SERVER-36362 Do not consider an 'allPaths' index for a $text query

3 files changed, 74 insertions, 6 deletions

diff --git a/src/mongo/db/query/planner_ixselect.cpp b/src/mongo/db/query/planner_ixselect.cpp
index eb9cbfbb55f..70deacf2d5b 100644
--- a/src/mongo/db/query/planner_ixselect.cpp
+++ b/src/mongo/db/query/planner_ixselect.cpp
@@ -686,6 +686,7 @@ void QueryPlannerIXSelect::_rateIndices(MatchExpression* node,
 // static
 void QueryPlannerIXSelect::stripInvalidAssignments(MatchExpression* node,
                                                    const vector<IndexEntry>& indices) {
+    stripInvalidAssignmentsToAllPathsIndexes(node, indices);
     stripInvalidAssignmentsToTextIndexes(node, indices);
 
     if (MatchExpression::GEO != node->matchType() &&
@@ -874,6 +875,34 @@ void QueryPlannerIXSelect::stripInvalidAssignmentsToPartialIndices(
 }
 
 //
+// AllPaths index invalid assignments.
+//
+void QueryPlannerIXSelect::stripInvalidAssignmentsToAllPathsIndexes(
+    MatchExpression* root, const vector<IndexEntry>& indices) {
+    for (size_t idx = 0; idx < indices.size(); ++idx) {
+        // Skip over all indexes except $**.
+        if (indices[idx].type != IndexType::INDEX_ALLPATHS) {
+            continue;
+        }
+        // If we have a $** index, check whether we have a TEXT node in the MatchExpression tree.
+        const std::function<MatchExpression*(MatchExpression*)> findTextNode = [&](auto* node) {
+            if (node->matchType() == MatchExpression::TEXT) {
+                return node;
+            }
+            for (size_t i = 0; i < node->numChildren(); ++i) {
+                if (auto* foundNode = findTextNode(node->getChild(i)))
+                    return foundNode;
+            }
+            return static_cast<MatchExpression*>(nullptr);
+        };
+        // If so, remove the $** index from the node's relevant tags.
+        if (auto* textNode = findTextNode(root)) {
+            removeIndexRelevantTag(textNode, idx);
+        }
+    }
+}
+
+//
 // Text index quirks
 //
 
diff --git a/src/mongo/db/query/planner_ixselect.h b/src/mongo/db/query/planner_ixselect.h
index b1834a1610e..b0181fab150 100644
--- a/src/mongo/db/query/planner_ixselect.h
+++ b/src/mongo/db/query/planner_ixselect.h
@@ -228,6 +228,17 @@ private:
                                                          const std::vector<IndexEntry>& indices);
 
     /**
+     * This function strips RelevantTag assignments to expanded 'allPaths' indexes, in cases where
+     * the assignment is incompatible with the query.
+     *
+     * Specifically, if the query has a TEXT node with both 'text' and 'allPaths' indexes present,
+     * then the 'allPaths' index will mark itself as relevant to the '_fts' path reported by the
+     * TEXT node. We therefore remove any such misassigned 'allPaths' tags here.
+     */
+    static void stripInvalidAssignmentsToAllPathsIndexes(MatchExpression* root,
+                                                         const std::vector<IndexEntry>& indices);
+
+    /**
      * This function strips RelevantTag assignments to partial indices, where the assignment is
      * incompatible with the index's filter expression.
      *
diff --git a/src/mongo/db/query/query_planner_all_paths_index_test.cpp b/src/mongo/db/query/query_planner_all_paths_index_test.cpp
index 0e6374252c1..c758a0c48a8 100644
--- a/src/mongo/db/query/query_planner_all_paths_index_test.cpp
+++ b/src/mongo/db/query/query_planner_all_paths_index_test.cpp
@@ -585,12 +585,6 @@ TEST_F(QueryPlannerAllPathsTest, InBasicOrEquivalent) {
         "bounds: {'$_path': [['a','a',true,true]], a: [[1,1,true,true],[2,2,true,true]]}}}}}");
 }
 
-// TODO SERVER-35335: Add testing for Min/Max.
-// TODO SERVER-36517: Add testing for DISTINCT_SCAN.
-// TODO SERVER-35336: Add testing for partialFilterExpression.
-// TODO SERVER-35331: Add testing for hints.
-// TODO SERVER-36145: Add testing for non-blocking sort.
-
 //
 // Index intersection tests.
 //
@@ -668,4 +662,38 @@ TEST_F(QueryPlannerAllPathsTest, AllPathsIndexDoesNotParticipateInIndexIntersect
         "{fetch: {filter:{b:{$gt:10}}, node: {ixscan: {filter: null, pattern: {$_path:1, a:1}}}}}");
 }
 
+//
+// AllPaths and $text index tests.
+//
+
+TEST_F(QueryPlannerAllPathsTest, AllPathsIndexDoesNotSupplyCandidatePlanForTextSearch) {
+    addAllPathsIndex(BSON("$**" << 1));
+    addIndex(BSON("a" << 1 << "_fts"
+                      << "text"
+                      << "_ftsx"
+                      << 1));
+
+    // Confirm that the allPaths index generates candidate plans for queries which do not include a
+    // $text predicate.
+    runQuery(fromjson("{a: 10, b: 10}"));
+    ASSERT_EQUALS(getNumSolutions(), 2U);
+    assertSolutionExists(
+        "{fetch: {filter: {b: 10}, node: {ixscan: {filter: null, pattern: {'$_path': 1, a: 1}}}}}");
+    assertSolutionExists(
+        "{fetch: {filter: {a: 10}, node: {ixscan: {filter: null, pattern: {'$_path': 1, b: 1}}}}}");
+
+    // Confirm that the allPaths index does not produce any candidate plans when a query includes a
+    // $text predicate, even for non-$text predicates which may be present in the query.
+    runQuery(fromjson("{a: 10, b: 10, $text: {$search: 'banana'}}"));
+    ASSERT_EQUALS(getNumSolutions(), 1U);
+    assertSolutionExists(
+        "{fetch: {filter: {b: 10}, node: {text: {prefix: {a: 10}, search: 'banana'}}}}");
+}
+
+// TODO SERVER-35335: Add testing for Min/Max.
+// TODO SERVER-36517: Add testing for DISTINCT_SCAN.
+// TODO SERVER-35336: Add testing for partialFilterExpression.
+// TODO SERVER-35331: Add testing for hints.
+// TODO SERVER-36145: Add testing for non-blocking sort.
+
 }  // namespace mongo