SERVER-25665 Persist chunk version as part of the active migration document

11 files changed, 155 insertions, 117 deletions

diff --git a/src/mongo/db/s/balancer/balancer.cpp b/src/mongo/db/s/balancer/balancer.cpp
index 1cc7d850ada..d2d6f3cc261 100644
--- a/src/mongo/db/s/balancer/balancer.cpp
+++ b/src/mongo/db/s/balancer/balancer.cpp
@@ -275,11 +275,8 @@ Status Balancer::moveSingleChunk(OperationContext* txn,
         return moveAllowedStatus;
     }
 
-    return _migrationManager.executeManualMigration(txn,
-                                                    MigrateInfo(chunk.getNS(), newShardId, chunk),
-                                                    maxChunkSizeBytes,
-                                                    secondaryThrottle,
-                                                    waitForDelete);
+    return _migrationManager.executeManualMigration(
+        txn, MigrateInfo(newShardId, chunk), maxChunkSizeBytes, secondaryThrottle, waitForDelete);
 }
 
 void Balancer::report(OperationContext* txn, BSONObjBuilder* builder) {
diff --git a/src/mongo/db/s/balancer/balancer_chunk_selection_policy_impl.cpp b/src/mongo/db/s/balancer/balancer_chunk_selection_policy_impl.cpp
index 2dc4f48bddf..ef688f73dab 100644
--- a/src/mongo/db/s/balancer/balancer_chunk_selection_policy_impl.cpp
+++ b/src/mongo/db/s/balancer/balancer_chunk_selection_policy_impl.cpp
@@ -76,6 +76,7 @@ StatusWith<DistributionStatus> createCollectionDistributionStatus(
         const auto& chunkEntry = entry.second;
 
         ChunkType chunk;
+        chunk.setNS(chunkMgr->getns());
         chunk.setMin(chunkEntry->getMin());
         chunk.setMax(chunkEntry->getMax());
         chunk.setJumbo(chunkEntry->isJumbo());
diff --git a/src/mongo/db/s/balancer/balancer_policy.cpp b/src/mongo/db/s/balancer/balancer_policy.cpp
index 5b53cfc0320..ea8365f6524 100644
--- a/src/mongo/db/s/balancer/balancer_policy.cpp
+++ b/src/mongo/db/s/balancer/balancer_policy.cpp
@@ -143,7 +143,8 @@ Status DistributionStatus::addRangeToZone(const ZoneRange& range) {
         }
     }
 
-    _zoneRanges[range.max.getOwned()] = range;
+    // This must be a new entry
+    _zoneRanges.emplace(range.max.getOwned(), range);
     _allTags.insert(range.zone);
     return Status::OK();
 }
@@ -337,7 +338,7 @@ vector<MigrateInfo> BalancerPolicy::balance(const ShardStatisticsVector& shardSt
                 }
 
                 invariant(to != stat.shardId);
-                migrations.emplace_back(distribution.nss().ns(), to, chunk);
+                migrations.emplace_back(to, chunk);
                 invariant(usedShards.insert(stat.shardId).second);
                 invariant(usedShards.insert(to).second);
                 break;
@@ -384,7 +385,7 @@ vector<MigrateInfo> BalancerPolicy::balance(const ShardStatisticsVector& shardSt
                 }
 
                 invariant(to != stat.shardId);
-                migrations.emplace_back(distribution.nss().ns(), to, chunk);
+                migrations.emplace_back(to, chunk);
                 invariant(usedShards.insert(stat.shardId).second);
                 invariant(usedShards.insert(to).second);
                 break;
@@ -421,7 +422,7 @@ boost::optional<MigrateInfo> BalancerPolicy::balanceSingleChunk(
         return boost::optional<MigrateInfo>();
     }
 
-    return MigrateInfo(distribution.nss().ns(), newShardId, chunk);
+    return MigrateInfo(newShardId, chunk);
 }
 
 bool BalancerPolicy::_singleZoneBalance(const ShardStatisticsVector& shardStats,
@@ -500,7 +501,7 @@ bool BalancerPolicy::_singleZoneBalance(const ShardStatisticsVector& shardStats,
             continue;
         }
 
-        migrations->emplace_back(distribution.nss().ns(), to, chunk);
+        migrations->emplace_back(to, chunk);
         invariant(usedShards->insert(chunk.getShard()).second);
         invariant(usedShards->insert(to).second);
         return true;
@@ -515,10 +516,26 @@ bool BalancerPolicy::_singleZoneBalance(const ShardStatisticsVector& shardStats,
     return false;
 }
 
+ZoneRange::ZoneRange(const BSONObj& a_min, const BSONObj& a_max, const std::string& _zone)
+    : min(a_min.getOwned()), max(a_max.getOwned()), zone(_zone) {}
+
 string ZoneRange::toString() const {
     return str::stream() << min << " -->> " << max << "  on  " << zone;
 }
 
+MigrateInfo::MigrateInfo(const ShardId& a_to, const ChunkType& a_chunk) {
+    invariantOK(a_chunk.validate());
+    invariant(a_to.isValid());
+
+    to = a_to;
+
+    ns = a_chunk.getNS();
+    from = a_chunk.getShard();
+    minKey = a_chunk.getMin();
+    maxKey = a_chunk.getMax();
+    version = a_chunk.getVersion();
+}
+
 std::string MigrateInfo::getName() const {
     return ChunkType::genID(ns, minKey);
 }
diff --git a/src/mongo/db/s/balancer/balancer_policy.h b/src/mongo/db/s/balancer/balancer_policy.h
index c1438ba995e..c08aee77ceb 100644
--- a/src/mongo/db/s/balancer/balancer_policy.h
+++ b/src/mongo/db/s/balancer/balancer_policy.h
@@ -37,14 +37,8 @@
 
 namespace mongo {
 
-class ChunkManager;
-class OperationContext;
-
 struct ZoneRange {
-    ZoneRange() = default;
-
-    ZoneRange(const BSONObj& a_min, const BSONObj& a_max, const std::string& _zone)
-        : min(a_min.getOwned()), max(a_max.getOwned()), zone(_zone) {}
+    ZoneRange(const BSONObj& a_min, const BSONObj& a_max, const std::string& _zone);
 
     std::string toString() const;
 
@@ -54,21 +48,10 @@ struct ZoneRange {
 };
 
 struct MigrateInfo {
-    MigrateInfo(const std::string& a_ns, const ShardId& a_to, const ChunkType& a_chunk)
-        : ns(a_ns),
-          to(a_to),
-          from(a_chunk.getShard()),
-          minKey(a_chunk.getMin()),
-          maxKey(a_chunk.getMax()) {}
-
-    MigrateInfo(const std::string& a_ns,
-                const ShardId& a_to,
-                const ShardId& a_from,
-                const BSONObj& a_minKey,
-                const BSONObj& a_maxKey)
-        : ns(a_ns), to(a_to), from(a_from), minKey(a_minKey), maxKey(a_maxKey) {}
+    MigrateInfo(const ShardId& a_to, const ChunkType& a_chunk);
 
     std::string getName() const;
+
     std::string toString() const;
 
     std::string ns;
@@ -76,6 +59,7 @@ struct MigrateInfo {
     ShardId from;
     BSONObj minKey;
     BSONObj maxKey;
+    ChunkVersion version;
 };
 
 typedef std::vector<ClusterStatistics::ShardStatistics> ShardStatisticsVector;
diff --git a/src/mongo/db/s/balancer/balancer_policy_test.cpp b/src/mongo/db/s/balancer/balancer_policy_test.cpp
index 35da7c7bf7f..86258c723d8 100644
--- a/src/mongo/db/s/balancer/balancer_policy_test.cpp
+++ b/src/mongo/db/s/balancer/balancer_policy_test.cpp
@@ -30,6 +30,7 @@
 
 #include "mongo/platform/basic.h"
 
+#include "mongo/db/keypattern.h"
 #include "mongo/db/s/balancer/balancer_policy.h"
 #include "mongo/platform/random.h"
 #include "mongo/s/catalog/type_chunk.h"
@@ -76,6 +77,10 @@ std::pair<ShardStatisticsVector, ShardToChunksMap> generateCluster(
 
     int64_t currentChunk = 0;
 
+    ChunkVersion chunkVersion(1, 0, OID::gen());
+
+    const KeyPattern shardKeyPattern(BSON("x" << 1));
+
     for (auto it = shardsAndNumChunks.begin(); it != shardsAndNumChunks.end(); it++) {
         ShardStatistics shard = std::move(it->first);
         const size_t numChunks = it->second;
@@ -85,10 +90,16 @@ std::pair<ShardStatisticsVector, ShardToChunksMap> generateCluster(
 
         for (size_t i = 0; i < numChunks; i++, currentChunk++) {
             ChunkType chunk;
-            chunk.setMin(currentChunk == 0 ? kMinBSONKey : BSON("x" << currentChunk));
-            chunk.setMax(currentChunk == totalNumChunks - 1 ? kMaxBSONKey
+
+            chunk.setNS(kNamespace.ns());
+            chunk.setMin(currentChunk == 0 ? shardKeyPattern.globalMin()
+                                           : BSON("x" << currentChunk));
+            chunk.setMax(currentChunk == totalNumChunks - 1 ? shardKeyPattern.globalMax()
                                                             : BSON("x" << currentChunk + 1));
             chunk.setShard(shard.shardId);
+            chunk.setVersion(chunkVersion);
+
+            chunkVersion.incMajor();
 
             chunkMap[shard.shardId].push_back(std::move(chunk));
         }
diff --git a/src/mongo/db/s/balancer/migration_manager_test.cpp b/src/mongo/db/s/balancer/migration_manager_test.cpp
index 87353c5dc4b..41e2f6419d0 100644
--- a/src/mongo/db/s/balancer/migration_manager_test.cpp
+++ b/src/mongo/db/s/balancer/migration_manager_test.cpp
@@ -113,11 +113,7 @@ protected:
     /**
      * Inserts a document into the config.migrations collection as an active migration.
      */
-    void setUpMigration(const std::string& collName,
-                        const BSONObj& minKey,
-                        const BSONObj& maxKey,
-                        const ShardId& toShard,
-                        const ShardId& fromShard);
+    void setUpMigration(const ChunkType& chunk, const ShardId& toShard);
 
     /**
      * Asserts that config.migrations is empty and config.locks contains no locked documents, both
@@ -219,17 +215,15 @@ ChunkType MigrationManagerTest::setUpChunk(const std::string& collName,
     return chunk;
 }
 
-void MigrationManagerTest::setUpMigration(const std::string& collName,
-                                          const BSONObj& minKey,
-                                          const BSONObj& maxKey,
-                                          const ShardId& toShard,
-                                          const ShardId& fromShard) {
+void MigrationManagerTest::setUpMigration(const ChunkType& chunk, const ShardId& toShard) {
     BSONObjBuilder builder;
-    builder.append(MigrationType::ns(), collName);
-    builder.append(MigrationType::min(), minKey);
-    builder.append(MigrationType::max(), maxKey);
+    builder.append(MigrationType::ns(), chunk.getNS());
+    builder.append(MigrationType::min(), chunk.getMin());
+    builder.append(MigrationType::max(), chunk.getMax());
     builder.append(MigrationType::toShard(), toShard.toString());
-    builder.append(MigrationType::fromShard(), fromShard.toString());
+    builder.append(MigrationType::fromShard(), chunk.getShard().toString());
+    chunk.getVersion().appendWithFieldForCommands(&builder, "chunkVersion");
+
     MigrationType migrationType = assertGet(MigrationType::fromBSON(builder.obj()));
     ASSERT_OK(catalogClient()->insertConfigDocument(operationContext(),
                                                     MigrationType::ConfigNS,
@@ -319,8 +313,7 @@ TEST_F(MigrationManagerTest, OneCollectionTwoMigrations) {
         setUpChunk(collName, BSON(kPattern << 49), kKeyPattern.globalMax(), kShardId2, version);
 
     // Going to request that these two chunks get migrated.
-    const std::vector<MigrateInfo> migrationRequests{{chunk1.getNS(), kShardId1, chunk1},
-                                                     {chunk2.getNS(), kShardId3, chunk2}};
+    const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}, {kShardId3, chunk2}};
 
     auto future = launchAsync([this, migrationRequests] {
         Client::initThreadIfNotAlready("Test");
@@ -379,10 +372,10 @@ TEST_F(MigrationManagerTest, TwoCollectionsTwoMigrationsEach) {
         setUpChunk(collName2, BSON(kPattern << 49), kKeyPattern.globalMax(), kShardId2, version2);
 
     // Going to request that these four chunks get migrated.
-    const std::vector<MigrateInfo> migrationRequests{{chunk1coll1.getNS(), kShardId1, chunk1coll1},
-                                                     {chunk2coll1.getNS(), kShardId3, chunk2coll1},
-                                                     {chunk1coll2.getNS(), kShardId1, chunk1coll2},
-                                                     {chunk2coll2.getNS(), kShardId3, chunk2coll2}};
+    const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1coll1},
+                                                     {kShardId3, chunk2coll1},
+                                                     {kShardId1, chunk1coll2},
+                                                     {kShardId3, chunk2coll2}};
 
     auto future = launchAsync([this, migrationRequests] {
         Client::initThreadIfNotAlready("Test");
@@ -437,8 +430,7 @@ TEST_F(MigrationManagerTest, SameCollectionOldShardMigration) {
         setUpChunk(collName, BSON(kPattern << 49), kKeyPattern.globalMax(), kShardId2, version);
 
     // Going to request that these two chunks get migrated.
-    const std::vector<MigrateInfo> migrationRequests{{chunk1.getNS(), kShardId1, chunk1},
-                                                     {chunk2.getNS(), kShardId3, chunk2}};
+    const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}, {kShardId3, chunk2}};
 
     auto future = launchAsync([this, migrationRequests] {
         Client::initThreadIfNotAlready("Test");
@@ -491,7 +483,7 @@ TEST_F(MigrationManagerTest, SameOldShardFailsToAcquireDistributedLockTwice) {
         setUpChunk(collName, kKeyPattern.globalMin(), kKeyPattern.globalMax(), kShardId0, version);
 
     // Going to request that this chunk get migrated.
-    const std::vector<MigrateInfo> migrationRequests{{chunk1.getNS(), kShardId1, chunk1}};
+    const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}};
 
     auto future = launchAsync([this, migrationRequests] {
         Client::initThreadIfNotAlready("Test");
@@ -550,8 +542,7 @@ TEST_F(MigrationManagerTest, SameCollectionTwoOldShardMigrations) {
         setUpChunk(collName, BSON(kPattern << 49), kKeyPattern.globalMax(), kShardId2, version);
 
     // Going to request that these two chunks get migrated.
-    const std::vector<MigrateInfo> migrationRequests{{chunk1.getNS(), kShardId1, chunk1},
-                                                     {chunk2.getNS(), kShardId3, chunk2}};
+    const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}, {kShardId3, chunk2}};
 
     auto future = launchAsync([this, migrationRequests] {
         Client::initThreadIfNotAlready("Test");
@@ -614,8 +605,7 @@ TEST_F(MigrationManagerTest, FailToAcquireDistributedLock) {
         setUpChunk(collName, BSON(kPattern << 49), kKeyPattern.globalMax(), kShardId2, version);
 
     // Going to request that these two chunks get migrated.
-    const std::vector<MigrateInfo> migrationRequests{{chunk1.getNS(), kShardId1, chunk1},
-                                                     {chunk2.getNS(), kShardId3, chunk2}};
+    const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}, {kShardId3, chunk2}};
 
     shardTargeterMock(operationContext(), kShardId0)->setFindHostReturnValue(kShardHost0);
     shardTargeterMock(operationContext(), kShardId2)->setFindHostReturnValue(kShardHost2);
@@ -662,8 +652,7 @@ TEST_F(MigrationManagerTest, SourceShardNotFound) {
         setUpChunk(collName, BSON(kPattern << 49), kKeyPattern.globalMax(), kShardId2, version);
 
     // Going to request that these two chunks get migrated.
-    const std::vector<MigrateInfo> migrationRequests{{chunk1.getNS(), kShardId1, chunk1},
-                                                     {chunk2.getNS(), kShardId3, chunk2}};
+    const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}, {kShardId3, chunk2}};
 
     auto future = launchAsync([this, chunk1, chunk2, migrationRequests] {
         Client::initThreadIfNotAlready("Test");
@@ -708,7 +697,7 @@ TEST_F(MigrationManagerTest, JumboChunkResponseBackwardsCompatibility) {
         setUpChunk(collName, kKeyPattern.globalMin(), kKeyPattern.globalMax(), kShardId0, version);
 
     // Going to request that this chunk gets migrated.
-    const std::vector<MigrateInfo> migrationRequests{{chunk1.getNS(), kShardId1, chunk1}};
+    const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}};
 
     auto future = launchAsync([this, chunk1, migrationRequests] {
         Client::initThreadIfNotAlready("Test");
@@ -757,7 +746,7 @@ TEST_F(MigrationManagerTest, InterruptMigration) {
         shardTargeterMock(txn.get(), kShardId0)->setFindHostReturnValue(kShardHost0);
 
         ASSERT_NOT_OK(_migrationManager->executeManualMigration(
-            txn.get(), {chunk.getNS(), kShardId1, chunk}, 0, kDefaultSecondaryThrottle, false));
+            txn.get(), {kShardId1, chunk}, 0, kDefaultSecondaryThrottle, false));
     });
 
     // Wait till the move chunk request gets sent and pretend that it is stuck by never responding
@@ -779,11 +768,8 @@ TEST_F(MigrationManagerTest, InterruptMigration) {
     future.timed_get(kFutureTimeout);
 
     // Ensure that no new migrations can be scheduled
-    ASSERT_NOT_OK(_migrationManager->executeManualMigration(operationContext(),
-                                                            {chunk.getNS(), kShardId1, chunk},
-                                                            0,
-                                                            kDefaultSecondaryThrottle,
-                                                            false));
+    ASSERT_NOT_OK(_migrationManager->executeManualMigration(
+        operationContext(), {kShardId1, chunk}, 0, kDefaultSecondaryThrottle, false));
 
     // Ensure that the migration manager is no longer handling any migrations.
     _migrationManager->drainActiveMigrations();
@@ -846,7 +832,7 @@ TEST_F(MigrationManagerTest, RestartMigrationManager) {
         shardTargeterMock(txn.get(), kShardId0)->setFindHostReturnValue(kShardHost0);
 
         ASSERT_OK(_migrationManager->executeManualMigration(
-            txn.get(), {chunk1.getNS(), kShardId1, chunk1}, 0, kDefaultSecondaryThrottle, false));
+            txn.get(), {kShardId1, chunk1}, 0, kDefaultSecondaryThrottle, false));
     });
 
     // Expect only one moveChunk command to be called.
@@ -866,12 +852,13 @@ TEST_F(MigrationManagerTest, MigrationRecovery) {
     // Set up the database and collection as sharded in the metadata.
     std::string dbName = "foo";
     std::string collName = "foo.bar";
-    ChunkVersion version(2, 0, OID::gen());
+    ChunkVersion version(1, 0, OID::gen());
 
     setUpDatabase(dbName, kShardId0);
     setUpCollection(collName, version);
 
-    // Set up two chunks in the metadata.
+    // Set up two chunks in the metadata and set up two fake active migrations by writing documents
+    // to the config.migrations collection.
     ChunkType chunk1 =
         setUpChunk(collName, kKeyPattern.globalMin(), BSON(kPattern << 49), kShardId0, version);
     version.incMinor();
@@ -881,17 +868,8 @@ TEST_F(MigrationManagerTest, MigrationRecovery) {
     _migrationManager->interruptAndDisableMigrations();
     _migrationManager->drainActiveMigrations();
 
-    // Set up two fake active migrations by writing documents to the config.migrations collection.
-    setUpMigration(collName,
-                   chunk1.getMin(),
-                   chunk1.getMax(),
-                   kShardId1.toString(),
-                   chunk1.getShard().toString());
-    setUpMigration(collName,
-                   chunk2.getMin(),
-                   chunk2.getMax(),
-                   kShardId3.toString(),
-                   chunk2.getShard().toString());
+    setUpMigration(chunk1, kShardId1.toString());
+    setUpMigration(chunk2, kShardId3.toString());
 
     _migrationManager->startRecoveryAndAcquireDistLocks(operationContext());
 
@@ -925,7 +903,7 @@ TEST_F(MigrationManagerTest, FailMigrationRecovery) {
     // Set up the database and collection as sharded in the metadata.
     std::string dbName = "foo";
     std::string collName = "foo.bar";
-    ChunkVersion version(2, 0, OID::gen());
+    ChunkVersion version(1, 0, OID::gen());
 
     setUpDatabase(dbName, kShardId0);
     setUpCollection(collName, version);
@@ -940,12 +918,7 @@ TEST_F(MigrationManagerTest, FailMigrationRecovery) {
     _migrationManager->interruptAndDisableMigrations();
     _migrationManager->drainActiveMigrations();
 
-    // Set up a parsable fake active migration document in the config.migrations collection.
-    setUpMigration(collName,
-                   chunk1.getMin(),
-                   chunk1.getMax(),
-                   kShardId1.toString(),
-                   chunk1.getShard().toString());
+    setUpMigration(chunk1, kShardId1.toString());
 
     // Set up a fake active migration document that will fail MigrationType parsing -- missing
     // field.
diff --git a/src/mongo/db/s/balancer/scoped_migration_request.cpp b/src/mongo/db/s/balancer/scoped_migration_request.cpp
index ebc3e293814..fc4667c1f0c 100644
--- a/src/mongo/db/s/balancer/scoped_migration_request.cpp
+++ b/src/mongo/db/s/balancer/scoped_migration_request.cpp
@@ -95,7 +95,8 @@ StatusWith<ScopedMigrationRequest> ScopedMigrationRequest::writeMigration(
     OperationContext* txn, const MigrateInfo& migrateInfo) {
 
     // Try to write a unique migration document to config.migrations.
-    MigrationType migrationType(migrateInfo);
+    const MigrationType migrationType(migrateInfo);
+
     for (int retry = 0; retry < kDuplicateKeyErrorMaxRetries; ++retry) {
         Status result = grid.catalogClient(txn)->insertConfigDocument(
             txn, MigrationType::ConfigNS, migrationType.toBSON(), kMajorityWriteConcern);
diff --git a/src/mongo/db/s/balancer/scoped_migration_request_test.cpp b/src/mongo/db/s/balancer/scoped_migration_request_test.cpp
index 0b6474eaa46..7e870c0ae49 100644
--- a/src/mongo/db/s/balancer/scoped_migration_request_test.cpp
+++ b/src/mongo/db/s/balancer/scoped_migration_request_test.cpp
@@ -104,7 +104,7 @@ MigrateInfo makeMigrateInfo() {
     ChunkType chunkType = assertGet(ChunkType::fromBSON(chunkBuilder.obj()));
     ASSERT_OK(chunkType.validate());
 
-    return MigrateInfo(kNs, kToShard, chunkType);
+    return MigrateInfo(kToShard, chunkType);
 }
 
 TEST_F(ScopedMigrationRequestTest, CreateScopedMigrationRequest) {
diff --git a/src/mongo/db/s/balancer/type_migration.cpp b/src/mongo/db/s/balancer/type_migration.cpp
index 6dd2fe50c23..a9a3a9c6ffc 100644
--- a/src/mongo/db/s/balancer/type_migration.cpp
+++ b/src/mongo/db/s/balancer/type_migration.cpp
@@ -34,6 +34,11 @@
 #include "mongo/s/catalog/type_chunk.h"
 
 namespace mongo {
+namespace {
+
+const StringData kChunkVersion = "chunkVersion"_sd;
+
+}  // namespace
 
 const std::string MigrationType::ConfigNS = "config.migrations";
 
@@ -51,7 +56,8 @@ MigrationType::MigrationType(MigrateInfo info)
       _min(info.minKey),
       _max(info.maxKey),
       _fromShard(info.from),
-      _toShard(info.to) {}
+      _toShard(info.to),
+      _chunkVersion(info.version) {}
 
 StatusWith<MigrationType> MigrationType::fromBSON(const BSONObj& source) {
     MigrationType migrationType;
@@ -79,7 +85,7 @@ StatusWith<MigrationType> MigrationType::fromBSON(const BSONObj& source) {
         Status status = bsonExtractStringField(source, toShard.name(), &migrationToShard);
         if (!status.isOK())
             return status;
-        migrationType._toShard = migrationToShard;
+        migrationType._toShard = std::move(migrationToShard);
     }
 
     {
@@ -87,7 +93,15 @@ StatusWith<MigrationType> MigrationType::fromBSON(const BSONObj& source) {
         Status status = bsonExtractStringField(source, fromShard.name(), &migrationFromShard);
         if (!status.isOK())
             return status;
-        migrationType._fromShard = migrationFromShard;
+        migrationType._fromShard = std::move(migrationFromShard);
+    }
+
+    {
+        auto chunkVersionStatus =
+            ChunkVersion::parseFromBSONWithFieldForCommands(source, kChunkVersion);
+        if (!chunkVersionStatus.isOK())
+            return chunkVersionStatus.getStatus();
+        migrationType._chunkVersion = chunkVersionStatus.getValue();
     }
 
     return migrationType;
@@ -95,28 +109,34 @@ StatusWith<MigrationType> MigrationType::fromBSON(const BSONObj& source) {
 
 BSONObj MigrationType::toBSON() const {
     BSONObjBuilder builder;
-    if (_nss && _min)
-        builder.append(name.name(), getName());
-    if (_nss)
-        builder.append(ns.name(), _nss->ns());
-    if (_min)
-        builder.append(min.name(), _min.get());
-    if (_max)
-        builder.append(max.name(), _max.get());
-    if (_fromShard)
-        builder.append(fromShard.name(), _fromShard->toString());
-    if (_toShard)
-        builder.append(toShard.name(), _toShard->toString());
+
+    builder.append(name.name(), getName());
+    builder.append(ns.name(), _nss.ns());
+
+    builder.append(min.name(), _min);
+    builder.append(max.name(), _max);
+
+    builder.append(fromShard.name(), _fromShard.toString());
+    builder.append(toShard.name(), _toShard.toString());
+
+    _chunkVersion.appendWithFieldForCommands(&builder, kChunkVersion);
 
     return builder.obj();
 }
 
 MigrateInfo MigrationType::toMigrateInfo() const {
-    return MigrateInfo(_nss->ns(), _toShard.get(), _fromShard.get(), _min.get(), _max.get());
+    ChunkType chunk;
+    chunk.setNS(_nss.ns());
+    chunk.setShard(_fromShard);
+    chunk.setMin(_min);
+    chunk.setMax(_max);
+    chunk.setVersion(_chunkVersion);
+
+    return MigrateInfo(_toShard, chunk);
 }
 
 std::string MigrationType::getName() const {
-    return ChunkType::genID(_nss->ns(), _min.get());
+    return ChunkType::genID(_nss.ns(), _min);
 }
 
 }  // namespace mongo
diff --git a/src/mongo/db/s/balancer/type_migration.h b/src/mongo/db/s/balancer/type_migration.h
index 41d6ed72f48..bf741e30f3d 100644
--- a/src/mongo/db/s/balancer/type_migration.h
+++ b/src/mongo/db/s/balancer/type_migration.h
@@ -52,8 +52,6 @@ public:
     static const BSONField<BSONObj> max;
     static const BSONField<std::string> fromShard;
     static const BSONField<std::string> toShard;
-    static const BSONField<std::string> chunkVersionField;
-    static const BSONField<std::string> collectionVersionField;
 
     /**
      * The Balancer encapsulates migration information in MigrateInfo objects, so this facilitates
@@ -85,12 +83,13 @@ public:
 private:
     MigrationType();
 
-    // Required fields for config.migrations.
-    boost::optional<NamespaceString> _nss;
-    boost::optional<BSONObj> _min;
-    boost::optional<BSONObj> _max;
-    boost::optional<ShardId> _fromShard;
-    boost::optional<ShardId> _toShard;
+    // All required fields for config.migrations
+    NamespaceString _nss;
+    BSONObj _min;
+    BSONObj _max;
+    ShardId _fromShard;
+    ShardId _toShard;
+    ChunkVersion _chunkVersion;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/s/balancer/type_migration_test.cpp b/src/mongo/db/s/balancer/type_migration_test.cpp
index ffd0de4127b..eb04d585305 100644
--- a/src/mongo/db/s/balancer/type_migration_test.cpp
+++ b/src/mongo/db/s/balancer/type_migration_test.cpp
@@ -60,7 +60,7 @@ TEST(MigrationTypeTest, ConvertFromMigrationInfo) {
     ChunkType chunkType = assertGet(ChunkType::fromBSON(chunkBuilder.obj()));
     ASSERT_OK(chunkType.validate());
 
-    MigrateInfo migrateInfo(kNs, kToShard, chunkType);
+    MigrateInfo migrateInfo(kToShard, chunkType);
     MigrationType migrationType(migrateInfo);
 
     BSONObjBuilder builder;
@@ -70,6 +70,7 @@ TEST(MigrationTypeTest, ConvertFromMigrationInfo) {
     builder.append(MigrationType::max(), kMax);
     builder.append(MigrationType::fromShard(), kFromShard.toString());
     builder.append(MigrationType::toShard(), kToShard.toString());
+    version.appendWithFieldForCommands(&builder, "chunkVersion");
 
     BSONObj obj = builder.obj();
 
@@ -77,6 +78,8 @@ TEST(MigrationTypeTest, ConvertFromMigrationInfo) {
 }
 
 TEST(MigrationTypeTest, FromAndToBSON) {
+    const ChunkVersion version(1, 2, OID::gen());
+
     BSONObjBuilder builder;
     builder.append(MigrationType::name(), kName);
     builder.append(MigrationType::ns(), kNs);
@@ -84,6 +87,7 @@ TEST(MigrationTypeTest, FromAndToBSON) {
     builder.append(MigrationType::max(), kMax);
     builder.append(MigrationType::fromShard(), kFromShard.toString());
     builder.append(MigrationType::toShard(), kToShard.toString());
+    version.appendWithFieldForCommands(&builder, "chunkVersion");
 
     BSONObj obj = builder.obj();
 
@@ -92,11 +96,14 @@ TEST(MigrationTypeTest, FromAndToBSON) {
 }
 
 TEST(MigrationTypeTest, MissingRequiredNamespaceField) {
+    const ChunkVersion version(1, 2, OID::gen());
+
     BSONObjBuilder builder;
     builder.append(MigrationType::min(), kMin);
     builder.append(MigrationType::max(), kMax);
     builder.append(MigrationType::fromShard(), kFromShard.toString());
     builder.append(MigrationType::toShard(), kToShard.toString());
+    version.appendWithFieldForCommands(&builder, "chunkVersion");
 
     BSONObj obj = builder.obj();
 
@@ -106,11 +113,14 @@ TEST(MigrationTypeTest, MissingRequiredNamespaceField) {
 }
 
 TEST(MigrationTypeTest, MissingRequiredMinField) {
+    const ChunkVersion version(1, 2, OID::gen());
+
     BSONObjBuilder builder;
     builder.append(MigrationType::ns(), kNs);
     builder.append(MigrationType::max(), kMax);
     builder.append(MigrationType::fromShard(), kFromShard.toString());
     builder.append(MigrationType::toShard(), kToShard.toString());
+    version.appendWithFieldForCommands(&builder, "chunkVersion");
 
     BSONObj obj = builder.obj();
 
@@ -120,11 +130,14 @@ TEST(MigrationTypeTest, MissingRequiredMinField) {
 }
 
 TEST(MigrationTypeTest, MissingRequiredMaxField) {
+    const ChunkVersion version(1, 2, OID::gen());
+
     BSONObjBuilder builder;
     builder.append(MigrationType::ns(), kNs);
     builder.append(MigrationType::min(), kMin);
     builder.append(MigrationType::fromShard(), kFromShard.toString());
     builder.append(MigrationType::toShard(), kToShard.toString());
+    version.appendWithFieldForCommands(&builder, "chunkVersion");
 
     BSONObj obj = builder.obj();
 
@@ -134,11 +147,14 @@ TEST(MigrationTypeTest, MissingRequiredMaxField) {
 }
 
 TEST(MigrationTypeTest, MissingRequiredFromShardField) {
+    const ChunkVersion version(1, 2, OID::gen());
+
     BSONObjBuilder builder;
     builder.append(MigrationType::ns(), kNs);
     builder.append(MigrationType::min(), kMin);
     builder.append(MigrationType::max(), kMax);
     builder.append(MigrationType::toShard(), kToShard.toString());
+    version.appendWithFieldForCommands(&builder, "chunkVersion");
 
     BSONObj obj = builder.obj();
 
@@ -148,11 +164,14 @@ TEST(MigrationTypeTest, MissingRequiredFromShardField) {
 }
 
 TEST(MigrationTypeTest, MissingRequiredToShardField) {
+    const ChunkVersion version(1, 2, OID::gen());
+
     BSONObjBuilder builder;
     builder.append(MigrationType::ns(), kNs);
     builder.append(MigrationType::min(), kMin);
     builder.append(MigrationType::max(), kMax);
     builder.append(MigrationType::fromShard(), kFromShard.toString());
+    version.appendWithFieldForCommands(&builder, "chunkVersion");
 
     BSONObj obj = builder.obj();
 
@@ -161,5 +180,21 @@ TEST(MigrationTypeTest, MissingRequiredToShardField) {
     ASSERT_STRING_CONTAINS(migrationType.getStatus().reason(), MigrationType::toShard.name());
 }
 
+TEST(MigrationTypeTest, MissingRequiredVersionField) {
+    BSONObjBuilder builder;
+    builder.append(MigrationType::name(), kName);
+    builder.append(MigrationType::ns(), kNs);
+    builder.append(MigrationType::min(), kMin);
+    builder.append(MigrationType::max(), kMax);
+    builder.append(MigrationType::fromShard(), kFromShard.toString());
+    builder.append(MigrationType::toShard(), kToShard.toString());
+
+    BSONObj obj = builder.obj();
+
+    StatusWith<MigrationType> migrationType = MigrationType::fromBSON(obj);
+    ASSERT_EQUALS(migrationType.getStatus(), ErrorCodes::NoSuchKey);
+    ASSERT_STRING_CONTAINS(migrationType.getStatus().reason(), "chunkVersion");
+}
+
 }  // namespace
 }  // namespace mongo