Revert "SERVER-61158 add unique to collMod index request"

This reverts commit a94046f398f652564813c90cae8c9e419b1f0f6b.

15 files changed, 73 insertions, 195 deletions

diff --git a/jstests/core/collmod_convert_to_unique.js b/jstests/core/collmod_convert_to_unique.js
deleted file mode 100644
index a7b85450164..00000000000
--- a/jstests/core/collmod_convert_to_unique.js
+++ /dev/null
@@ -1,78 +0,0 @@
-/**
- * Basic js tests for the collMod command converting regular indexes to unique indexes.
- *
- * @tags: [
- *  # Cannot implicitly shard accessed collections because of collection existing when none
- *  # expected.
- *  assumes_no_implicit_collection_creation_after_drop,  # common tag in collMod tests.
- *  requires_fcv_42,
- *  requires_non_retryable_commands, # common tag in collMod tests.
- * ]
- */
-
-(function() {
-'use strict';
-
-const collModIndexUniqueEnabled =
-    assert.commandWorked(db.getMongo().adminCommand({getParameter: 1, collModIndexUnique: 1}))
-        .collModIndexUnique.value;
-
-if (!collModIndexUniqueEnabled) {
-    jsTestLog('Skipping test because the collMod unique index feature flag is disabled.');
-    return;
-}
-
-const collName = 'collmod_convert_to_unique';
-const coll = db.getCollection(collName);
-coll.drop();
-assert.commandWorked(db.createCollection(collName));
-
-function countUnique(key) {
-    const all = coll.getIndexes().filter(function(z) {
-        return z.unique && friendlyEqual(z.key, key);
-    });
-    return all.length;
-}
-
-// Creates a regular index and use collMod to convert it to a unique index.
-assert.commandWorked(coll.createIndex({a: 1}));
-
-// Tries to modify with a string 'unique' value.
-assert.commandFailedWithCode(
-    db.runCommand({collMod: collName, index: {keyPattern: {a: 1}, unique: '100'}}),
-    ErrorCodes.TypeMismatch);
-
-// Tries to modify with a false 'unique' value.
-assert.commandFailedWithCode(db.runCommand({
-    collMod: collName,
-    index: {keyPattern: {a: 1}, unique: false},
-}),
-                             ErrorCodes.BadValue);
-
-assert.commandWorked(coll.insert({_id: 1, a: 100}));
-assert.commandWorked(coll.insert({_id: 2, a: 100}));
-assert.commandWorked(coll.remove({_id: 2}));
-
-// Successfully converts to a unique index.
-const result = assert.commandWorked(
-    db.runCommand({collMod: collName, index: {keyPattern: {a: 1}, unique: true}}));
-
-// New index state should be reflected in 'unique_new' field in collMod response.
-const assertUniqueNew = function(result) {
-    assert(result.hasOwnProperty('unique_new'), tojson(result));
-    assert(result.unique_new, tojson(result));
-};
-if (db.getMongo().isMongos()) {
-    // Check the first shard's result from mongos.
-    assert(result.hasOwnProperty('raw'), tojson(result));
-    assertUniqueNew(Object.values(result.raw)[0]);
-} else {
-    assertUniqueNew(result);
-}
-
-// Look up index details in listIndexes output.
-assert.eq(countUnique({a: 1}), 0, 'index should not be unique yet: ' + tojson(coll.getIndexes()));
-
-// Test uniqueness constraint.
-assert.commandWorked(coll.insert({_id: 100, a: 100}));
-})();
\ No newline at end of file
diff --git a/src/mongo/db/auth/auth_op_observer.cpp b/src/mongo/db/auth/auth_op_observer.cpp
index e059a08ff26..378c3052645 100644
--- a/src/mongo/db/auth/auth_op_observer.cpp
+++ b/src/mongo/db/auth/auth_op_observer.cpp
@@ -111,11 +111,11 @@ void AuthOpObserver::onCollMod(OperationContext* opCtx,
                                OptionalCollectionUUID uuid,
                                const BSONObj& collModCmd,
                                const CollectionOptions& oldCollOptions,
-                               boost::optional<IndexCollModInfo> indexInfo) {
+                               boost::optional<TTLCollModInfo> ttlInfo) {
     const auto cmdNss = nss.getCommandNS();
 
     // Create the 'o' field object.
-    const auto cmdObj = makeCollModCmdObj(collModCmd, oldCollOptions, indexInfo);
+    const auto cmdObj = makeCollModCmdObj(collModCmd, oldCollOptions, ttlInfo);
 
     AuthorizationManager::get(opCtx->getServiceContext())
         ->logOp(opCtx, "c", cmdNss, cmdObj, nullptr);
diff --git a/src/mongo/db/auth/auth_op_observer.h b/src/mongo/db/auth/auth_op_observer.h
index e68929b5461..d5c5ec8f85b 100644
--- a/src/mongo/db/auth/auth_op_observer.h
+++ b/src/mongo/db/auth/auth_op_observer.h
@@ -109,7 +109,7 @@ public:
                    OptionalCollectionUUID uuid,
                    const BSONObj& collModCmd,
                    const CollectionOptions& oldCollOptions,
-                   boost::optional<IndexCollModInfo> indexInfo) final;
+                   boost::optional<TTLCollModInfo> ttlInfo) final;
 
     void onDropDatabase(OperationContext* opCtx, const std::string& dbName) final;
 
diff --git a/src/mongo/db/catalog/coll_mod.cpp b/src/mongo/db/catalog/coll_mod.cpp
index 040cc631a97..582d073e664 100644
--- a/src/mongo/db/catalog/coll_mod.cpp
+++ b/src/mongo/db/catalog/coll_mod.cpp
@@ -53,7 +53,6 @@
 #include "mongo/db/service_context.h"
 #include "mongo/db/storage/durable_catalog.h"
 #include "mongo/db/storage/recovery_unit.h"
-#include "mongo/db/storage/storage_parameters_gen.h"
 #include "mongo/db/views/view_catalog.h"
 #include "mongo/util/fail_point_service.h"
 #include "mongo/util/log.h"
@@ -68,7 +67,6 @@ MONGO_FAIL_POINT_DEFINE(assertAfterIndexUpdate);
 struct CollModRequest {
     const IndexDescriptor* idx = nullptr;
     BSONElement indexExpireAfterSeconds = {};
-    BSONElement indexUnique = {};
     BSONElement viewPipeLine = {};
     std::string viewOn = {};
     boost::optional<BSONObj> collValidator;
@@ -124,24 +122,13 @@ StatusWith<CollModRequest> parseCollModRequest(OperationContext* opCtx,
             }
 
             cmr.indexExpireAfterSeconds = indexObj["expireAfterSeconds"];
-            cmr.indexUnique = indexObj["unique"];
-
-            if (cmr.indexUnique) {
-                uassert(ErrorCodes::InvalidOptions,
-                        "collMod does not support converting an index to unique",
-                        gCollModIndexUnique);
-            }
-
-            if (!cmr.indexExpireAfterSeconds && !cmr.indexUnique) {
-                return Status(ErrorCodes::InvalidOptions, "no expireAfterSeconds or unique field");
+            if (cmr.indexExpireAfterSeconds.eoo()) {
+                return Status(ErrorCodes::InvalidOptions, "no expireAfterSeconds field");
             }
-            if (cmr.indexExpireAfterSeconds && !cmr.indexExpireAfterSeconds.isNumber()) {
+            if (!cmr.indexExpireAfterSeconds.isNumber()) {
                 return Status(ErrorCodes::InvalidOptions,
                               "expireAfterSeconds field must be a number");
             }
-            if (cmr.indexUnique && !cmr.indexUnique.isBoolean()) {
-                return Status(ErrorCodes::InvalidOptions, "unique field must be a boolean");
-            }
 
             if (!indexName.empty()) {
                 cmr.idx = coll->getIndexCatalog()->findIndexByName(opCtx, indexName);
@@ -171,20 +158,13 @@ StatusWith<CollModRequest> parseCollModRequest(OperationContext* opCtx,
                 cmr.idx = indexes[0];
             }
 
-            if (cmr.indexExpireAfterSeconds) {
-                BSONElement oldExpireSecs = cmr.idx->infoObj().getField("expireAfterSeconds");
-                if (oldExpireSecs.eoo()) {
-                    return Status(ErrorCodes::InvalidOptions,
-                                  "no expireAfterSeconds field to update");
-                }
-                if (!oldExpireSecs.isNumber()) {
-                    return Status(ErrorCodes::InvalidOptions,
-                                  "existing expireAfterSeconds field is not a number");
-                }
+            BSONElement oldExpireSecs = cmr.idx->infoObj().getField("expireAfterSeconds");
+            if (oldExpireSecs.eoo()) {
+                return Status(ErrorCodes::InvalidOptions, "no expireAfterSeconds field to update");
             }
-
-            if (cmr.indexUnique && !cmr.indexUnique.trueValue()) {
-                return Status(ErrorCodes::BadValue, "Cannot make index non-unique");
+            if (!oldExpireSecs.isNumber()) {
+                return Status(ErrorCodes::InvalidOptions,
+                              "existing expireAfterSeconds field is not a number");
             }
 
         } else if (fieldName == "validator" && !isView) {
@@ -355,52 +335,36 @@ Status _collModInternal(OperationContext* opCtx,
 
     CollectionOptions oldCollOptions = DurableCatalog::get(opCtx)->getCollectionOptions(opCtx, nss);
 
-    boost::optional<IndexCollModInfo> indexCollModInfo;
-    BSONElement newExpireSecs = {};
-    BSONElement oldExpireSecs = {};
-    BSONElement newUnique = {};
+    boost::optional<TTLCollModInfo> ttlInfo;
 
     // Handle collMod operation type appropriately.
 
-    if (cmr.idx) {
-        // TTLIndex
-        if (cmr.indexExpireAfterSeconds) {
-            newExpireSecs = cmr.indexExpireAfterSeconds;
-            oldExpireSecs = cmr.idx->infoObj().getField("expireAfterSeconds");
+    // TTLIndex
+    if (!cmr.indexExpireAfterSeconds.eoo()) {
+        BSONElement& newExpireSecs = cmr.indexExpireAfterSeconds;
+        BSONElement oldExpireSecs = cmr.idx->infoObj().getField("expireAfterSeconds");
 
-            if (SimpleBSONElementComparator::kInstance.evaluate(oldExpireSecs != newExpireSecs)) {
-                result->appendAs(oldExpireSecs, "expireAfterSeconds_old");
+        if (SimpleBSONElementComparator::kInstance.evaluate(oldExpireSecs != newExpireSecs)) {
+            result->appendAs(oldExpireSecs, "expireAfterSeconds_old");
 
-                // Change the value of "expireAfterSeconds" on disk.
-                DurableCatalog::get(opCtx)->updateTTLSetting(
-                    opCtx, coll->ns(), cmr.idx->indexName(), newExpireSecs.safeNumberLong());
+            // Change the value of "expireAfterSeconds" on disk.
+            DurableCatalog::get(opCtx)->updateTTLSetting(
+                opCtx, coll->ns(), cmr.idx->indexName(), newExpireSecs.safeNumberLong());
 
-                // Notify the index catalog that the definition of this index changed.
-                cmr.idx = coll->getIndexCatalog()->refreshEntry(opCtx, cmr.idx);
-                result->appendAs(newExpireSecs, "expireAfterSeconds_new");
+            // Notify the index catalog that the definition of this index changed.
+            cmr.idx = coll->getIndexCatalog()->refreshEntry(opCtx, cmr.idx);
+            result->appendAs(newExpireSecs, "expireAfterSeconds_new");
 
-                if (MONGO_FAIL_POINT(assertAfterIndexUpdate)) {
-                    log() << "collMod - assertAfterIndexUpdate fail point enabled.";
-                    uasserted(50970, "trigger rollback after the index update");
-                }
-            }
-        }
-
-        // UniqueIndex
-        if (cmr.indexUnique) {
-            if (!cmr.idx->infoObj().getField("unique").trueValue()) {
-                newUnique = cmr.indexUnique;
-                result->appendAs(newUnique, "unique_new");
+            if (MONGO_FAIL_POINT(assertAfterIndexUpdate)) {
+                log() << "collMod - assertAfterIndexUpdate fail point enabled.";
+                uasserted(50970, "trigger rollback after the index update");
             }
         }
 
-        indexCollModInfo =
-            IndexCollModInfo{!cmr.indexExpireAfterSeconds ? boost::optional<Seconds>()
-                                                          : Seconds(newExpireSecs.safeNumberLong()),
-                             !cmr.indexExpireAfterSeconds ? boost::optional<Seconds>()
-                                                          : Seconds(oldExpireSecs.safeNumberLong()),
-                             !cmr.indexUnique ? boost::optional<bool>() : newUnique.booleanSafe(),
-                             cmr.idx->indexName()};
+        // Save previous TTL index expiration.
+        ttlInfo = TTLCollModInfo{Seconds(newExpireSecs.safeNumberLong()),
+                                 Seconds(oldExpireSecs.safeNumberLong()),
+                                 cmr.idx->indexName()};
     }
 
     if (cmr.collValidator) {
@@ -443,7 +407,7 @@ Status _collModInternal(OperationContext* opCtx,
     // Only observe non-view collMods, as view operations are observed as operations on the
     // system.views collection.
     getGlobalServiceContext()->getOpObserver()->onCollMod(
-        opCtx, nss, coll->uuid(), oplogEntryBuilder.obj(), oldCollOptions, indexCollModInfo);
+        opCtx, nss, coll->uuid(), oplogEntryBuilder.obj(), oldCollOptions, ttlInfo);
 
     wunit.commit();
 
diff --git a/src/mongo/db/free_mon/free_mon_op_observer.h b/src/mongo/db/free_mon/free_mon_op_observer.h
index a3d4e5f45bb..e3e591973fa 100644
--- a/src/mongo/db/free_mon/free_mon_op_observer.h
+++ b/src/mongo/db/free_mon/free_mon_op_observer.h
@@ -109,7 +109,7 @@ public:
                    OptionalCollectionUUID uuid,
                    const BSONObj& collModCmd,
                    const CollectionOptions& oldCollOptions,
-                   boost::optional<IndexCollModInfo> indexInfo) final {}
+                   boost::optional<TTLCollModInfo> ttlInfo) final {}
 
     void onDropDatabase(OperationContext* opCtx, const std::string& dbName) final {}
 
diff --git a/src/mongo/db/op_observer.h b/src/mongo/db/op_observer.h
index e73fcb66171..b5b4a992246 100644
--- a/src/mongo/db/op_observer.h
+++ b/src/mongo/db/op_observer.h
@@ -60,10 +60,9 @@ struct OplogUpdateEntryArgs {
         : updateArgs(std::move(updateArgs)), nss(std::move(nss)), uuid(std::move(uuid)) {}
 };
 
-struct IndexCollModInfo {
-    boost::optional<Seconds> expireAfterSeconds;
-    boost::optional<Seconds> oldExpireAfterSeconds;
-    boost::optional<bool> unique;
+struct TTLCollModInfo {
+    Seconds expireAfterSeconds;
+    Seconds oldExpireAfterSeconds;
     std::string indexName;
 };
 
@@ -180,7 +179,7 @@ public:
      *
      * To facilitate the rollback process, 'oldCollOptions' contains the previous state of all
      * collection options i.e. the state prior to completion of the current collMod command.
-     * 'indexInfo' contains the index name and previous expiration time of a TTL index. The old
+     * 'ttlInfo' contains the index name and previous expiration time of a TTL index. The old
      * collection options will be stored in the 'o2.collectionOptions_old' field, and the old TTL
      * expiration value in the 'o2.expireAfterSeconds_old' field.
      *
@@ -207,7 +206,7 @@ public:
                            OptionalCollectionUUID uuid,
                            const BSONObj& collModCmd,
                            const CollectionOptions& oldCollOptions,
-                           boost::optional<IndexCollModInfo> indexInfo) = 0;
+                           boost::optional<TTLCollModInfo> ttlInfo) = 0;
     virtual void onDropDatabase(OperationContext* opCtx, const std::string& dbName) = 0;
 
     /**
diff --git a/src/mongo/db/op_observer_impl.cpp b/src/mongo/db/op_observer_impl.cpp
index 8643d03649f..4ba2ccf847b 100644
--- a/src/mongo/db/op_observer_impl.cpp
+++ b/src/mongo/db/op_observer_impl.cpp
@@ -791,21 +791,18 @@ void OpObserverImpl::onCollMod(OperationContext* opCtx,
                                OptionalCollectionUUID uuid,
                                const BSONObj& collModCmd,
                                const CollectionOptions& oldCollOptions,
-                               boost::optional<IndexCollModInfo> indexInfo) {
+                               boost::optional<TTLCollModInfo> ttlInfo) {
     const auto cmdNss = nss.getCommandNS();
 
     // Create the 'o' field object.
-    const auto cmdObj = makeCollModCmdObj(collModCmd, oldCollOptions, indexInfo);
+    const auto cmdObj = makeCollModCmdObj(collModCmd, oldCollOptions, ttlInfo);
 
     // Create the 'o2' field object. We save the old collection metadata and TTL expiration.
     BSONObjBuilder o2Builder;
     o2Builder.append("collectionOptions_old", oldCollOptions.toBSON());
-    if (indexInfo) {
-        if (indexInfo->oldExpireAfterSeconds) {
-            auto oldExpireAfterSeconds =
-                durationCount<Seconds>(indexInfo->oldExpireAfterSeconds.get());
-            o2Builder.append("expireAfterSeconds_old", oldExpireAfterSeconds);
-        }
+    if (ttlInfo) {
+        auto oldExpireAfterSeconds = durationCount<Seconds>(ttlInfo->oldExpireAfterSeconds);
+        o2Builder.append("expireAfterSeconds_old", oldExpireAfterSeconds);
     }
 
     const auto o2Obj = o2Builder.done();
diff --git a/src/mongo/db/op_observer_impl.h b/src/mongo/db/op_observer_impl.h
index 6f4ee4a401d..9fb50fda884 100644
--- a/src/mongo/db/op_observer_impl.h
+++ b/src/mongo/db/op_observer_impl.h
@@ -99,7 +99,7 @@ public:
                    OptionalCollectionUUID uuid,
                    const BSONObj& collModCmd,
                    const CollectionOptions& oldCollOptions,
-                   boost::optional<IndexCollModInfo> indexInfo) final;
+                   boost::optional<TTLCollModInfo> ttlInfo) final;
     void onDropDatabase(OperationContext* opCtx, const std::string& dbName) final;
     repl::OpTime onDropCollection(OperationContext* opCtx,
                                   const NamespaceString& collectionName,
diff --git a/src/mongo/db/op_observer_impl_test.cpp b/src/mongo/db/op_observer_impl_test.cpp
index ad809413f1e..acb75e80994 100644
--- a/src/mongo/db/op_observer_impl_test.cpp
+++ b/src/mongo/db/op_observer_impl_test.cpp
@@ -251,16 +251,16 @@ TEST_F(OpObserverTest, CollModWithCollectionOptionsAndTTLInfo) {
     oldCollOpts.validationLevel = "strict";
     oldCollOpts.validationAction = "error";
 
-    IndexCollModInfo indexInfo;
-    indexInfo.expireAfterSeconds = Seconds(10);
-    indexInfo.oldExpireAfterSeconds = Seconds(5);
-    indexInfo.indexName = "name_of_index";
+    TTLCollModInfo ttlInfo;
+    ttlInfo.expireAfterSeconds = Seconds(10);
+    ttlInfo.oldExpireAfterSeconds = Seconds(5);
+    ttlInfo.indexName = "name_of_index";
 
     // Write to the oplog.
     {
         AutoGetCollection autoColl(opCtx.get(), nss, MODE_IX, MODE_X);
         WriteUnitOfWork wunit(opCtx.get());
-        opObserver.onCollMod(opCtx.get(), nss, uuid, collModCmd, oldCollOpts, indexInfo);
+        opObserver.onCollMod(opCtx.get(), nss, uuid, collModCmd, oldCollOpts, ttlInfo);
         wunit.commit();
     }
 
@@ -268,14 +268,14 @@ TEST_F(OpObserverTest, CollModWithCollectionOptionsAndTTLInfo) {
 
     // Ensure that collMod fields were properly added to the oplog entry.
     auto o = oplogEntry.getObjectField("o");
-    auto oExpected = BSON(
-        "collMod" << nss.coll() << "validationLevel"
-                  << "off"
-                  << "validationAction"
-                  << "warn"
-                  << "index"
-                  << BSON("name" << indexInfo.indexName << "expireAfterSeconds"
-                                 << durationCount<Seconds>(indexInfo.expireAfterSeconds.get())));
+    auto oExpected =
+        BSON("collMod" << nss.coll() << "validationLevel"
+                       << "off"
+                       << "validationAction"
+                       << "warn"
+                       << "index"
+                       << BSON("name" << ttlInfo.indexName << "expireAfterSeconds"
+                                      << durationCount<Seconds>(ttlInfo.expireAfterSeconds)));
     ASSERT_BSONOBJ_EQ(oExpected, o);
 
     // Ensure that the old collection metadata was saved.
@@ -284,8 +284,7 @@ TEST_F(OpObserverTest, CollModWithCollectionOptionsAndTTLInfo) {
         BSON("collectionOptions_old"
              << BSON("validationLevel" << oldCollOpts.validationLevel << "validationAction"
                                        << oldCollOpts.validationAction)
-             << "expireAfterSeconds_old"
-             << durationCount<Seconds>(indexInfo.oldExpireAfterSeconds.get()));
+             << "expireAfterSeconds_old" << durationCount<Seconds>(ttlInfo.oldExpireAfterSeconds));
 
     ASSERT_BSONOBJ_EQ(o2Expected, o2);
 }
diff --git a/src/mongo/db/op_observer_noop.h b/src/mongo/db/op_observer_noop.h
index b9aa1b90d2e..f3543e3e1ae 100644
--- a/src/mongo/db/op_observer_noop.h
+++ b/src/mongo/db/op_observer_noop.h
@@ -93,7 +93,7 @@ public:
                    OptionalCollectionUUID uuid,
                    const BSONObj& collModCmd,
                    const CollectionOptions& oldCollOptions,
-                   boost::optional<IndexCollModInfo> indexInfo) override {}
+                   boost::optional<TTLCollModInfo> ttlInfo) override {}
     void onDropDatabase(OperationContext* opCtx, const std::string& dbName) override {}
     repl::OpTime onDropCollection(OperationContext* opCtx,
                                   const NamespaceString& collectionName,
diff --git a/src/mongo/db/op_observer_registry.h b/src/mongo/db/op_observer_registry.h
index 4d4b9fd3896..ba1ef6ba91e 100644
--- a/src/mongo/db/op_observer_registry.h
+++ b/src/mongo/db/op_observer_registry.h
@@ -165,10 +165,10 @@ public:
                    OptionalCollectionUUID uuid,
                    const BSONObj& collModCmd,
                    const CollectionOptions& oldCollOptions,
-                   boost::optional<IndexCollModInfo> indexInfo) override {
+                   boost::optional<TTLCollModInfo> ttlInfo) override {
         ReservedTimes times{opCtx};
         for (auto& o : _observers)
-            o->onCollMod(opCtx, nss, uuid, collModCmd, oldCollOptions, indexInfo);
+            o->onCollMod(opCtx, nss, uuid, collModCmd, oldCollOptions, ttlInfo);
     }
 
     void onDropDatabase(OperationContext* const opCtx, const std::string& dbName) override {
diff --git a/src/mongo/db/op_observer_util.cpp b/src/mongo/db/op_observer_util.cpp
index f7512cc21a7..b1bc7074915 100644
--- a/src/mongo/db/op_observer_util.cpp
+++ b/src/mongo/db/op_observer_util.cpp
@@ -42,24 +42,21 @@ namespace mongo {
  */
 BSONObj makeCollModCmdObj(const BSONObj& collModCmd,
                           const CollectionOptions& oldCollOptions,
-                          boost::optional<IndexCollModInfo> indexInfo) {
+                          boost::optional<TTLCollModInfo> ttlInfo) {
     BSONObjBuilder cmdObjBuilder;
-    std::string indexFieldName = "index";
+    std::string ttlIndexFieldName = "index";
 
     // Add all fields from the original collMod command.
     for (auto elem : collModCmd) {
         // We normalize all TTL collMod oplog entry objects to use the index name, even if the
         // command used an index key pattern.
-        if (elem.fieldNameStringData() == indexFieldName && indexInfo) {
-            BSONObjBuilder indexObjBuilder;
-            indexObjBuilder.append("name", indexInfo->indexName);
-            if (indexInfo->expireAfterSeconds)
-                indexObjBuilder.append("expireAfterSeconds",
-                                       durationCount<Seconds>(indexInfo->expireAfterSeconds.get()));
-            if (indexInfo->unique)
-                indexObjBuilder.append("unique", indexInfo->unique.get());
+        if (elem.fieldNameStringData() == ttlIndexFieldName && ttlInfo) {
+            BSONObjBuilder ttlIndexObjBuilder;
+            ttlIndexObjBuilder.append("name", ttlInfo->indexName);
+            ttlIndexObjBuilder.append("expireAfterSeconds",
+                                      durationCount<Seconds>(ttlInfo->expireAfterSeconds));
 
-            cmdObjBuilder.append(indexFieldName, indexObjBuilder.obj());
+            cmdObjBuilder.append(ttlIndexFieldName, ttlIndexObjBuilder.obj());
         } else {
             cmdObjBuilder.append(elem);
         }
diff --git a/src/mongo/db/op_observer_util.h b/src/mongo/db/op_observer_util.h
index 568c05e2fc7..7e60c66cca8 100644
--- a/src/mongo/db/op_observer_util.h
+++ b/src/mongo/db/op_observer_util.h
@@ -41,5 +41,5 @@ BSONObj makeCreateCollCmdObj(const NamespaceString& collectionName,
 
 BSONObj makeCollModCmdObj(const BSONObj& collModCmd,
                           const CollectionOptions& oldCollOptions,
-                          boost::optional<IndexCollModInfo> indexInfo);
+                          boost::optional<TTLCollModInfo> ttlInfo);
 }  // namespace mongo
diff --git a/src/mongo/db/s/config_server_op_observer.h b/src/mongo/db/s/config_server_op_observer.h
index 60e50c2f719..93d4ef813d2 100644
--- a/src/mongo/db/s/config_server_op_observer.h
+++ b/src/mongo/db/s/config_server_op_observer.h
@@ -109,7 +109,7 @@ public:
                    OptionalCollectionUUID uuid,
                    const BSONObj& collModCmd,
                    const CollectionOptions& oldCollOptions,
-                   boost::optional<IndexCollModInfo> indexInfo) override {}
+                   boost::optional<TTLCollModInfo> ttlInfo) override {}
 
     void onDropDatabase(OperationContext* opCtx, const std::string& dbName) override {}
 
diff --git a/src/mongo/db/s/shard_server_op_observer.h b/src/mongo/db/s/shard_server_op_observer.h
index e88f2b1c8ee..52c35c5f1ce 100644
--- a/src/mongo/db/s/shard_server_op_observer.h
+++ b/src/mongo/db/s/shard_server_op_observer.h
@@ -110,7 +110,7 @@ public:
                    OptionalCollectionUUID uuid,
                    const BSONObj& collModCmd,
                    const CollectionOptions& oldCollOptions,
-                   boost::optional<IndexCollModInfo> indexInfo) override {}
+                   boost::optional<TTLCollModInfo> ttlInfo) override {}
 
     void onDropDatabase(OperationContext* opCtx, const std::string& dbName) override {}