Change History
==============

1.0 (2012-03-28)
----------------

This version mainly comes with stabilized SQL tables format and efficient backup
feature, relying on replication, which has been fully reimplemented:

- It is now incremental, instead of being done on whole partitions.
  Schema of MySQL tables have been changed in order to optimize storage layout,
  for good partial replication performance.
- It runs at lowest priority not to degrade performance for client nodes.
- A cluster in the new BACKINGUP state is a client to a normal cluster and all
  its storage nodes are notified of invalidations and replicate from upstream
  nodes.

Other changes are:

- Compatibility with Python < 2.6 and ZODB < 3.9 has been dropped.
- Cluster is now automatically started when all storage nodes of UP_TO_DATE
  cells are available, similarly to ``mdadm assemble --no-degraded`` behaviour.
- NEO learned to check replicas, to detect data corruption or bugs during
  replication. When done on a backup cluster, upstream data is used as
  reference. This is still limited to data indexes (tid & oid/serial).
- NEO logs now are SQLite DB that always contain all debugging information
  including exchanged packets. Records are first kept in RAM, at most 16 MB by
  default, and there are flushed to disk only upon RTMIN signal or any important
  record. A 'neolog' script has been written to help reading such DB.
- Master addresses must be separated by spaces. '/' can't be used anymore.
- Adding and removing master nodes is now easier: unknown incoming master nodes
  are now accepted instead of rejected, and nodes can be given a path to a file
  that maintains a list of known master nodes.
- Node UUIDs have been shortened from 16 to 4 bytes, for better performance and
  easier debugging.

Also contains code clean-ups and bugfixes.

0.10.1 (2012-03-13)
-------------------

- Client didn't limit its memory usage when committing big transactions.
- Master failed to disconnect clients when cluster leaves RUNNING state.

0.10 (2011-10-17)
-----------------

- Storage was unable or slow to process large-sized transactions.
  This required to change protocol and MySQL tables format.
- NEO learned to store empty values (although it's useless when managed by
  a ZODB Connection).

0.9.2 (2011-10-17)
------------------

- storage: a specific socket can be given to MySQL backend
- storage: a ConflictError could happen when client is much faster than master
- 'verbose' command line option of 'neomigrate' did not work
- client: ZODB monkey-patch randomly raised a NameError

0.9.1 (2011-09-24)
------------------

- client: method to retrieve history of persistent objects was incompatible
  with recent ZODB and needlessly asked all storages systematically.
- neoctl: 'print node' command (to get list of all nodes) raised an
  AssertionError.
- 'neomigrate' raised a TypeError when converting NEO DB back to FileStorage.

0.9 (2011-09-12)
----------------

Initial release.

NEO is considered stable enough to replace existing ZEO setups, except that:

- there's no backup mechanism (aka efficient snapshoting): there's only
  replication and underlying MySQL tools

- MySQL tables format may change in the future
