fix hnsw param use

nucliadb_vectors/src/data_point/disk_hnsw.rs

@@ -112,7 +112,7 @@ impl<'a> Iterator for EdgeIter<'a> {
             let edge = f32_from_le_bytes(&buf[crnt..(crnt + EDGE_LEN)]);
             crnt += EDGE_LEN;
             self.crnt = crnt;
-            Some((Address(node), Edge { dist: edge }))
+            Some((Address(node), edge))
         }
     }
 }
@@ -138,7 +138,7 @@ impl DiskHnsw {
             length += USIZE_LEN;
             for (cnx, edge) in hnsw.get_layer(layer).get_out_edges(node) {
                 buf.write_all(&cnx.0.to_le_bytes())?;
-                buf.write_all(&edge.dist.to_le_bytes())?;
+                buf.write_all(&edge.to_le_bytes())?;
                 length += CNX_LEN;
             }
         }
@@ -242,9 +242,9 @@ mod tests {
     fn hnsw_test() {
         let no_nodes = 3;
         let cnx0 = vec![
-            vec![(Address(1), Edge { dist: 1.0 })],
-            vec![(Address(2), Edge { dist: 2.0 })],
-            vec![(Address(3), Edge { dist: 3.0 })],
+            vec![(Address(1), 1.0)],
+            vec![(Address(2), 2.0)],
+            vec![(Address(3), 3.0)],
         ];
         let layer0 = RAMLayer {
             out: cnx0
@@ -253,18 +253,15 @@ mod tests {
                 .map(|(i, c)| (Address(i), c.clone()))
                 .collect(),
         };
-        let cnx1 = vec![
-            vec![(Address(1), Edge { dist: 4.0 })],
-            vec![(Address(2), Edge { dist: 5.0 })],
-        ];
+        let cnx1 = vec![vec![(Address(1), 4.0)], vec![(Address(2), 5.0)]];
         let layer1 = RAMLayer {
             out: cnx1
                 .iter()
                 .enumerate()
                 .map(|(i, c)| (Address(i), c.clone()))
                 .collect(),
         };
-        let cnx2 = vec![vec![(Address(1), Edge { dist: 6.0 })]];
+        let cnx2 = vec![vec![(Address(1), 6.0)]];
         let layer2 = RAMLayer {
             out: cnx2
                 .iter()

nucliadb_vectors/src/data_point/ops_hnsw.rs

@@ -116,7 +116,7 @@ impl<'a, DR: DataRetriever> HnswOps<'a, DR> {
         k_neighbours: usize,
         mut candidates: Vec<(Address, Edge)>,
     ) -> Vec<(Address, Edge)> {
-        candidates.sort_unstable_by_key(|(n, d)| std::cmp::Reverse(Cnx(*n, d.dist)));
+        candidates.sort_unstable_by_key(|(n, d)| std::cmp::Reverse(Cnx(*n, *d)));
         candidates.dedup_by_key(|(addr, _)| *addr);
         candidates.truncate(k_neighbours);
         candidates
@@ -152,7 +152,7 @@ impl<'a, DR: DataRetriever> HnswOps<'a, DR> {
                 }
                 Some((down, _)) => {
                     let mut sorted_out: Vec<_> = layer.get_out_edges(down).collect();
-                    sorted_out.sort_by(|a, b| b.1.dist.total_cmp(&a.1.dist));
+                    sorted_out.sort_by(|a, b| b.1.total_cmp(&a.1));
                     sorted_out.into_iter().for_each(|(new_candidate, _)| {
                         if !visited_nodes.contains(&new_candidate) {
                             candidates.push_back(new_candidate);
@@ -216,14 +216,15 @@ impl<'a, DR: DataRetriever> HnswOps<'a, DR> {
     ) -> Vec<Address> {
         use params::*;
         let neighbours = self.layer_search::<&RAMLayer>(x, layer, ef_construction(), entry_points);
+        let neighbours = self.select_neighbours_heuristic(m_max(), neighbours);
         let mut needs_repair = HashSet::new();
         let mut result = Vec::with_capacity(neighbours.len());
         layer.add_node(x);
         for (y, dist) in neighbours.iter().copied() {
             result.push(y);
-            layer.add_edge(x, Edge { dist }, y);
-            layer.add_edge(y, Edge { dist }, x);
-            if layer.no_out_edges(y) > 2 * m_max() {
+            layer.add_edge(x, dist, y);
+            layer.add_edge(y, dist, x);
+            if layer.no_out_edges(y) > m_max() {
                 needs_repair.insert(y);
             }
         }

nucliadb_vectors/src/data_point/params.rs

@@ -28,7 +28,7 @@ pub fn level_factor() -> f64 {
 
 /// Upper limit to the number of out-edges a embedding can have.
 pub const fn m_max() -> usize {
-    30
+    60
 }
 
 /// Number of bi-directional links created for every new element.

nucliadb_vectors/src/data_point/ram_hnsw.rs

@@ -33,10 +33,7 @@ pub struct EntryPoint {
     pub layer: usize,
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, PartialOrd, Serialize, Deserialize)]
-pub struct Edge {
-    pub dist: f32,
-}
+pub type Edge = f32;
 
 #[derive(Default, Clone)]
 pub struct RAMLayer {