Merge pull request #22217 from vespa-engine/geirst/improve-nearest-neighbor-visit-tracing

Improve nearest neighbor blueprint debug tracing

3 files changed, 20 insertions, 33 deletions

diff --git a/searchlib/src/tests/attribute/tensorattribute/tensorattribute_test.cpp b/searchlib/src/tests/attribute/tensorattribute/tensorattribute_test.cpp
index 1d3305d2c1a..ec75a0d6d06 100644
--- a/searchlib/src/tests/attribute/tensorattribute/tensorattribute_test.cpp
+++ b/searchlib/src/tests/attribute/tensorattribute/tensorattribute_test.cpp
@@ -1041,7 +1041,6 @@ public:
             100100.25,
             global_filter_lower_limit, 1.0);
         EXPECT_EQUAL(11u, bp->getState().estimate().estHits);
-        EXPECT_EQUAL(approximate, bp->may_approximate());
         EXPECT_EQUAL(100100.25 * 100100.25, bp->get_distance_threshold());
         return bp;
     }
@@ -1068,7 +1067,6 @@ TEST_F("NN blueprint handles empty filter", NearestNeighborBlueprintFixture)
     auto empty_filter = GlobalFilter::create();
     bp->set_global_filter(*empty_filter);
     EXPECT_EQUAL(3u, bp->getState().estimate().estHits);
-    EXPECT_TRUE(bp->may_approximate());
     EXPECT_EQUAL(NNBA::INDEX_TOP_K, bp->get_algorithm());
 }
 
@@ -1081,7 +1079,6 @@ TEST_F("NN blueprint handles strong filter", NearestNeighborBlueprintFixture)
     auto strong_filter = GlobalFilter::create(std::move(filter));
     bp->set_global_filter(*strong_filter);
     EXPECT_EQUAL(1u, bp->getState().estimate().estHits);
-    EXPECT_TRUE(bp->may_approximate());
     EXPECT_EQUAL(NNBA::INDEX_TOP_K_WITH_FILTER, bp->get_algorithm());
 }
 
@@ -1099,7 +1096,6 @@ TEST_F("NN blueprint handles weak filter", NearestNeighborBlueprintFixture)
     auto weak_filter = GlobalFilter::create(std::move(filter));
     bp->set_global_filter(*weak_filter);
     EXPECT_EQUAL(3u, bp->getState().estimate().estHits);
-    EXPECT_TRUE(bp->may_approximate());
     EXPECT_EQUAL(NNBA::INDEX_TOP_K_WITH_FILTER, bp->get_algorithm());
 }
 
@@ -1112,7 +1108,6 @@ TEST_F("NN blueprint handles strong filter triggering brute force search", Neare
     auto strong_filter = GlobalFilter::create(std::move(filter));
     bp->set_global_filter(*strong_filter);
     EXPECT_EQUAL(11u, bp->getState().estimate().estHits);
-    EXPECT_FALSE(bp->may_approximate());
     EXPECT_EQUAL(NNBA::BRUTE_FORCE_FALLBACK, bp->get_algorithm());
 }
 
diff --git a/searchlib/src/vespa/searchlib/queryeval/nearest_neighbor_blueprint.cpp b/searchlib/src/vespa/searchlib/queryeval/nearest_neighbor_blueprint.cpp
index bdcbb3db633..73eaa773c53 100644
--- a/searchlib/src/vespa/searchlib/queryeval/nearest_neighbor_blueprint.cpp
+++ b/searchlib/src/vespa/searchlib/queryeval/nearest_neighbor_blueprint.cpp
@@ -89,6 +89,7 @@ NearestNeighborBlueprint::NearestNeighborBlueprint(const queryeval::FieldSpec& f
       _found_hits(),
       _algorithm(Algorithm::BRUTE_FORCE),
       _global_filter(GlobalFilter::create()),
+      _global_filter_set(false),
       _global_filter_hits(),
       _global_filter_hit_ratio()
 {
@@ -122,51 +123,41 @@ void
 NearestNeighborBlueprint::set_global_filter(const GlobalFilter &global_filter)
 {
     _global_filter = global_filter.shared_from_this();
+    _global_filter_set = true;
     auto nns_index = _attr_tensor.nearest_neighbor_index();
-    LOG(debug, "set_global_filter with: %s / %s / %s",
-        (_approximate ? "approximate" : "exact"),
-        (nns_index ? "nns_index" : "no_index"),
-        (_global_filter->has_filter() ? "has_filter" : "no_filter"));
     if (_approximate && nns_index) {
         uint32_t est_hits = _attr_tensor.get_num_docs();
         if (_global_filter->has_filter()) {
             uint32_t max_hits = _global_filter->filter()->countTrueBits();
-            LOG(debug, "set_global_filter getNumDocs: %u / max_hits %u", est_hits, max_hits);
             double max_hit_ratio = static_cast<double>(max_hits) / est_hits;
             if (max_hit_ratio < _global_filter_lower_limit) {
-                _approximate = false;
                 _algorithm = Algorithm::BRUTE_FORCE_FALLBACK;
-                LOG(debug, "too many hits filtered out, using brute force implementation");
             } else {
                 est_hits = std::min(est_hits, max_hits);
             }
             _global_filter_hits = max_hits;
             _global_filter_hit_ratio = max_hit_ratio;
         }
-        if (_approximate) {
+        if (_algorithm != Algorithm::BRUTE_FORCE_FALLBACK) {
             est_hits = std::min(est_hits, _target_num_hits);
             setEstimate(HitEstimate(est_hits, false));
-            perform_top_k();
-            LOG(debug, "perform_top_k found %zu hits", _found_hits.size());
+            perform_top_k(nns_index);
         }
     }
 }
 
 void
-NearestNeighborBlueprint::perform_top_k()
+NearestNeighborBlueprint::perform_top_k(const search::tensor::NearestNeighborIndex* nns_index)
 {
-    auto nns_index = _attr_tensor.nearest_neighbor_index();
-    if (_approximate && nns_index) {
-        auto lhs = _query_tensor->cells();
-        uint32_t k = _target_num_hits;
-        if (_global_filter->has_filter()) {
-            auto filter = _global_filter->filter();
-            _found_hits = nns_index->find_top_k_with_filter(k, lhs, *filter, k + _explore_additional_hits, _distance_threshold);
-            _algorithm = Algorithm::INDEX_TOP_K_WITH_FILTER;
-        } else {
-            _found_hits = nns_index->find_top_k(k, lhs, k + _explore_additional_hits, _distance_threshold);
-            _algorithm = Algorithm::INDEX_TOP_K;
-        }
+    auto lhs = _query_tensor->cells();
+    uint32_t k = _target_num_hits;
+    if (_global_filter->has_filter()) {
+        auto filter = _global_filter->filter();
+        _found_hits = nns_index->find_top_k_with_filter(k, lhs, *filter, k + _explore_additional_hits, _distance_threshold);
+        _algorithm = Algorithm::INDEX_TOP_K_WITH_FILTER;
+    } else {
+        _found_hits = nns_index->find_top_k(k, lhs, k + _explore_additional_hits, _distance_threshold);
+        _algorithm = Algorithm::INDEX_TOP_K;
     }
 }
 
@@ -191,14 +182,15 @@ NearestNeighborBlueprint::visitMembers(vespalib::ObjectVisitor& visitor) const
     visitor.visitString("query_tensor", _query_tensor->type().to_spec());
     visitor.visitInt("target_num_hits", _target_num_hits);
     visitor.visitInt("explore_additional_hits", _explore_additional_hits);
-    visitor.visitBool("approximate", _approximate);
+    visitor.visitBool("wanted_approximate", _approximate);
     visitor.visitBool("has_index", _attr_tensor.nearest_neighbor_index());
     visitor.visitString("algorithm", to_string(_algorithm));
     visitor.visitInt("top_k_hits", _found_hits.size());
 
     visitor.openStruct("global_filter", "GlobalFilter");
-    visitor.visitBool("is_set", (_global_filter != nullptr));
-    visitor.visitBool("has_filter", (_global_filter && _global_filter->has_filter()));
+    visitor.visitBool("wanted", getState().want_global_filter());
+    visitor.visitBool("set", _global_filter_set);
+    visitor.visitBool("calculated", _global_filter->has_filter());
     visitor.visitFloat("lower_limit", _global_filter_lower_limit);
     visitor.visitFloat("upper_limit", _global_filter_upper_limit);
     if (_global_filter_hits.has_value()) {
diff --git a/searchlib/src/vespa/searchlib/queryeval/nearest_neighbor_blueprint.h b/searchlib/src/vespa/searchlib/queryeval/nearest_neighbor_blueprint.h
index 7922036dc42..7637c4dd6b7 100644
--- a/searchlib/src/vespa/searchlib/queryeval/nearest_neighbor_blueprint.h
+++ b/searchlib/src/vespa/searchlib/queryeval/nearest_neighbor_blueprint.h
@@ -41,10 +41,11 @@ private:
     std::vector<search::tensor::NearestNeighborIndex::Neighbor> _found_hits;
     Algorithm _algorithm;
     std::shared_ptr<const GlobalFilter> _global_filter;
+    bool _global_filter_set;
     std::optional<uint32_t> _global_filter_hits;
     std::optional<double> _global_filter_hit_ratio;
 
-    void perform_top_k();
+    void perform_top_k(const search::tensor::NearestNeighborIndex* nns_index);
 public:
     NearestNeighborBlueprint(const queryeval::FieldSpec& field,
                              const tensor::ITensorAttribute& attr_tensor,
@@ -60,7 +61,6 @@ public:
     const vespalib::eval::Value& get_query_tensor() const { return *_query_tensor; }
     uint32_t get_target_num_hits() const { return _target_num_hits; }
     void set_global_filter(const GlobalFilter &global_filter) override;
-    bool may_approximate() const { return _approximate; }
     Algorithm get_algorithm() const { return _algorithm; }
     double get_distance_threshold() const { return _distance_threshold; }