Cassandra Kill back database Top 10, and Demand Java 7 version 2.0

After MySQL was acquired by Oracle, the industry has never stopped talking about the Open-source database, and the voice of PostgreSQL will be replaced as the most popular Open-source database. However, from the Db-engines rankings, the gap between PostgreSQL and MySQL is far more than "a few floors" so high (PostgreSQL not score a fraction of MySQL). Looking at the entire list of 193 databases, we will find that the NoSQL database has accounted for most of the traditional relational database management system only 75.

As the latest ranking of the September, the 2-3 battle between MySQL and Microsoft SQL Server has never stopped while Oracle sits on top of the list. However, regardless of the relational database, we will find that NoSQL's popularity has been greatly increased-in January 2013, MongoDB scored less than 100,cassandra scored only 30, while Cassandra is a few months after the absence of the first 10!

The

Cassandra, originally developed by Facebook and based on Amazon's proprietary, fully distributed database Dynamo, combines the type of column storage in Google BigTable, many of which can be called Dynamo 2.0, and then become the Apache top project. Cassandra, which soon became popular with many companies, including even heavyweight users such as Twitter, disappeared in the near future from Twtter, or even the mainstream product of Facebook, the original author.
Even once the altar has been pulled, Cassandra still has a large number of supporters, including the well-known data Open-source software company DataStax, and Cassandra can always be regulated hbase (noble descent, Natural integration with Hadoop) long hogging column storage first is a strong proof of its superiority.　　
Cassandra can return to top 10 and its 2.0 release is completely inseparable, DataStax CTO and co-founder Jonathan Ellis summed it up:
three major update
Lightweight transactions: Lightweight transactions ensure linear consistency of operations at the serialization isolation level provided by similar relational databases to prevent conflicts between concurrent requests.
CQL Elevation: CQL (Cassandra Query Language) enhances index support by enabling features such as cursors.
Support triggers: Triggers can drive performance-critical code closer to where it processes data, simplifying integration with event-driven frameworks such as Storm.
Other related updates
Performance tuning
Tracking statistics on cluster columns allows you to clear unnecessary sstable in the read path
Single-pass compaction roughly doubles the size of the large slice compression and reduces the JVM Heap and GC effects
When compression performance drops, hierarchical compression performs size-tiered compression on L0.　　Can inhibit the performance of the rise before the read performance deterioration, while the new version also significantly enhance the LCS sstable volume
for applications that still use thrift, Lmax disrupto based semi-asynchronous and semi-synchronous server will significantly reduce the cost of Thtift
　　Faster partition index queries and cache reads by increasing the performance of the heap outside memory
Jemalloc support for CRC32 allocations by switching from Adler to checksums for faster compressed data

Remove partition level ClothLong filter improves performance-eliminates the deserialization of the Teflon filter on each operation and reduces GC rollover.
Cleaning
Cancels the compatibility of the pre-1.2.5 sstable and pre-1.2.9 modes, has been updated to the latest version of 1.2.9
Cancel Supercolumns, and is replaced by a composite composition. The Supercolumn API is reserved, converted to transparent reverse compatibility (click to view details)
Potential risk countpendinghints JMX calls are replaced by hints created standards that are high-performance and can be monitored on a regular basis, It also eliminates the possibility that the Oom node may be
removed from the heap fragment cache, with only the remaining heap options
default Vnode, and the old token range code provided for the Vnode cluster disappears. When you do not use the Vnode node, manually specify a token or random selection. The
removes the standby memory load logic. This is to allow operators to have the proper hands-on space to cope with the heap load caused by the improper architecture, but it will never be as reliable as we think. The current important storage engine metadata is moved outside the heap, and memory shortages may explode prematurely.
Action-aware
Requirements Java7
Hierarchical compression of hierarchical information is saved to sstable metadata-each sstable is aware of the information, so a separate list is no longer needed. This makes the hierarchical compression more stable and the snapshot simpler.
Avoid loss of core page cache through optional row preheating
For more stability and transparency, the stream is overridden
streaming supports older versions of the sstable means that there is no need to manually run upgradesstables across the cluster before fixing, So you can load the snapshots in batches.