Config & GraphParams

struct Config {
    std::uint16_t dimension{128};
    Metric metric{Metric::cosine};
    IndexType index_type{IndexType::hnsw};
    GraphParams graph_params{};
    Durability durability{Durability::sync_on_commit};
    AccessMode access_mode{AccessMode::read_write};
    std::size_t segment_size_bytes{64 * 1024 * 1024}; // 64MB default
};

struct GraphParams {
    std::size_t m{16};                   // Max bi-directional links per node
    std::size_t ef_construction{200};    // Search queue capacity during construction
    std::size_t ef_search{50};           // Search queue capacity during query time
    float compaction_ratio{0.2f};       // Tombstone threshold to trigger auto-vacuum
};

enum class Metric {
    cosine,
    euclidean,
    dot_product
};

enum class IndexType {
    hnsw,
    exact,
    ivf_flat,
    ivf_pq
};

enum class Durability {
    sync_on_commit,  // fsync WAL on every commit
    wal_only,        // write WAL without forcing fsync immediately
    in_memory        // skip disk writing completely
};

enum class AccessMode {
    read_write,
    read_only
};

elips::Config config;
config.dimension = 1536;
config.metric = elips::Metric::cosine;
config.index_type = elips::IndexType::hnsw;
config.graph_params.m = 32;
config.graph_params.ef_construction = 400;
config.graph_params.ef_search = 128;

elips::Config config;
config.dimension = 384;
config.metric = elips::Metric::dot_product;
config.index_type = elips::IndexType::hnsw;
config.graph_params.m = 12;
config.graph_params.ef_construction = 100;
config.graph_params.ef_search = 24;