Hi!
Thank you for the patch set, good approach and overall it looks good to be 
merged. And there alos some points I would like to point.
Please consider what should happen if any other instance tries to connect to 
an anonymous replica. I think we could enable such replication if a connecting 
replica is anonymous to, however, this should be an object of a different issue 
so we could disable such behavior right now. At least we should handle 
replica_id = 0 while replication.
The last point I would like to mention is that a test with replication from an 
anonymous replica could be included.


On Sunday, 15 December 2019 23:56:14 MSK sergepetrenko wrote:
> Serge Petrenko (3):
>   box: update comment describing join protocol
>   replication: do not decode replicaset uuid when processing a subscribe
>   applier: split join processing into two stages
> 
> sergepetrenko (2):
>   vclock: ignore 0th component in comparisons.
>   replication: introduce anonymous replica.
> 
>  src/box/applier.cc              | 119 ++++++++++++--
>  src/box/applier.h               |   4 +
>  src/box/box.cc                  | 278 ++++++++++++++++++++++++++++++--
>  src/box/box.h                   |  11 +-
>  src/box/iproto.cc               |  16 +-
>  src/box/iproto_constants.h      |   6 +
>  src/box/lua/cfg.cc              |  14 +-
>  src/box/lua/info.c              |   4 +-
>  src/box/lua/load_cfg.lua        |   4 +
>  src/box/recovery.cc             |   7 +-
>  src/box/relay.cc                |  32 +++-
>  src/box/replication.cc          |  41 ++++-
>  src/box/replication.h           |  24 +++
>  src/box/vclock.h                |   7 +
>  src/box/wal.c                   |   4 +
>  src/box/xrow.c                  |  47 +++++-
>  src/box/xrow.h                  |  68 ++++++--
>  test/app-tap/init_script.result |  49 +++---
>  test/box/admin.result           |   2 +
>  test/box/cfg.result             |   4 +
>  test/replication/anon.lua       |  13 ++
>  test/replication/anon.result    | 259 +++++++++++++++++++++++++++++
>  test/replication/anon.test.lua  |  89 ++++++++++
>  test/replication/suite.cfg      |   1 +
>  test/unit/vclock.cc             |   8 +-
>  25 files changed, 1022 insertions(+), 89 deletions(-)
>  create mode 100644 test/replication/anon.lua
>  create mode 100644 test/replication/anon.result
>  create mode 100644 test/replication/anon.test.lua