From 0ae718d067a4ec94ffba592824695234621f563e Mon Sep 17 00:00:00 2001
From: Kishore Nallan <kishorenc@gmail.com>
Date: Fri, 16 Jul 2021 12:07:44 +0530
Subject: [PATCH] Use all candidates of a given num_typo value.

Typo tokens threshold should not trigger when we have explored only some of the candidates of a given num_typo value.
---
 src/index.cpp                     | 14 ++++++++-----
 test/collection_specific_test.cpp | 33 +++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/src/index.cpp b/src/index.cpp
index 38ee7555..627729cc 100644
--- a/src/index.cpp
+++ b/src/index.cpp
@@ -910,6 +910,8 @@ void Index::search_candidates(const uint8_t & field_id,
     auto product = []( long long a, token_candidates & b ) { return a*b.candidates.size(); };
     long long int N = std::accumulate(token_candidates_vec.begin(), token_candidates_vec.end(), 1LL, product);
 
+    size_t last_cost = 0;
+
     for(long long n=0; n<N && n<combination_limit; ++n) {
         // every element in `query_suggestion` contains a token and its associated hits
         std::vector<art_leaf*> query_suggestion(token_candidates_vec.size());
@@ -921,6 +923,13 @@ void Index::search_candidates(const uint8_t & field_id,
         uint32_t total_cost = next_suggestion(token_candidates_vec, n, actual_query_suggestion,
                                               query_suggestion, token_bits);
 
+        //LOG(INFO) << "field_num_results: " << field_num_results << ", typo_tokens_threshold: " << typo_tokens_threshold;
+        if(total_cost != last_cost  && field_num_results >= typo_tokens_threshold) {
+            //break;
+        }
+
+        last_cost = total_cost;
+
         /*LOG(INFO) << "n: " << n;
         for(size_t i=0; i < actual_query_suggestion.size(); i++) {
             LOG(INFO) << "i: " << i << " - " << actual_query_suggestion[i]->key << ", ids: "
@@ -1019,11 +1028,6 @@ void Index::search_candidates(const uint8_t & field_id,
         }
 
         searched_queries.push_back(actual_query_suggestion);
-
-        //LOG(INFO) << "field_num_results: " << field_num_results << ", typo_tokens_threshold: " << typo_tokens_threshold;
-        if(field_num_results >= typo_tokens_threshold) {
-            break;
-        }
     }
 }
 
diff --git a/test/collection_specific_test.cpp b/test/collection_specific_test.cpp
index 52d5979b..ca9163c5 100644
--- a/test/collection_specific_test.cpp
+++ b/test/collection_specific_test.cpp
@@ -276,6 +276,39 @@ TEST_F(CollectionSpecificTest, MultiFieldArrayRepeatingTokens) {
     collectionManager.drop_collection("coll1");
 }
 
+TEST_F(CollectionSpecificTest, ExactMatchOnPrefix) {
+    std::vector<field> fields = {field("title", field_types::STRING, false),
+                                 field("points", field_types::INT32, false),};
+
+    Collection* coll1 = collectionManager.create_collection("coll1", 1, fields, "points").get();
+
+    nlohmann::json doc1;
+    doc1["id"] = "0";
+    doc1["title"] = "Yeshivah Gedolah High School";
+    doc1["points"] = 100;
+
+    nlohmann::json doc2;
+    doc2["id"] = "1";
+    doc2["title"] = "GED";
+    doc2["points"] = 50;
+
+    ASSERT_TRUE(coll1->add(doc1.dump()).ok());
+    ASSERT_TRUE(coll1->add(doc2.dump()).ok());
+
+    auto results = coll1->search("ged", {"title"}, "", {}, {}, {2}, 10,
+                                 1, FREQUENCY, {true}, Index::DROP_TOKENS_THRESHOLD,
+                                 spp::sparse_hash_set<std::string>(),
+                                 spp::sparse_hash_set<std::string>(), 10, "", 30, 5,
+                                 "", 1).get();
+
+    ASSERT_EQ(2, results["hits"].size());
+
+    ASSERT_EQ("1", results["hits"][0]["document"]["id"].get<std::string>());
+    ASSERT_EQ("0", results["hits"][1]["document"]["id"].get<std::string>());
+
+    collectionManager.drop_collection("coll1");
+}
+
 TEST_F(CollectionSpecificTest, PrefixWithTypos) {
     std::vector<field> fields = {field("title", field_types::STRING, false),
                                  field("points", field_types::INT32, false),};