Improve hit estimate for ImportedSearchContext.

1 files changed, 46 insertions, 1 deletions

diff --git a/searchlib/src/tests/attribute/imported_search_context/imported_search_context_test.cpp b/searchlib/src/tests/attribute/imported_search_context/imported_search_context_test.cpp
index 6cb0dec3c1f..847a992d241 100644
--- a/searchlib/src/tests/attribute/imported_search_context/imported_search_context_test.cpp
+++ b/searchlib/src/tests/attribute/imported_search_context/imported_search_context_test.cpp
@@ -6,6 +6,7 @@
 #include <vespa/searchlib/query/query_term_ucs4.h>
 #include <vespa/searchlib/queryeval/simpleresult.h>
 #include <vespa/searchlib/test/imported_attribute_fixture.h>
+#include <vespa/searchlib/test/mock_gid_to_lid_mapping.h>
 #include <vespa/vespalib/test/insertion_operators.h>
 #include <vespa/searchlib/queryeval/executeinfo.h>
 
@@ -75,13 +76,57 @@ bool is_strict_hit_with_weight(Iterator& iter, TermFieldMatchData& match,
             EXPECT_EQUAL(weight, match.getWeight()));
 }
 
-TEST_F("approximateHits() returns document count of reference attribute", Fixture) {
+TEST_F("approximateHits() returns document count of reference attribute when not using fast-search target attribute", Fixture) {
+    add_n_docs_with_undefined_values(*f.target_attr, 10);
     add_n_docs_with_undefined_values(*f.reference_attr, 101);
 
     auto ctx = f.create_context(word_term("foo"));
     EXPECT_EQUAL(101u, ctx->approximateHits());
 }
 
+TEST_F("approximateHits() estimates hits when using fast-search target attribute", Fixture(false, FastSearchConfig::ExplicitlyEnabled))
+{
+    constexpr uint32_t target_docs = 1000;
+    constexpr uint32_t docs = 10000;
+    constexpr uint32_t target_gids = 200;
+    f.target_attr->addReservedDoc();
+    add_n_docs_with_undefined_values(*f.target_attr, target_docs);
+    f.reference_attr->addReservedDoc();
+    add_n_docs_with_undefined_values(*f.reference_attr, docs);
+    auto target_attr = dynamic_cast<IntegerAttribute *>(f.target_attr.get());
+    // 2 documents with value 20, 110 documents with value 30.
+    for (uint32_t i = 1; i < 3; ++i) {
+        target_attr->update(i, 20);
+    }
+    for (uint32_t i = 10; i < 120; ++i) {
+        target_attr->update(i, 30);
+    }
+    f.target_attr->commit();
+    // Assign target gids
+    for (uint32_t i = 1; i <= target_gids; ++i) {
+        auto target_gid = dummy_gid(i);
+        f.mapper_factory->_map[target_gid] = i;
+        f.reference_attr->notifyReferencedPut(target_gid, i);
+    }
+    // Add 2 references to each target gid
+    for (uint32_t i = 1; i <= target_gids * 2; ++i) {
+        f.reference_attr->update(i, dummy_gid(((i - 1) % target_gids) + 1));
+    }
+    f.reference_attr->commit();
+    auto ctx = f.create_context(word_term("10"));
+    // Exact count: 0 target hits => 0
+    EXPECT_EQUAL(0u, ctx->approximateHits());
+    TermFieldMatchData match;
+    auto iter = f.create_iterator(*ctx, match, false);
+    EXPECT_TRUE(iter->matches_any() == Trinary::False);
+    ctx = f.create_context(word_term("20"));
+    // Exact count: 2 target hits, 2 docs / target doc => 2 * 2 = 4
+    EXPECT_EQUAL(4u, ctx->approximateHits());
+    ctx = f.create_context(word_term("30"));
+    // Approximation: 110 target hits => 110 * 10001 / 1001 = 1099
+    EXPECT_EQUAL(1099u, ctx->approximateHits());
+}
+
 TEST_F("attributeName() returns imported attribute name", Fixture) {
     auto ctx = f.create_context(word_term("foo"));
     EXPECT_EQUAL(f.default_imported_attr_name(), ctx->attributeName());