SERVER-45363 Base weight for text index on exact match not possible match

(cherry picked from commit 4bb2ad4c48c07d267c98f5443e0984a5e1ef7209)

2 files changed, 45 insertions, 1 deletions

diff --git a/jstests/core/fts_index_wildcard_and_weight.js b/jstests/core/fts_index_wildcard_and_weight.js
new file mode 100644
index 00000000000..9397be5cb9a
--- /dev/null
+++ b/jstests/core/fts_index_wildcard_and_weight.js
@@ -0,0 +1,44 @@
+// Test that on a text index that matches all fields does not use a weight from a named field.
+// This test was designed to reproduce SERVER-45363.
+// @tags: [requires_fcv_44]
+//
+(function() {
+"use strict";
+var coll = db.getCollection(jsTestName());
+coll.drop();
+
+assert.commandWorked(coll.createIndex(
+    {"$**": "text"}, {name: "fullTextIndex", weights: {name: 500}, default_language: "english"}));
+assert.commandWorked(coll.insert({name: 'Spot', guardian: 'Kevin'}));
+assert.commandWorked(coll.insert({name: 'Kevin', guardian: 'Spot'}));
+var results = coll.aggregate([
+                      {$match: {$text: {$search: "Kevin"}}},
+                      {$sort: {score: {$meta: "textScore"}}},
+                      {$project: {name: 1, score: {$meta: "textScore"}}}
+                  ])
+                  .toArray();
+assert.gt(results[0].score, results[1].score);
+assert.eq(results[0].name, "Kevin");
+
+coll.drop();
+assert.commandWorked(coll.createIndex(
+    {"$**": "text"},
+    {name: "fullTextIndex", weights: {name: 500, tag: 250}, default_language: "english"}));
+assert.commandWorked(coll.insert({name: 'Spot', guardian: 'Kevin', special: 'Dog', tag: 'Nice'}));
+assert.commandWorked(coll.insert({name: 'Kevin', guardian: 'Spot', special: 'Human', tag: 'Mean'}));
+assert.commandWorked(
+    coll.insert({name: 'Whiskers', guardian: 'Carl', special: 'Cat', tag: 'Kevin'}));
+assert.commandWorked(
+    coll.insert({name: 'McFlufferson', guardian: 'Steve', special: 'Kevin', tag: 'Fluffy'}));
+
+results = coll.aggregate([
+                  {$match: {$text: {$search: "Kevin"}}},
+                  {$sort: {score: {$meta: "textScore"}}},
+                  {$project: {name: 1, score: {$meta: "textScore"}}}
+              ])
+              .toArray();
+assert.eq(results[0].name, "Kevin", results);
+assert.eq(results[1].name, "Whiskers", results);
+assert.gt(results[0].score, results[1].score, results);
+assert.eq(results[2].score, results[3].score, results);
+})();
diff --git a/src/mongo/db/fts/fts_element_iterator.cpp b/src/mongo/db/fts/fts_element_iterator.cpp
index c9666f0834a..00c0dd39134 100644
--- a/src/mongo/db/fts/fts_element_iterator.cpp
+++ b/src/mongo/db/fts/fts_element_iterator.cpp
@@ -143,7 +143,7 @@ FTSIteratorValue FTSElementIterator::advance() {
 
         // Is the current field an exact match on a weight?
         bool exactMatch = (possibleWeightMatch && i->first == dottedName);
-        double weight = (possibleWeightMatch ? i->second : DEFAULT_WEIGHT);
+        double weight = (exactMatch ? i->second : DEFAULT_WEIGHT);
 
         switch (elem.type()) {
             case String: