On mongos, createIndexes is broadcast to all shards, rather than only shards that own data for the collection.

So, createIndexes can implicitly create collections on shards that don't own data for the collection. When this happens, the collection is implicitly created without the right collection options (collation, compression, etc).

This is a beginning-of-time bug:

• r3.4.6: https://github.com/mongodb/mongo/blob/r3.4.6/src/mongo/s/commands/commands_public.cpp#L228-L229
• r3.2.15: https://github.com/mongodb/mongo/blob/r3.2.15/src/mongo/s/commands/commands_public.cpp#L209
• v3.0.11: https://github.com/mongodb/mongo/blob/v3.0.11/src/mongo/s/commands_public.cpp#L361-L363
• v2.6: https://github.com/mongodb/mongo/blob/v2.6/src/mongo/s/commands_public.cpp#L284
• v2.4: https://github.com/mongodb/mongo/blob/v2.4/src/mongo/s/commands_public.cpp#L184
• v2.2: https://github.com/mongodb/mongo/blob/v2.2/src/mongo/s/commands_public.cpp#L185
• v2.0: https://github.com/mongodb/mongo/blob/v2.0/s/commands_public.cpp#L163