SERVER-12472 Fail MoveChunk if an index is needed on TO shard and data exists

2 files changed, 50 insertions, 0 deletions

diff --git a/jstests/sharding/move_chunk_missing_idx.js b/jstests/sharding/move_chunk_missing_idx.js
new file mode 100644
index 00000000000..d963f08ae1e
--- /dev/null
+++ b/jstests/sharding/move_chunk_missing_idx.js
@@ -0,0 +1,36 @@
+/**
+ * Test that migration should fail if the destination shard does not
+ * have the index and is not empty.
+ */
+
+var st = new ShardingTest({ shards: 2 });
+
+var testDB = st.s.getDB('test');
+
+testDB.adminCommand({ enableSharding: 'test' });
+testDB.adminCommand({ shardCollection: 'test.user', key: { x: 1 }});
+
+testDB.user.ensureIndex({ a: 1, b: 1 });
+testDB.user.ensureIndex({ z: 'hashed' });
+
+testDB.adminCommand({ split: 'test.user', middle: { x: 0 }});
+testDB.adminCommand({ split: 'test.user', middle: { x: 10 }});
+
+assert.commandWorked(testDB.adminCommand({ moveChunk: 'test.user',
+                                           find: { x: 0 },
+                                           to: 'shard0000' }));
+
+st.d0.getDB('test').user.dropIndex({ a: 1, b: 1 });
+
+assert.commandWorked(testDB.adminCommand({ moveChunk: 'test.user',
+                                           find: { x: 10 },
+                                           to: 'shard0000' }));
+
+st.d0.getDB('test').user.dropIndex({ a: 1, b: 1 });
+testDB.user.insert({ x: 10 });
+
+assert.commandFailed(testDB.adminCommand({ moveChunk: 'test.user',
+                                           find: { x: -10 },
+                                           to: 'shard0000' }));
+
+st.stop();
diff --git a/src/mongo/s/d_migrate.cpp b/src/mongo/s/d_migrate.cpp
index 718bf31aed6..8c9570d3d21 100644
--- a/src/mongo/s/d_migrate.cpp
+++ b/src/mongo/s/d_migrate.cpp
@@ -1682,6 +1682,20 @@ namespace mongo {
                         return;
                     }
 
+                    BSONObj idxPattern(idx["key"].Obj());
+                    bool hasIndex = collection->getIndexCatalog()->
+                            findIndexByKeyPattern(idxPattern, true /* include unfinished */);
+
+                    if (collection->numRecords() > 0 && !hasIndex) {
+                        errmsg = str::stream() << "aborting migration, shard is missing "
+                                               << "indexes and collection is not empty. "
+                                               << "Non-trivial index creation should be "
+                                               << "scheduled manually";
+                        warning() << errmsg;
+                        state = FAIL;
+                        return;
+                    }
+
                     Status status = collection->getIndexCatalog()->createIndex( idx, false );
                     if ( !status.isOK() && status.code() != ErrorCodes::IndexAlreadyExists ) {
                         errmsg = str::stream() << "failed to create index before migrating data. "