What’s new in Cassandra 1.1

Cassandra 1.1 was just
released with some useful improvements over 1.0. We’ve been describing these as 1.1 was developed, but it’s useful to list them all in one place:

Cassandra 1.1 supports CQL3, with
support for compound keys and wide rows. Paul explains the
nuts and bolts of upgrading from CQL2 (which remains the default for now).
Caching has been completely updated to dramatically simplify tuning cache sizes. Just tell Cassandra how much total memory to use and it will allocate it
to your tables appropriately!
Support for mixing SSDs and magnetic storage, allocated by table.
Concurrent schema changes allow applications to create and destroy tables at will, with no schema locking required.
Row-level isolation means the Cassandra storage engine supports Atomicity, Isolation, and Durablity out of ACID. Readers always see either an old version of
a row, or the newest, never partially updated rows.
Live traffic sampling allows you to test drive performance tuning changes such as

compaction strategy or compression against live traffic without risking the stability of your production, client-facing nodes.
The BulkOutputFormat is a more-performant alternative to the old ColumnFamilyOutputFormat for Hadoop jobs.
Miscellaneous:

Hadoop can now handle Cassandra
wide rows by passing true to the new widerows parameter of
setInputColumnFamily. The WordCount example has been updated to cover this.
Compression is enabled by default (for newly created tables).
We now ship the stress load-testing tool in binary builds
SerializingCacheProvidor is now supported on Windows.