SERVER-55099 Update $_internalUnpackBucket serialization and parsing

8 files changed, 174 insertions, 62 deletions

diff --git a/src/mongo/db/exec/bucket_unpacker.h b/src/mongo/db/exec/bucket_unpacker.h
index 9c505bc1682..fd159092efa 100644
--- a/src/mongo/db/exec/bucket_unpacker.h
+++ b/src/mongo/db/exec/bucket_unpacker.h
@@ -29,6 +29,7 @@
 
 #pragma once
 
+#include <algorithm>
 #include <set>
 
 #include "mongo/bson/bsonobj.h"
@@ -182,7 +183,10 @@ private:
  */
 inline bool eraseMetaFromFieldSetAndDetermineIncludeMeta(BucketUnpacker::Behavior unpackerBehavior,
                                                          BucketSpec* bucketSpec) {
-    if (!bucketSpec->metaField) {
+    if (!bucketSpec->metaField ||
+        std::find(bucketSpec->computedMetaProjFields.cbegin(),
+                  bucketSpec->computedMetaProjFields.cend(),
+                  *bucketSpec->metaField) != bucketSpec->computedMetaProjFields.cend()) {
         return false;
     } else if (auto itr = bucketSpec->fieldSet.find(*bucketSpec->metaField);
                itr != bucketSpec->fieldSet.end()) {
diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.cpp b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.cpp
index 664028e21be..4eb1d2ac615 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.cpp
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.cpp
@@ -31,6 +31,9 @@
 
 #include "mongo/platform/basic.h"
 
+#include <algorithm>
+#include <iterator>
+
 #include "mongo/db/pipeline/document_source_internal_unpack_bucket.h"
 
 #include <string>
@@ -287,6 +290,7 @@ boost::intrusive_ptr<DocumentSource> DocumentSourceInternalUnpackBucket::createF
     auto hasIncludeExclude = false;
     std::vector<std::string> fields;
     auto bucketMaxSpanSeconds = 0;
+    std::vector<std::string> computedMetaProjFields;
     for (auto&& elem : specElem.embeddedObject()) {
         auto fieldName = elem.fieldNameStringData();
         if (fieldName == "include" || fieldName == "exclude") {
@@ -325,13 +329,28 @@ boost::intrusive_ptr<DocumentSource> DocumentSourceInternalUnpackBucket::createF
                     metaField.find('.') == std::string::npos);
             bucketSpec.metaField = std::move(metaField);
         } else if (fieldName == "bucketMaxSpanSeconds") {
-            uassert(5509900,
+            uassert(5510600,
                     "bucketMaxSpanSeconds field must be an integer",
                     elem.type() == BSONType::NumberInt);
-            uassert(5509901,
+            uassert(5510601,
                     "bucketMaxSpanSeconds field must be greater than zero",
                     elem._numberInt() > 0);
             bucketMaxSpanSeconds = elem._numberInt();
+        } else if (fieldName == "computedMetaProjFields") {
+            uassert(5509900,
+                    "computedMetaProjFields field must be an array",
+                    elem.type() == BSONType::Array);
+
+            for (auto&& elt : elem.embeddedObject()) {
+                uassert(5509901,
+                        "computedMetaProjFields field element must be a string",
+                        elt.type() == BSONType::String);
+                auto field = elt.valueStringData();
+                uassert(5509902,
+                        "computedMetaProjFields field element must be a single-element field path",
+                        field.find('.') == std::string::npos);
+                bucketSpec.computedMetaProjFields.emplace_back(field);
+            }
         } else {
             uasserted(5346506,
                       str::stream()
@@ -343,7 +362,7 @@ boost::intrusive_ptr<DocumentSource> DocumentSourceInternalUnpackBucket::createF
             "The $_internalUnpackBucket stage requires a timeField parameter",
             specElem[timeseries::kTimeFieldName].ok());
 
-    uassert(5509902,
+    uassert(5510602,
             "The $_internalUnpackBucket stage requires a bucketMaxSpanSeconds parameter",
             specElem["bucketMaxSpanSeconds"].ok());
 
@@ -361,13 +380,32 @@ void DocumentSourceInternalUnpackBucket::serializeToArray(
     for (auto&& field : spec.fieldSet) {
         fields.emplace_back(field);
     }
-    out.addField(behavior, Value{fields});
+    if (((_bucketUnpacker.includeMetaField() &&
+          _bucketUnpacker.behavior() == BucketUnpacker::Behavior::kInclude) ||
+         (!_bucketUnpacker.includeMetaField() &&
+          _bucketUnpacker.behavior() == BucketUnpacker::Behavior::kExclude && spec.metaField)) &&
+        std::find(spec.computedMetaProjFields.cbegin(),
+                  spec.computedMetaProjFields.cend(),
+                  *spec.metaField) == spec.computedMetaProjFields.cend())
+        fields.emplace_back(*spec.metaField);
+
+    out.addField(behavior, Value{std::move(fields)});
     out.addField(timeseries::kTimeFieldName, Value{spec.timeField});
     if (spec.metaField) {
         out.addField(timeseries::kMetaFieldName, Value{*spec.metaField});
     }
     out.addField("bucketMaxSpanSeconds", Value{_bucketMaxSpanSeconds});
 
+    if (!spec.computedMetaProjFields.empty())
+        out.addField("computedMetaProjFields", Value{[&] {
+                         std::vector<Value> compFields;
+                         std::transform(spec.computedMetaProjFields.cbegin(),
+                                        spec.computedMetaProjFields.cend(),
+                                        std::back_inserter(compFields),
+                                        [](auto&& projString) { return Value{projString}; });
+                         return compFields;
+                     }()});
+
     if (!explain) {
         array.push_back(Value(DOC(getSourceName() << out.freeze())));
         if (_sampleSize) {
diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h
index c7dc7ccb0a4..171547cd4d8 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h
@@ -30,6 +30,7 @@
 #pragma once
 
 #include <set>
+#include <vector>
 
 #include "mongo/db/exec/bucket_unpacker.h"
 #include "mongo/db/pipeline/document_source.h"
diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/internalize_project_test.cpp b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/internalize_project_test.cpp
index 8151a279242..5366e6789ce 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/internalize_project_test.cpp
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/internalize_project_test.cpp
@@ -157,8 +157,8 @@ TEST_F(InternalUnpackBucketInternalizeProjectTest,
 
     std::vector<Value> serializedArray;
     unpack->serializeToArray(serializedArray);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id'], timeField: 'time', "
-                               "metaField: 'meta', bucketMaxSpanSeconds: 3600}}"),
+    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'meta'], timeField: "
+                               "'time', metaField: 'meta', bucketMaxSpanSeconds: 3600}}"),
                       serializedArray[0].getDocument().toBson());
     ASSERT_TRUE(unpack->includeMetaField());
     ASSERT_FALSE(unpack->includeTimeField());
@@ -177,7 +177,7 @@ TEST_F(InternalUnpackBucketInternalizeProjectTest,
 
     std::vector<Value> serializedArray;
     unpack->serializeToArray(serializedArray);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { exclude: [], timeField: 'time', "
+    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { exclude: ['myMeta'], timeField: 'time', "
                                "metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
                       serializedArray[0].getDocument().toBson());
     ASSERT_FALSE(unpack->includeMetaField());
diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/optimize_pipeline_test.cpp b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/optimize_pipeline_test.cpp
index 6f0978011c1..17077b428ed 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/optimize_pipeline_test.cpp
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/optimize_pipeline_test.cpp
@@ -346,9 +346,10 @@ TEST_F(OptimizePipeline, ProjectThenMixedMatchPushedDown) {
         fromjson(
             "{$match: {$and: [{meta: {$eq: 'abc'}}, {'control.min.a': {$_internalExprLte: 4}}]}}"),
         stages[0].getDocument().toBson());
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'a', 'x'], timeField: "
-                               "'time', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      stages[1].getDocument().toBson());
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { include: ['_id', 'a', 'x', 'myMeta'], timeField: "
+                 "'time', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
+        stages[1].getDocument().toBson());
     ASSERT_BSONOBJ_EQ(fromjson("{$match: {a: {$lte: 4}}}"), stages[2].getDocument().toBson());
     const UnorderedFieldsBSONObjComparator kComparator;
     ASSERT_EQ(
@@ -401,9 +402,10 @@ TEST_F(OptimizePipeline, ComputedProjectThenMetaMatchPushedDown) {
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$match: {meta: {$gte: 'abc'}}}"), serialized[0]);
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {y: '$meta'}}"), serialized[1]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'y'], timeField: "
-                               "'time', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[2]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { include: ['_id', 'y'], timeField: 'time', metaField: "
+                 "'myMeta', bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['y']}}"),
+        serialized[2]);
 }
 
 TEST_F(OptimizePipeline, ComputedProjectThenMetaMatchNotPushedDown) {
@@ -423,11 +425,13 @@ TEST_F(OptimizePipeline, ComputedProjectThenMetaMatchNotPushedDown) {
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {myMeta: {$sum: ['$meta.a', '$meta.b']}}}"),
                       serialized[0]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id'], timeField: "
-                               "'time', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[1]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson(
+            "{$_internalUnpackBucket: { include: ['_id', 'myMeta'], timeField: 'time', metaField: "
+            "'myMeta', bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['myMeta']}}"),
+        serialized[1]);
     ASSERT_BSONOBJ_EQ(fromjson("{$match: {myMeta: {$gte: 'abc'}}}"), serialized[2]);
-}
+}  // namespace
 
 TEST_F(OptimizePipeline, ComputedProjectThenMatchNotPushedDown) {
     auto pipeline = Pipeline::parse(
@@ -445,9 +449,10 @@ TEST_F(OptimizePipeline, ComputedProjectThenMatchNotPushedDown) {
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {y: {$sum: ['$meta.a', '$meta.b']}}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'y'], timeField: "
-                               "'time', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[1]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { include: ['_id', 'y'], timeField: 'time', metaField: "
+                 "'myMeta', bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['y']}}"),
+        serialized[1]);
     ASSERT_BSONOBJ_EQ(fromjson("{$match: {y: {$gt: 'abc'}}}"), serialized[2]);
 }
 
@@ -466,9 +471,10 @@ TEST_F(OptimizePipeline, MetaSortThenProjectPushedDown) {
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(2u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$sort: {meta: -1}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'x'], timeField: "
-                               "'time', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[1]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { include: ['_id', 'x', 'myMeta'], timeField: 'time', "
+                 "metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
+        serialized[1]);
 }
 
 TEST_F(OptimizePipeline, ProjectThenMetaSortPushedDown) {
@@ -486,9 +492,10 @@ TEST_F(OptimizePipeline, ProjectThenMetaSortPushedDown) {
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(2u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$sort: {meta: -1}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'x'], timeField: "
-                               "'time', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[1]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { include: ['_id', 'x', 'myMeta'], timeField: 'time', "
+                 "metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
+        serialized[1]);
 }
 
 TEST_F(OptimizePipeline, ComputedProjectThenSortPushedDown) {
@@ -507,9 +514,11 @@ TEST_F(OptimizePipeline, ComputedProjectThenSortPushedDown) {
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {myMeta: '$meta.a'}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id'], timeField: 'time', "
-                               "metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[1]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson(
+            "{$_internalUnpackBucket: { include: ['_id', 'myMeta'], timeField: 'time', metaField: "
+            "'myMeta', bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['myMeta']}}"),
+        serialized[1]);
     ASSERT_BSONOBJ_EQ(fromjson("{$sort: {myMeta: 1}}"), serialized[2]);
 }
 
@@ -552,9 +561,11 @@ TEST_F(OptimizePipeline, ComputedProjectThenProjectPushDown) {
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {myMeta: '$meta.a'}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id'], timeField: 'time', "
-                               "metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[1]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson(
+            "{$_internalUnpackBucket: { include: ['_id', 'myMeta'], timeField: 'time', metaField: "
+            "'myMeta', bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['myMeta']}}"),
+        serialized[1]);
     ASSERT_BSONOBJ_EQ(fromjson("{$project: {myMeta: false, _id: true}}"), serialized[2]);
 }
 
@@ -573,9 +584,10 @@ TEST_F(OptimizePipeline, AddFieldsThenSortPushedDown) {
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {myMeta: '$meta.a'}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { exclude: [], timeField: 'time', "
-                               "metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[1]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { exclude: [], timeField: 'time', metaField: 'myMeta', "
+                 "bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['myMeta']}}"),
+        serialized[1]);
     ASSERT_BSONOBJ_EQ(fromjson("{$sort: {myMeta: 1}}"), serialized[2]);
 }
 
@@ -595,10 +607,10 @@ TEST_F(OptimizePipeline, PushDownAddFieldsAndInternalizeProjection) {
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(2u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {device: '$meta.a'}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(
-        fromjson("{$_internalUnpackBucket: { include: ['_id', 'device', 'x'], "
-                 "timeField: 'time', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-        serialized[1]);
+    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'device', 'x'], "
+                               "timeField: 'time', metaField: 'myMeta', bucketMaxSpanSeconds: "
+                               "3600, computedMetaProjFields: ['device']}}"),
+                      serialized[1]);
 }
 
 TEST_F(OptimizePipeline, PushDownAddFieldsDoNotInternalizeProjection) {
@@ -619,8 +631,8 @@ TEST_F(OptimizePipeline, PushDownAddFieldsDoNotInternalizeProjection) {
     ASSERT_EQ(4u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {device: '$meta.a'}}"), serialized[0]);
     ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'device', 'x', 'y', "
-                               "'z'], timeField: 'time', "
-                               "metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
+                               "'z'], timeField: 'time', metaField: 'myMeta', "
+                               "bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['device']}}"),
                       serialized[1]);
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {z: {$add : ['$x', '$y']}}}"), serialized[2]);
     const UnorderedFieldsBSONObjComparator kComparator;
@@ -646,10 +658,10 @@ TEST_F(OptimizePipeline, InternalizeProjectAndPushdownAddFields) {
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(2u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {newMeta: '$meta.a'}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(
-        fromjson("{$_internalUnpackBucket: { include: ['_id', 'newMeta', 'x', 'y'], "
-                 "timeField: 'time', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-        serialized[1]);
+    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'newMeta', 'x', 'y', "
+                               "'myMeta'], timeField: 'time', metaField: 'myMeta', "
+                               "bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['newMeta']}}"),
+                      serialized[1]);
 }
 
 TEST_F(OptimizePipeline, PushdownSortAndAddFields) {
@@ -667,9 +679,10 @@ TEST_F(OptimizePipeline, PushdownSortAndAddFields) {
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {newMeta: '$meta.a'}}"), serialized[0]);
     ASSERT_BSONOBJ_EQ(fromjson("{$sort: {meta: -1}}"), serialized[1]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { exclude: [], timeField: 'time', "
-                               "metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[2]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { exclude: [], timeField: 'time', metaField: 'myMeta', "
+                 "bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['newMeta']}}"),
+        serialized[2]);
 }
 
 TEST_F(OptimizePipeline, PushdownMatchAndAddFields) {
@@ -689,9 +702,10 @@ TEST_F(OptimizePipeline, PushdownMatchAndAddFields) {
     ASSERT_EQ(4u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$match: {'meta.a': {$eq: 'abc'}}}"), serialized[0]);
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {newMeta: '$meta.b'}}"), serialized[1]);
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { exclude: [], timeField: 'time', "
-                               "metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[2]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { exclude: [], timeField: 'time', metaField: 'myMeta', "
+                 "bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['newMeta']}}"),
+        serialized[2]);
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {z: {$add : ['$x', '$y']}}}"), serialized[3]);
 }
 }  // namespace
diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/pushdown_computed_meta_projections_test.cpp b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/pushdown_computed_meta_projections_test.cpp
index 47d7de0b8c0..3f34f8cc345 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/pushdown_computed_meta_projections_test.cpp
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/pushdown_computed_meta_projections_test.cpp
@@ -59,7 +59,10 @@ TEST_F(InternalUnpackBucketPushdownProjectionsTest,
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(2u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {newMeta: {$toUpper: ['$meta']}}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(unpackSpecObj, serialized[1]);
+    auto extraField = fromjson("{computedMetaProjFields: ['newMeta']}");
+    ASSERT_BSONOBJ_EQ(BSON("$_internalUnpackBucket" << unpackSpecObj.firstElement().Obj().addField(
+                               extraField.firstElement())),
+                      serialized[1]);
 }
 
 TEST_F(InternalUnpackBucketPushdownProjectionsTest, OptimizeAddFieldsWithMetaProjectionDocument) {
@@ -79,7 +82,10 @@ TEST_F(InternalUnpackBucketPushdownProjectionsTest, OptimizeAddFieldsWithMetaPro
     ASSERT_EQ(2u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {newMeta: {$concat: ['$meta.a', '$meta.b']}}}"),
                       serialized[0]);
-    ASSERT_BSONOBJ_EQ(unpackSpecObj, serialized[1]);
+    auto extraField = fromjson("{computedMetaProjFields: ['newMeta']}");
+    ASSERT_BSONOBJ_EQ(BSON("$_internalUnpackBucket" << unpackSpecObj.firstElement().Obj().addField(
+                               extraField.firstElement())),
+                      serialized[1]);
 }
 
 TEST_F(InternalUnpackBucketPushdownProjectionsTest, OptimizeAddFieldsWith2MetaProjections) {
@@ -99,7 +105,10 @@ TEST_F(InternalUnpackBucketPushdownProjectionsTest, OptimizeAddFieldsWith2MetaPr
     ASSERT_EQ(2u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {device: '$meta.a', deviceType: '$meta.b'}}"),
                       serialized[0]);
-    ASSERT_BSONOBJ_EQ(unpackSpecObj, serialized[1]);
+    auto extraField = fromjson("{computedMetaProjFields: ['device', 'deviceType']}");
+    ASSERT_BSONOBJ_EQ(BSON("$_internalUnpackBucket" << unpackSpecObj.firstElement().Obj().addField(
+                               extraField.firstElement())),
+                      serialized[1]);
 }
 
 TEST_F(InternalUnpackBucketPushdownProjectionsTest, SplitAddFieldsWithMixedProjectionFields) {
@@ -118,7 +127,10 @@ TEST_F(InternalUnpackBucketPushdownProjectionsTest, SplitAddFieldsWithMixedProje
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {device: '$meta.a'}}"), serialized[0]);
-    ASSERT_BSONOBJ_EQ(unpackSpecObj, serialized[1]);
+    auto extraField = fromjson("{computedMetaProjFields: ['device']}");
+    ASSERT_BSONOBJ_EQ(BSON("$_internalUnpackBucket" << unpackSpecObj.firstElement().Obj().addField(
+                               extraField.firstElement())),
+                      serialized[1]);
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: {temp: {$add: ['$temperature', '$offset']}}}"),
                       serialized[2]);
 }
@@ -234,6 +246,10 @@ TEST_F(InternalUnpackBucketPushdownProjectionsTest,
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: { device: '$meta.a'}}"), serialized[0]);
+    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { exclude: [], timeField: 'time', "
+                               "metaField: 'myMeta', bucketMaxSpanSeconds: 3600, "
+                               "computedMetaProjFields: ['device']}}"),
+                      serialized[1]);
     ASSERT_BSONOBJ_EQ(fromjson("{$project: {_id: true, device: true}}"), serialized[2]);
 }
 
@@ -255,6 +271,10 @@ TEST_F(InternalUnpackBucketPushdownProjectionsTest,
     auto serialized = pipeline->serializeToBson();
     ASSERT_EQ(3u, serialized.size());
     ASSERT_BSONOBJ_EQ(fromjson("{$addFields: { device: '$meta.a'}}"), serialized[0]);
+    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { exclude: [], timeField: 'time', "
+                               "metaField: 'myMeta', bucketMaxSpanSeconds: 3600, "
+                               "computedMetaProjFields: ['device']}}"),
+                      serialized[1]);
     ASSERT_BSONOBJ_EQ(
         fromjson("{$project: {_id: true, x: true, y : {z: true}, device: '$device'}}"),
         serialized[2]);
diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/sample_reorder_test.cpp b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/sample_reorder_test.cpp
index b1f1d3d30d4..0b26fce8604 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/sample_reorder_test.cpp
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/sample_reorder_test.cpp
@@ -71,9 +71,10 @@ TEST_F(InternalUnpackBucketSampleReorderTest, SampleThenComputedProject) {
     auto serialized = pipeline->serializeToBson();
 
     ASSERT_EQ(3, serialized.size());
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'temp'], timeField: "
-                               "'foo', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[0]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { include: ['_id', 'temp', 'myMeta'], "
+                 "timeField: 'foo', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
+        serialized[0]);
     ASSERT_BSONOBJ_EQ(sampleSpec, serialized[1]);
     const UnorderedFieldsBSONObjComparator kComparator;
     ASSERT_EQ(kComparator.compare(projectSpec, serialized[2]), 0);
@@ -114,9 +115,10 @@ TEST_F(InternalUnpackBucketSampleReorderTest, ComputedProjectThenSample) {
     auto serialized = pipeline->serializeToBson();
 
     ASSERT_EQ(3, serialized.size());
-    ASSERT_BSONOBJ_EQ(fromjson("{$_internalUnpackBucket: { include: ['_id', 'temp'], timeField: "
-                               "'foo', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
-                      serialized[0]);
+    ASSERT_BSONOBJ_EQ(
+        fromjson("{$_internalUnpackBucket: { include: ['_id', 'temp', 'myMeta'], timeField: "
+                 "'foo', metaField: 'myMeta', bucketMaxSpanSeconds: 3600}}"),
+        serialized[0]);
     ASSERT_BSONOBJ_EQ(sampleSpec, serialized[1]);
     const UnorderedFieldsBSONObjComparator kComparator;
     ASSERT_EQ(kComparator.compare(projectSpec, serialized[2]), 0);
diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/unpack_bucket_exec_test.cpp b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/unpack_bucket_exec_test.cpp
index 587ad434e19..126d4d57e48 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/unpack_bucket_exec_test.cpp
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket_test/unpack_bucket_exec_test.cpp
@@ -824,5 +824,38 @@ TEST_F(InternalUnpackBucketExecTest, ParserRejectsBothIncludeAndExcludeParameter
         AssertionException,
         5408000);
 }
+
+TEST_F(InternalUnpackBucketExecTest, ParserRoundtripsIncludeMeta) {
+    auto bson = fromjson(
+        "{$_internalUnpackBucket: {include: ['steve', 'meta'], timeField: 'time', metaField: "
+        "'meta', bucketMaxSpanSeconds: 3600}}");
+    auto array = std::vector<Value>{};
+    DocumentSourceInternalUnpackBucket::createFromBson(bson.firstElement(), getExpCtx())
+        ->serializeToArray(array);
+    ASSERT_BSONOBJ_EQ(array[0].getDocument().toBson(), bson);
+}
+
+TEST_F(InternalUnpackBucketExecTest, ParserRoundtripsComputedMetaProjFields) {
+    auto bson = fromjson(
+        "{$_internalUnpackBucket: {exclude: [], timeField: 'time', metaField: 'meta', "
+        "bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['a', 'b', 'c']}}");
+    auto array = std::vector<Value>{};
+    DocumentSourceInternalUnpackBucket::createFromBson(bson.firstElement(), getExpCtx())
+        ->serializeToArray(array);
+    ASSERT_BSONOBJ_EQ(array[0].getDocument().toBson(), bson);
+}
+
+TEST_F(InternalUnpackBucketExecTest, ParserRoundtripsComputedMetaProjFieldOverridingMeta) {
+    auto bson = fromjson(
+        "{$_internalUnpackBucket: {exclude: [], timeField: 'time', metaField: 'meta', "
+        "bucketMaxSpanSeconds: 3600, computedMetaProjFields: ['meta']}}");
+    auto unpackBucket =
+        DocumentSourceInternalUnpackBucket::createFromBson(bson.firstElement(), getExpCtx());
+    ASSERT_FALSE(
+        static_cast<DocumentSourceInternalUnpackBucket&>(*unpackBucket).includeMetaField());
+    auto array = std::vector<Value>{};
+    unpackBucket->serializeToArray(array);
+    ASSERT_BSONOBJ_EQ(array[0].getDocument().toBson(), bson);
+}
 }  // namespace
 }  // namespace mongo