Update build parameter defaults (#176)

Internal testing shows better performance with new defaults.

Author: mihaic

bindings/python/src/vamana.cpp

@@ -454,7 +454,7 @@ void wrap(py::module& m) {
                     longer construction time. Should be larger than `graph_max_degree`.
                 max_candidate_pool_size: Limit on the number of candidates to consider
                     for neighbor updates. Should be larger than `window_size`.
-                    The default value is ``graph_max_degree`` * 2.
+                    The default value is ``window_size`` * 3.
                 prune_to: Amount candidate lists will be pruned to when exceeding the
                     target max degree. In general, setting this to slightly less than
                     ``graph_max_degree`` will yield faster index building times. Default:

include/svs/index/vamana/index.h

@@ -1013,7 +1013,7 @@ void verify_and_set_default_index_parameters(
 ) {
     // Set default values
     if (parameters.max_candidate_pool_size == svs::UNSIGNED_INTEGER_PLACEHOLDER) {
-        parameters.max_candidate_pool_size = 2 * parameters.graph_max_degree;
+        parameters.max_candidate_pool_size = 3 * parameters.window_size;
     }
 
     if (parameters.prune_to == svs::UNSIGNED_INTEGER_PLACEHOLDER) {

include/svs/lib/preprocessor.h

@@ -178,7 +178,7 @@ namespace svs {
 inline constexpr size_t UNSIGNED_INTEGER_PLACEHOLDER = std::numeric_limits<size_t>::max();
 inline constexpr float FLOAT_PLACEHOLDER = std::numeric_limits<float>::max();
 inline constexpr float VAMANA_GRAPH_MAX_DEGREE_DEFAULT = 32;
-inline constexpr float VAMANA_WINDOW_SIZE_DEFAULT = 64;
+inline constexpr float VAMANA_WINDOW_SIZE_DEFAULT = 200;
 inline constexpr bool VAMANA_USE_FULL_SEARCH_HISTORY_DEFAULT = true;
 inline constexpr float VAMANA_ALPHA_MINIMIZE_DEFAULT = 1.2;
 inline constexpr float VAMANA_ALPHA_MAXIMIZE_DEFAULT = 0.95;

tests/svs/index/vamana/dynamic_index_2.cpp

@@ -670,10 +670,10 @@ CATCH_TEST_CASE("Dynamic Vamana Index Default Parameters", "[parameter][vamana]"
             index.get_construction_window_size() == svs::VAMANA_WINDOW_SIZE_DEFAULT
         );
         CATCH_REQUIRE(
-            index.get_max_candidates() == 2 * svs::VAMANA_GRAPH_MAX_DEGREE_DEFAULT
+            index.get_max_candidates() == 3 * svs::VAMANA_WINDOW_SIZE_DEFAULT
         );
         CATCH_REQUIRE(
             index.get_full_search_history() == svs::VAMANA_USE_FULL_SEARCH_HISTORY_DEFAULT
         );
     }
-}
+}

tests/svs/index/vamana/index.cpp

@@ -255,10 +255,10 @@ CATCH_TEST_CASE("Vamana Index Default Parameters", "[parameter][vamana]") {
             index.get_construction_window_size() == svs::VAMANA_WINDOW_SIZE_DEFAULT
         );
         CATCH_REQUIRE(
-            index.get_max_candidates() == 2 * svs::VAMANA_GRAPH_MAX_DEGREE_DEFAULT
+            index.get_max_candidates() == 3 * svs::VAMANA_WINDOW_SIZE_DEFAULT
         );
         CATCH_REQUIRE(
             index.get_full_search_history() == svs::VAMANA_USE_FULL_SEARCH_HISTORY_DEFAULT
         );
     }
-}
+}