MySQL Cluster 7.4.5 has been released

Dear MySQL Users,

MySQL Cluster is the distributed, shared-nothing variant of MySQL.
This storage engine provides:

   - In-Memory storage - Real-time performance (with optional
     checkpointing to disk)
   - Transparent Auto-Sharding - Read & write scalability
   - Active-Active/Multi-Master geographic replication
   - 99.999% High Availability with no single point of failure
     and on-line maintenance
   - NoSQL and SQL APIs (including C++, Java, http, Memcached
     and JavaScript/Node.js)

MySQL Cluster 7.4 makes significant advances in performance;
operational efficiency (such as enhanced reporting and faster restarts
and upgrades) and conflict detection and resolution for active-active
replication between MySQL Clusters.

MySQL Cluster 7.4.5 has been released and can be downloaded from

http://www.mysql.com/downloads/cluster/

where you will also find Quick Start guides to help you get your
first MySQL Cluster database up and running.

The release notes are available from

http://dev.mysql.com/doc/relnotes/mysql-cluster/7.4/en/index.html

MySQL Cluster enables users to meet the database challenges of next
generation web, cloud, and communications services with uncompromising
scalability, uptime and agility.

More details can be found at

http://www.mysql.com/products/cluster/

Enjoy !

Changes in MySQL Cluster NDB 7.4.5 (5.6.23-ndb-7.4.5) (2015-03-20)

    MySQL Cluster NDB 7.4.5 is a new release of MySQL Cluster 7.4, based
    on MySQL Server 5.6 and including new features in version 7.4 of the
    NDB storage engine, as well as fixing recently discovered bugs in
    previous MySQL Cluster releases.

    Obtaining MySQL Cluster NDB 7.4.  MySQL Cluster NDB 7.4 source code
    and binaries can be obtained from
http://dev.mysql.com/downloads/cluster/.

    For an overview of changes made in MySQL Cluster NDB 7.4, see MySQL
    Cluster Development in MySQL Cluster NDB 7.4
    (http://dev.mysql.com/doc/refman/5.6/en/mysql-cluster-develop
ment-5-6-ndb-7-4.html 
<http://dev.mysql.com/doc/refman/5.6/en/mysql-cluster-development-5-6-ndb-7-4.html>).

    This release also incorporates all bugfixes and changes made in
    previous MySQL Cluster releases, as well as all bugfixes and feature
    changes which were added in mainline MySQL 5.6 through MySQL 5.6.23
    (see Changes in MySQL 5.6.23 (2015-02-02)
    (http://dev.mysql.com/doc/relnotes/mysql/5.6/en/news-5-6-23.html)).

    Bugs Fixed

      * When reading and copying transporter short signal data,
        it was possible for the data to be copied back to the same signal
        with overlapping memory. (Bug #75930, Bug #20553247)

      * NDB node takeover code made the assumption that there
        would be only one takeover record when starting a takeover, based
        on the further assumption that the master node could never
        perform copying of fragments. However, this is not the case in a
        system restart, where a master node can have stale data and so
        need to perform such copying to bring itself up to date. (Bug
        #75919, Bug #20546899)

      * Cluster API: A scan operation, whether it is a single
        table scan or a query scan used by a pushed join, stores the
        result set in a buffer. This maximum size of this buffer is
        calculated and preallocated before the scan operation is started.
        This buffer may consume a considerable amount of memory; in some
        cases we observed a 2 GB buffer footprint in tests that executed
        100 parallel scans with 2 single-threaded (ndbd) data nodes.
        This memory consumption was found to scale linearly with
        additional fragments.  A number of root causes, listed here, were
        discovered that led to this problem:

           + Result rows were unpacked to full NdbRecord format before
           they were stored in the buffer. If only some but not all
           columns of a table were selected, the buffer contained empty
           space (essentially wasted).

           + Due to the buffer format being unpacked, VARCHAR and
           VARBINARY columns always had to be allocated for the maximum
           size defined for such columns.

           + BatchByteSize and MaxScanBatchSize values were not taken
           into consideration as a limiting factor when calculating the
           maximum buffer size.  These issues became more evident in NDB
           7.2 and later MySQL Cluster release series. This was due to
           the fact buffer size is scaled by BatchSize, and that the
           default value for this parameter was increased fourfold (from
           64 to 256) beginning with MySQL Cluster NDB 7.2.1.  This fix
           causes result rows to be buffered using the packed format
           instead of the unpacked format; a buffered scan result row is
           now not unpacked until it becomes the current row. In
           addition, BatchByteSize and MaxScanBatchSize are now used as
           limiting factors when calculating the required buffer size.
           Also as part of this fix, refactoring has been done to
           separate handling of buffered (packed) from handling of
           unbuffered result sets, and to remove code that had been
           unused since NDB 7.0 or earlier. The NdbRecord class
           declaration has also been cleaned up by removing a number of
           unused or redundant member variables. (Bug #73781, Bug #75599,
           Bug #19631350, Bug #20408733)

On behalf of Oracle/MySQL RE Team
Balasubramanian Kandasamy