0.5.0 beta
 * Allow multiple simultaneous flushes, improving flush throughput 
   on multicore systems (CASSANDRA-401)
 * Split up locks to improve write and read throughput on multicore systems
   (CASSANDRA-444, CASSANDRA-414)
 * More efficient use of memory during compaction (CASSANDRA-436)
 * autobootstrap option: when enabled, all non-seed nodes will attempt
   to bootstrap when started, until bootstrap successfully
   completes. -b option is removed.  (CASSANDRA-438)
 * Unless a token is manually specified in the configuration xml,
   a bootstraping node will use a token that gives it half the
   keys from the most-heavily-loaded node in the cluster,
   instead of generating a random token. 
   (CASSANDRA-385, CASSANDRA-517)
 * Miscellaneous bootstrap fixes (several tickets)
 * Ability to change a node's token even after it has data on it
   (CASSANDRA-541)
 * Ability to decommission a live node from the ring (CASSANDRA-435)
 * Semi-automatic loadbalancing via nodeprobe (CASSANDRA-192)
 * Add ability to set compaction thresholds at runtime via
   JMX / nodeprobe.  (CASSANDRA-465)
 * Add "comment" field to ColumnFamily definition. (CASSANDRA-481)
 * Additional JMX metrics (CASSANDRA-482)
 * JSON based export and import tools (several tickets)
 * Hinted Handoff fixes (several tickets)
 * Add key cache to improve read performance (CASSANDRA-423)
 * Simplified construction of custom ReplicationStrategy classes
   (CASSANDRA-497)
 * Add DCQUORUM, DCQUORUMSYNC consistency levels and corresponding
   ReplicationStrategy / EndpointSnitch classes.  Experimental.
   (CASSANDRA-492)
 * Web client interface added to contrib (CASSANDRA-457)
 * More-efficient flush for Random, CollatedOPP partitioners 
   for normal writes (CASSANDRA-446) and bulk load (CASSANDRA-420)
 * Add MemtableFlushAfterMinutes, a global replacement for the old 
   per-CF FlushPeriodInMinutes setting (CASSANDRA-463)
 * Datacenter quorum consistency levels (CASSANDRA-492)
 * optimizations to slice reading (CASSANDRA-350) and supercolumn
   queries (CASSANDRA-510)
 * force binding to given listenaddress for nodes with multiple
   interfaces (CASSANDRA-546)
 * stress.py benchmarking tool improvements (several tickets)
 * optimized replica placement code (CASSANDRA-525)
 * faster log replay on restart (CASSANDRA-539, CASSANDRA-540)
 * optimized local-node writes (CASSANDRA-558)
 * added get_range_slice, deprecating get_key_range (CASSANDRA-344)
 * expose TimedOutException to thrift (CASSANDRA-563)
 

0.4.2
 * Add validation disallowing null keys (CASSANDRA-486)
 * Fix race conditions in TCPConnectionManager (CASSANDRA-487)
 * Fix using non-utf8-aware comparison as a sanity check.
   (CASSANDRA-493)
 * Improve default garbage collector options (CASSANDRA-504)
 * Add "nodeprobe flush" (CASSANDRA-505)
 * remove NotFoundException from get_slice throws list (CASSANDRA-518)
 * fix get (not get_slice) of entire supercolumn (CASSANDRA-508)
 * fix null token during bootstrap (CASSANDRA-501)


0.4.1
 * Fix FlushPeriod columnfamily configuration regression
   (CASSANDRA-455)
 * Fix long column name support (CASSANDRA-460)
 * Fix for serializing a row that only contains tombstones
   (CASSANDRA-458)
 * Fix for discarding unneeded commitlog segments (CASSANDRA-459)
 * Add SnapshotBeforeCompaction configuration option (CASSANDRA-426)
 * Fix compaction abort under insufficient disk space (CASSANDRA-473)
 * Fix reading subcolumn slice from tombstoned CF (CASSANDRA-484)
 * Fix race condition in RVH causing occasional NPE (CASSANDRA-478)


0.4.0
 * fix get_key_range problems when a node is down (CASSANDRA-440)
   and add UnavailableException to more Thrift methods
 * Add example EndPointSnitch contrib code (several tickets)


0.4.0 RC2
 * fix SSTable generation clash during compaction (CASSANDRA-418)
 * reject method calls with null parameters (CASSANDRA-308)
 * properly order ranges in nodeprobe output (CASSANDRA-421)
 * fix logging of certain errors on executor threads (CASSANDRA-425)


0.4.0 RC1
 * Bootstrap feature is live; use -b on startup (several tickets)
 * Added multiget api (CASSANDRA-70)
 * fix Deadlock with SelectorManager.doProcess and TcpConnection.write
   (CASSANDRA-392)
 * remove key cache b/c of concurrency bugs in third-party
   CLHM library (CASSANDRA-405)
 * update non-major compaction logic to use two threshold values
   (CASSANDRA-407)
 * add periodic / batch commitlog sync modes (several tickets)
 * inline BatchMutation into batch_insert params (CASSANDRA-403)
 * allow setting the logging level at runtime via mbean (CASSANDRA-402)
 * change default comparator to BytesType (CASSANDRA-400)
 * add forwards-compatible ConsistencyLevel parameter to get_key_range
   (CASSANDRA-322)
 * r/m special case of blocking for local destination when writing with 
   ConsistencyLevel.ZERO (CASSANDRA-399)
 * Fixes to make BinaryMemtable [bulk load interface] useful (CASSANDRA-337);
   see contrib/bmt_example for an example of using it.
 * More JMX properties added (several tickets)
 * Thrift changes (several tickets)
    - Merged _super get methods with the normal ones; return values
      are now of ColumnOrSuperColumn.
    - Similarly, merged batch_insert_super into batch_insert.



0.4.0 beta
 * On-disk data format has changed to allow billions of keys/rows per
   node instead of only millions
 * Multi-keyspace support
 * Scan all sstables for all queries to avoid situations where
   different types of operation on the same ColumnFamily could
   disagree on what data was present
 * Snapshot support via JMX
 * Thrift API has changed a _lot_:
    - removed time-sorted CFs; instead, user-defined comparators
      may be defined on the column names, which are now byte arrays.
      Default comparators are provided for UTF8, Bytes, Ascii, Long (i64),
      and UUID types.
    - removed colon-delimited strings in thrift api in favor of explicit
      structs such as ColumnPath, ColumnParent, etc.  Also normalized
      thrift struct and argument naming.
    - Added columnFamily argument to get_key_range.
    - Change signature of get_slice to accept starting and ending
      columns as well as an offset.  (This allows use of indexes.)
      Added "ascending" flag to allow reasonably-efficient reverse
      scans as well.  Removed get_slice_by_range as redundant.
    - get_key_range operates on one CF at a time
    - changed `block` boolean on insert methods to ConsistencyLevel enum,
      with options of NONE, ONE, QUORUM, and ALL.
    - added similar consistency_level parameter to read methods
    - column-name-set slice with no names given now returns zero columns
      instead of all of them.  ("all" can run your server out of memory.
      use a range-based slice with a high max column count instead.)
 * Removed the web interface. Node information can now be obtained by 
   using the newly introduced nodeprobe utility.
 * More JMX stats
 * Remove magic values from internals (e.g. special key to indicate
   when to flush memtables)
 * Rename configuration "table" to "keyspace"
 * Moved to crash-only design; no more shutdown (just kill the process)
 * Lots of bug fixes

Full list of issues resolved in 0.4 is at https://issues.apache.org/jira/secure/IssueNavigator.jspa?reset=true&&pid=12310865&fixfor=12313862&resolution=1&sorter/field=issuekey&sorter/order=DESC


0.3.0 RC3
 * Fix potential deadlock under load in TCPConnection.
   (CASSANDRA-220)


0.3.0 RC2
 * Fix possible data loss when server is stopped after replaying
   log but before new inserts force memtable flush.
   (CASSANDRA-204)
 * Added BUGS file


0.3.0 RC1
 * Range queries on keys, including user-defined key collation
 * Remove support
 * Workarounds for a weird bug in JDK select/register that seems
   particularly common on VM environments. Cassandra should deploy
   fine on EC2 now
 * Much improved infrastructure: the beginnings of a decent test suite
   ("ant test" for unit tests; "nosetests" for system tests), code
   coverage reporting, etc.
 * Expanded node status reporting via JMX
 * Improved error reporting/logging on both server and client
 * Reduced memory footprint in default configuration
 * Combined blocking and non-blocking versions of insert APIs
 * Added FlushPeriodInMinutes configuration parameter to force
   flushing of infrequently-updated ColumnFamilies