5 files changed, 35 insertions, 10 deletions
diff --git a/src/mongo/db/query/get_executor_test.cpp b/src/mongo/db/query/get_executor_test.cpp
index aca45d23026..431430259e8 100644
--- a/src/mongo/db/query/get_executor_test.cpp
+++ b/src/mongo/db/query/get_executor_test.cpp
@@ -37,9 +37,9 @@
 #include <string>
 
 #include "mongo/bson/simple_bsonobj_comparator.h"
+#include "mongo/db/exec/index_path_projection.h"
 #include "mongo/db/exec/projection_executor.h"
 #include "mongo/db/exec/projection_executor_builder.h"
-#include "mongo/db/exec/wildcard_projection.h"
 #include "mongo/db/json.h"
 #include "mongo/db/pipeline/expression_context_for_test.h"
 #include "mongo/db/query/projection_parser.h"
diff --git a/src/mongo/db/query/index_entry.h b/src/mongo/db/query/index_entry.h
index 6f69d388c9d..40313fdfed6 100644
--- a/src/mongo/db/query/index_entry.h
+++ b/src/mongo/db/query/index_entry.h
@@ -43,7 +43,8 @@
 namespace mongo {
 class CollatorInterface;
 class MatchExpression;
-class WildcardProjection;
+class IndexPathProjection;
+using WildcardProjection = IndexPathProjection;
 
 /**
  * A CoreIndexInfo is a representation of an index in the catalog with parsed information which is
@@ -69,6 +70,7 @@ struct CoreIndexInfo {
           collator(ci),
           wildcardProjection(wildcardProj) {
         // We always expect a projection executor for $** indexes, and none otherwise.
+        // TODO SERVER-67140: Add columnstoreProjection and invariant
         invariant((type == IndexType::INDEX_WILDCARD) == (wildcardProjection != nullptr));
     }
 
@@ -262,7 +264,7 @@ struct ColumnIndexEntry {
 
     std::string catalogName;
 
-    // TODO SERVER-63123: Projection, probably need some kind of disambiguator.
+    // TODO SERVER-67140: Projection, probably need some kind of disambiguator.
 };
 
 std::ostream& operator<<(std::ostream& stream, const IndexEntry::Identifier& ident);
diff --git a/src/mongo/db/query/projection_parser.cpp b/src/mongo/db/query/projection_parser.cpp
index 7110775621d..e093d840d9f 100644
--- a/src/mongo/db/query/projection_parser.cpp
+++ b/src/mongo/db/query/projection_parser.cpp
@@ -592,7 +592,7 @@ Projection parseAndAnalyze(boost::intrusive_ptr<ExpressionContext> expCtx,
                            const BSONObj& queryObj,
                            ProjectionPolicies policies,
                            bool shouldOptimize) {
-    if (!policies.findOnlyFeaturesAllowed()) {
+    if (!policies.emptyProjectionAllowed()) {
         // In agg-style syntax it is illegal to have an empty projection specification.
         uassert(51272, "projection specification must have at least one field", !obj.isEmpty());
     }
diff --git a/src/mongo/db/query/projection_policies.h b/src/mongo/db/query/projection_policies.h
index 09094227c86..1e9214f2515 100644
--- a/src/mongo/db/query/projection_policies.h
+++ b/src/mongo/db/query/projection_policies.h
@@ -55,6 +55,9 @@ struct ProjectionPolicies {
     // Whether $elemMatch, find() $slice and positional projection are allowed.
     enum class FindOnlyFeaturesPolicy { kBanFindOnlyFeatures, kAllowFindOnlyFeatures };
 
+    // Whether the empty projection, {}, is permitted.
+    enum class EmptyProjectionPolicy { kBanEmptyProjection, kAllowEmptyProjection };
+
     static const DefaultIdPolicy kDefaultIdPolicyDefault = DefaultIdPolicy::kIncludeId;
     static const ArrayRecursionPolicy kArrayRecursionPolicyDefault =
         ArrayRecursionPolicy::kRecurseNestedArrays;
@@ -62,46 +65,66 @@ struct ProjectionPolicies {
         ComputedFieldsPolicy::kAllowComputedFields;
     static const FindOnlyFeaturesPolicy kFindOnlyFeaturesPolicyDefault =
         FindOnlyFeaturesPolicy::kBanFindOnlyFeatures;
+    static const EmptyProjectionPolicy kEmptyProjectionPolicyDefault =
+        EmptyProjectionPolicy::kBanEmptyProjection;
 
     static ProjectionPolicies findProjectionPolicies() {
         return ProjectionPolicies{kDefaultIdPolicyDefault,
                                   kArrayRecursionPolicyDefault,
                                   kComputedFieldsPolicyDefault,
-                                  FindOnlyFeaturesPolicy::kAllowFindOnlyFeatures};
+                                  FindOnlyFeaturesPolicy::kAllowFindOnlyFeatures,
+                                  EmptyProjectionPolicy::kAllowEmptyProjection};
     }
 
     static ProjectionPolicies aggregateProjectionPolicies() {
         return ProjectionPolicies{kDefaultIdPolicyDefault,
                                   kArrayRecursionPolicyDefault,
                                   kComputedFieldsPolicyDefault,
-                                  FindOnlyFeaturesPolicy::kBanFindOnlyFeatures};
+                                  FindOnlyFeaturesPolicy::kBanFindOnlyFeatures,
+                                  kEmptyProjectionPolicyDefault};
     }
 
     static ProjectionPolicies wildcardIndexSpecProjectionPolicies() {
         return ProjectionPolicies{DefaultIdPolicy::kExcludeId,
                                   ArrayRecursionPolicy::kDoNotRecurseNestedArrays,
                                   ComputedFieldsPolicy::kBanComputedFields,
-                                  FindOnlyFeaturesPolicy::kBanFindOnlyFeatures};
+                                  FindOnlyFeaturesPolicy::kBanFindOnlyFeatures,
+                                  kEmptyProjectionPolicyDefault};
+    }
+
+    static ProjectionPolicies columnStoreIndexSpecProjectionPolicies() {
+        return ProjectionPolicies{kDefaultIdPolicyDefault,
+                                  ArrayRecursionPolicy::kDoNotRecurseNestedArrays,
+                                  ComputedFieldsPolicy::kBanComputedFields,
+                                  FindOnlyFeaturesPolicy::kBanFindOnlyFeatures,
+                                  EmptyProjectionPolicy::kAllowEmptyProjection};
     }
 
     ProjectionPolicies(
         DefaultIdPolicy idPolicy = kDefaultIdPolicyDefault,
         ArrayRecursionPolicy arrayRecursionPolicy = kArrayRecursionPolicyDefault,
         ComputedFieldsPolicy computedFieldsPolicy = kComputedFieldsPolicyDefault,
-        FindOnlyFeaturesPolicy findOnlyFeaturesPolicy = kFindOnlyFeaturesPolicyDefault)
+        FindOnlyFeaturesPolicy findOnlyFeaturesPolicy = kFindOnlyFeaturesPolicyDefault,
+        EmptyProjectionPolicy emptyProjectionPolicy = kEmptyProjectionPolicyDefault)
         : idPolicy(idPolicy),
           arrayRecursionPolicy(arrayRecursionPolicy),
           computedFieldsPolicy(computedFieldsPolicy),
-          findOnlyFeaturesPolicy(findOnlyFeaturesPolicy) {}
+          findOnlyFeaturesPolicy(findOnlyFeaturesPolicy),
+          emptyProjectionPolicy(emptyProjectionPolicy) {}
 
     const DefaultIdPolicy idPolicy;
     const ArrayRecursionPolicy arrayRecursionPolicy;
     const ComputedFieldsPolicy computedFieldsPolicy;
     const FindOnlyFeaturesPolicy findOnlyFeaturesPolicy;
+    const EmptyProjectionPolicy emptyProjectionPolicy;
 
     bool findOnlyFeaturesAllowed() const {
         return findOnlyFeaturesPolicy == FindOnlyFeaturesPolicy::kAllowFindOnlyFeatures;
     }
+
+    bool emptyProjectionAllowed() const {
+        return emptyProjectionPolicy == EmptyProjectionPolicy::kAllowEmptyProjection;
+    }
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/query/query_planner.cpp b/src/mongo/db/query/query_planner.cpp
index 6f37288e733..83cc6617d44 100644
--- a/src/mongo/db/query/query_planner.cpp
+++ b/src/mongo/db/query/query_planner.cpp
@@ -218,7 +218,7 @@ void tryToAddColumnScan(const QueryPlannerParams& params,
         return;
     }
 
-    // TODO SERVER-63123: Check if the columnar index actually provides the fields we need.
+    // TODO SERVER-67140: Check if the columnar index actually provides the fields we need.
     std::unique_ptr<MatchExpression> residualPredicate;
     StringMap<std::unique_ptr<MatchExpression>> filterSplitByColumn;
     if (params.options & QueryPlannerParams::GENERATE_PER_COLUMN_FILTERS) {