RethinkDB 2.2.0 发布，此版本引入了 atomic changefeeds，包含从数据库到 changefeed 结果的现有值，可以原子转换到流更新。
Atomic changefeeds 使得动态构建实时应用更简单：用户可以使用单个代码路径来填充应用的初始数据，并且继续接收实时数据更新。这大大提升了系统的性能，改进了系统伸缩性，提升 RethinkDB 集群大小。
兼容性
RethinkDB 1.16 以上版本可以自动迁移，但是升级之前需要备份好数据。
如果是 RethinkDB 1.14.x 或者 1.15.x 升级，需要先迁移二级索引：
安装 RethinkDB 2.0.5.
更新 RethinkDB Python 驱动 (sudo pip install 'rethinkdb<2.1.0').
重建索引： rethinkdb index-rebuild.
RethinkDB 1.13 及以下版本，用户需要手动使用： rethinkdb dump 升级
API 不兼容改进
Changefeeds on .orderBy.limit as well as .get queries previously provided initial results by default. You now need to include the optional argumentincludeInitial: true to .changes to achieve the same behavior.
The deprecated protocol buffer driver protocol is no longer supported. The newer JSON protocol is now the only supported driver protocol. Older drivers using the deprecated protocol no longer work with RethinkDB 2.2.0. See the drivers list for up-to-date drivers.
If you're using Java, please note that at the time of writing, existing community drivers have not been updated to use the newer JSON protocol. However, anofficial Java driver is in active development and will be available soon.
Certain argument errors that used to throw ReqlDriverError exceptions now throwReqlCompileError exceptions. See #4669 for a full list of changes.
支持的版本
RethinkDB 2.2.0 提供 Ubuntu 15.10 (Wily Werewolf) 和 CentOS 7 官方包，不再提供 Ubuntu 10.04 (Lucid Lynx) 包。
新特性
Added full support for atomic changefeeds through the include_initial optarg (#3579)
Added a values command to obtain the values of an object as an array (#2945)
Added a conn.server command to identify the server for a given connection (#3934)
Extended r.uuid to accept a string and work as a hash function (#4636)
改进
Server
Improved the scalability of range queries on sharded tables (#4343)
Improved the performance of between queries on secondary indexes (#4862)
Reduced the memory overhead for large data sets (#1951)
Redesigned the internal representation of queries to improve efficiency (#4601)
Removed the deprecated protocol buffer driver protocol (#4601)
Improved the construction of secondary indexes to make them resumable and to reduce their impact on any production workload (#4959)
Improved the performance when using getAll with a secondary index in some edge cases (#4948)
Removed the limit of 1024 concurrent changefeeds on a single connection (#4732)
Implemented automatically growing coroutine stacks to avoid stack overflows (#4462)
Optimized the deserialization of network messages to avoid an extra copy (#3734)
Added a raft_leader field to a table's status to expose its current Raft leader (#4902)
Made the handling of invalid lines in the 'logs' system table more robust (#4929)
ReQL
indexStatus now exposes the secondary index function (#3231)
Added an optarg called changefeed_queue_size to specify how many changes the server should buffer on a changefeed before generating an error (#3607)
Extended branch to accept an arbitrary number of conditions and values (#3199)
Strings can now contain null characters (except in primary keys) (#3163)
Streams can now be coerced directly to an object (#2802)
Made coerceTo('BOOL') consistent with branch (#3133)
Changefeeds on filter and map queries involving geospatial terms are now allowed (#4063)
Extended or and and to accept zero arguments (#4132)
Web UI
The Data Explorer now allows executing only parts of a query be selecting them (#4814)
All drivers
Improved the consistency of ReQL error types by throwing ReqlCompileError rather than ReqlDriverError for certain errors (#4669)
JavaScript driver
Added an eachAsync method on cursors that behaves like each but also returns a promise (#4784)
Python driver
Implemented an API to override the default JSON encoder and decoder (#4825, #4818)
Bug 修复
Server
Fixed a segmentation fault that could happen when disconnecting a server while having open changefeeds (#4972)
Updated the description of the --server-name parameter in rethinkdb --help (#4739)
Fixed a crash with the message "Guarantee failed: [ts->tv_nsec >= 0 && ts->tv_nsec < (1000LL * (1000LL * 1000LL))] " (#4931)
Fixed a problem where backfill jobs didn't get removed from the 'jobs' table (#4923)
Fixed a memory corruption that could trigger a segmentation fault duringgetIntersecting queries (#4937)
Fixed an issue that could stop data files from RethinkDB 1.13 from migrating properly (#4991)
Fixed a "Guarantee failed: [pair.second] key for entry_t already exists" crash when rapidly reconnecting servers (#4968)
Fixed an "Uncaught exception of type interrupted_exc_t" crash (#4977)
Added a check to catch r.minval and r.maxval values when writing to the'_debug_scratch' system table (#4032)
ReQL
Fixed the error message that's generated when passing in a function with the wrong arity (#4189)
Fixed a regression that caused r.asc("test") to not fail as it should (#4951)
JavaScript driver
Object keys in toString are now properly quoted (#4997)
下载：https://github.com/rethinkdb/rethinkdb/archive/v2.2.0.zip
RethinkDB 设计用来存储 JSON 文档的分布式数据库，可通过简单操作实现多机分布式存储。支持表的联合和分组查询。
软件详情：http://rethinkdb.com/blog/2.2-release/
来自:开源中国社区
