SERVER-72465: Support CWI in validateNumericPathComponents function

2 files changed, 35 insertions, 3 deletions

diff --git a/src/mongo/db/query/planner_wildcard_helpers.cpp b/src/mongo/db/query/planner_wildcard_helpers.cpp
index b3eba5b13a5..998087894f4 100644
--- a/src/mongo/db/query/planner_wildcard_helpers.cpp
+++ b/src/mongo/db/query/planner_wildcard_helpers.cpp
@@ -251,10 +251,20 @@ std::set<FieldRef> generateFieldNameOrArrayIndexPathSet(const MultikeyComponents
 bool validateNumericPathComponents(const MultikeyPaths& multikeyPaths,
                                    const std::set<FieldRef>& includedPaths,
                                    const FieldRef& queryPath) {
+    // Find the position of the Wildcard's MultikeyComponents in the paths, we assume that the
+    // wildcard field is the only one that can be multikey.
+    auto wildcardComponent = std::find_if(multikeyPaths.begin(),
+                                          multikeyPaths.end(),
+                                          [](const MultikeyComponents& c) { return !c.empty(); });
+    if (wildcardComponent == multikeyPaths.end()) {
+        // If no MultikeyComponents just return.
+        return true;
+    }
+
     // Find the positions of all multikey path components in 'queryPath' that have a numerical path
     // component immediately after. For a queryPath of 'a.2.b' this will return position 0; that is,
     // 'a'. If no such multikey path was found, we are clear to proceed with planning.
-    const auto arrayIndices = findArrayIndexPathComponents(multikeyPaths.front(), queryPath);
+    const auto arrayIndices = findArrayIndexPathComponents(*wildcardComponent, queryPath);
     if (arrayIndices.empty()) {
         return true;
     }
diff --git a/src/mongo/db/query/planner_wildcard_helpers_test.cpp b/src/mongo/db/query/planner_wildcard_helpers_test.cpp
index 93ec840e4be..24d4a965661 100644
--- a/src/mongo/db/query/planner_wildcard_helpers_test.cpp
+++ b/src/mongo/db/query/planner_wildcard_helpers_test.cpp
@@ -113,14 +113,14 @@ TEST(PlannerWildcardHelpersTest, Expand_CompoundWildcardIndex_WithProjection) {
     IndexEntryMock wildcardIndex{
         BSON("e.f" << 1 << "$**" << 1 << "m.n" << 1), BSON("a" << 1), {FieldRef{"a"_sd}}};
 
-    stdx::unordered_set<std::string> fields{"a", "b"};
+    stdx::unordered_set<std::string> fields{"a.c", "b"};
     std::vector<IndexEntry> expandedIndexes{};
     expandWildcardIndexEntry(*wildcardIndex.indexEntry, fields, &expandedIndexes);
 
     MultikeyPaths expectedMks{{}, {0}, {}};
     ASSERT_EQ(1, expandedIndexes.size());
     ASSERT_BSONOBJ_EQ(expandedIndexes.front().keyPattern,
-                      BSON("e.f" << 1 << "a" << 1 << "m.n" << 1));
+                      BSON("e.f" << 1 << "a.c" << 1 << "m.n" << 1));
     ASSERT_TRUE(expandedIndexes.front().multikey);
     ASSERT_EQ(1, expandedIndexes.front().wildcardFieldPos);
     ASSERT_EQ(expectedMks, expandedIndexes.front().multikeyPaths);
@@ -159,4 +159,26 @@ TEST(PlannerWildcardHelpersTest, Expand_CompoundWildcardIndex_WithoutProjection)
     }
 }
 
+TEST(PlannerWildcardHelpersTest, Expand_CompoundWildcardIndex_NumericComponents) {
+    RAIIServerParameterControllerForTest controller("featureFlagCompoundWildcardIndexes", true);
+
+    IndexEntryMock wildcardIndex{BSON("e.f" << 1 << "$**" << 1 << "m.n" << 1),
+                                 BSON("a.0" << 1 << "b" << 1),
+                                 {FieldRef{"a"_sd}}};
+
+    stdx::unordered_set<std::string> fields{"a.0.b", "b"};
+    std::vector<IndexEntry> expandedIndexes{};
+    expandWildcardIndexEntry(*wildcardIndex.indexEntry, fields, &expandedIndexes);
+
+    // Expanded IndexEntry {e.f: 1, a.0.b: 1, m.n: 1} is exclauded since this is the case when the
+    // query path lies along a $** projection through an array index. See comment to
+    // 'validateNumericPathComponents' in planner_wildcard_helper.cpp function for details.
+    MultikeyPaths expectedMks{{}, {}, {}};
+    ASSERT_EQ(1, expandedIndexes.size());
+    ASSERT_BSONOBJ_EQ(expandedIndexes.front().keyPattern,
+                      BSON("e.f" << 1 << "b" << 1 << "m.n" << 1));
+    ASSERT_FALSE(expandedIndexes.front().multikey);
+    ASSERT_EQ(expectedMks, expandedIndexes.front().multikeyPaths);
+}
+
 }  // namespace mongo::wildcard_planning