SERVER-68310 Filter out PartialSchemaRequirements which are unconstrained and avoid generating SargableNodes for nodes with empty PartialSchemaRequirements

2 files changed, 53 insertions, 6 deletions

diff --git a/src/mongo/db/query/optimizer/cascades/logical_rewriter.cpp b/src/mongo/db/query/optimizer/cascades/logical_rewriter.cpp
index a7f83d11406..7a499b0ec18 100644
--- a/src/mongo/db/query/optimizer/cascades/logical_rewriter.cpp
+++ b/src/mongo/db/query/optimizer/cascades/logical_rewriter.cpp
@@ -655,16 +655,27 @@ static void convertFilterToSargableNode(ABT::reference_type node,
         return;
     }
 
-    for (const auto& [key, req] : conversion->_reqMap) {
+    // Remove any partial schema requirments which do not constrain their input
+    for (auto it = conversion->_reqMap.cbegin(); it != conversion->_reqMap.cend();) {
         uassert(6624111,
                 "Filter partial schema requirement must contain a variable name.",
-                !key._projectionName.empty());
+                !it->first._projectionName.empty());
         uassert(6624112,
                 "Filter partial schema requirement cannot bind.",
-                !req.hasBoundProjectionName());
-        uassert(6624113,
-                "Filter partial schema requirement must have a range.",
-                !isIntervalReqFullyOpenDNF(req.getIntervals()));
+                !it->second.hasBoundProjectionName());
+        if (isIntervalReqFullyOpenDNF(it->second.getIntervals())) {
+            it = conversion->_reqMap.erase(it);
+        } else {
+            ++it;
+        }
+    }
+
+    // If the filter has no constraints after removing no-ops, then rewrite the filter with a
+    // predicate using the constant True.
+    if (conversion->_reqMap.empty()) {
+        ctx.addNode(make<FilterNode>(Constant::boolean(true), filterNode.getChild()),
+                    isSubstitution);
+        return;
     }
 
     // If in substitution mode, disallow retaining original predicate. If in exploration mode, only
diff --git a/src/mongo/db/query/optimizer/logical_rewriter_optimizer_test.cpp b/src/mongo/db/query/optimizer/logical_rewriter_optimizer_test.cpp
index 3196110ac8c..62b5467c2fe 100644
--- a/src/mongo/db/query/optimizer/logical_rewriter_optimizer_test.cpp
+++ b/src/mongo/db/query/optimizer/logical_rewriter_optimizer_test.cpp
@@ -1492,5 +1492,41 @@ TEST(LogicalRewriter, SargableCE) {
         phaseManager.getMemo());
 }
 
+TEST(LogicalRewriter, RemoveNoopFilter) {
+    using namespace properties;
+    PrefixId prefixId;
+
+    ABT scanNode = make<ScanNode>("ptest", "test");
+
+    ABT filterANode = make<FilterNode>(
+        make<EvalFilter>(make<PathGet>("a", make<PathCompare>(Operations::Gte, Constant::minKey())),
+                         make<Variable>("ptest")),
+        std::move(scanNode));
+
+    ABT rootNode = make<RootNode>(properties::ProjectionRequirement{ProjectionNameVector{"ptest"}},
+                                  std::move(filterANode));
+
+    OptPhaseManager phaseManager({OptPhaseManager::OptPhase::MemoSubstitutionPhase},
+                                 prefixId,
+                                 {{{"test", {{}, {}}}}},
+                                 DebugInfo::kDefaultForTests);
+    ABT latest = std::move(rootNode);
+    ASSERT_TRUE(phaseManager.optimize(latest));
+
+    ASSERT_EXPLAIN_V2(
+        "Root []\n"
+        "|   |   projections: \n"
+        "|   |       ptest\n"
+        "|   RefBlock: \n"
+        "|       Variable [ptest]\n"
+        "Filter []\n"
+        "|   Const [true]\n"
+        "Scan [test]\n"
+        "    BindBlock:\n"
+        "        [ptest]\n"
+        "            Source []\n",
+        latest);
+}
+
 }  // namespace
 }  // namespace mongo::optimizer