a multiple of 8. For good performance, it is desirable that ‘pq_dim’ is a multiple of 32. Ideally, ‘pq_dim’ should be also a divisor of the dataset dim.

codebook_kind: cuvsIvfPqCodebookGen

How PQ codebooks are created.

force_random_rotation: bool

Apply a random rotation matrix on the input data and queries even if dim % pq_dim == 0.

Note: if dim is not multiple of pq_dim, a random rotation is always applied to the input data and queries to transform the working space from dim to rot_dim, which may be slightly larger than the original space and and is a multiple of pq_dim (rot_dim % pq_dim == 0). However, this transform is not necessary when dim is multiple of pq_dim (dim == rot_dim, hence no need in adding “extra” data columns / features).

By default, if dim == rot_dim, the rotation transform is initialized with the identity matrix. When force_random_rotation == true, a random orthogonal transform matrix is generated regardless of the values of dim and pq_dim.

conservative_memory_allocation: bool

By default, the algorithm allocates more space than necessary for individual clusters (list_data). This allows to amortize the cost of memory allocation and reduce the number of data copies during repeated calls to extend (extending the database).

The alternative is the conservative allocation behavior; when enabled, the algorithm always allocates the minimum amount of memory required to store the given number of records. Set this flag to true if you prefer to use as little GPU memory for the database as possible.

max_train_points_per_pq_code: u32

The max number of data points to use per PQ code during PQ codebook training. Using more data points per PQ code may increase the quality of PQ codebook but may also increase the build time. The parameter is applied to both PQ codebook generation methods, i.e., PER_SUBSPACE and PER_CLUSTER. In both cases, we will use pq_book_size * max_train_points_per_pq_code training points to train each codebook.

codes_layout: cuvsIvfPqListLayout

Memory layout of the IVF-PQ list data.

• CUVS_IVF_PQ_LIST_LAYOUT_FLAT: Codes are stored contiguously, one vector’s codes after another.
• CUVS_IVF_PQ_LIST_LAYOUT_INTERLEAVED: Codes are interleaved for optimized search performance. This is the default and recommended for search workloads.

Trait Implementations

impl Clone for cuvsIvfPqIndexParams

fn clone(&self) -> cuvsIvfPqIndexParams

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for cuvsIvfPqIndexParams

impl Debug for cuvsIvfPqIndexParams

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.