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From:Hery Ramilison Date:September 26 2014 10:51am
Subject:MySQL Cluster 7.4.1 has been released
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Dear MySQL users,

MySQL Cluster 7.4.1 (Milestone Release) is the first public milestone
  release for  MySQL Cluster 7.4.

The MySQL Cluster 7.4.1 DMR can be downloaded from the Ā“Development
ReleasesĀ” tab at where you
will also find Quick Start guides to help you get your first MySQL
Cluster database up and running.

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

    - Real-time performance based on in-memory storage (with
      checkpointing to disk)
    - Read & write scalability through transparent auto-sharding
    - 99.999% High Availability with no single point of failure and
      on-line maintenance
    - SQL and NoSQL API (including C++, Java, http, Memcached and
    - Active-Active/Multi-Master geographic replication

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.

The release notes are available from:

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

As with any other pre-production release, caution should be taken when
installing on production level systems or systems with critical data.
More information on the Development Milestone Release process can be
found at

Note that 7.4.1 includes all features from MySQL Cluster 7.3.

More details can be found at


Changes in MySQL Cluster NDB 7.4.1 (5.6.20-ndb-7.4.1 2014-09-25)

MySQL Cluster NDB 7.4.1 is a new Developer Milestone release
of MySQL Cluster, based on MySQL Server 5.6 and previewing
new features under development for version 7.4 of the NDB
storage engine.

Obtaining MySQL Cluster NDB 7.4.  MySQL Cluster NDB 7.4
source code and binaries can be obtained from

For an overview of changes made in MySQL Cluster NDB 7.4, see
MySQL Cluster Development in MySQL Cluster NDB 7.4

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 5.6.20 (see Changes in MySQL 5.6.20 (2014-07-31)

Functionality Added or Changed

   * Performance: Several internal methods relating to the NDB
     receive thread have been optimized to make mysqld more
     efficient in processing SQL applications with the NDB
     storage engine. In particular, this work improves the
     performance of the NdbReceiver::execTRANSID_AI() method,
     which is commonly used to receive a record from the data
     nodes as part of a scan operation. (Since the receiver
     thread sometimes has to process millions of received
     records per second, it is critical that this method does
     not perform unnecessary work, or tie up resources that
     are not strictly needed.) The associated internal
     functions receive_ndb_packed_record() and
     handleReceivedSignal() methods have also been improved,
     and made more efficient.

   * Performance: A number of performance and other
     improvements have been made with regard to node starts
     and restarts. The following list contains a brief
     description of each of these changes:

        + Before memory allocated on startup can be used, it
          must be touched, causing the operating system to
          allocate the actual physical memory needed. The
          process of touching each page of memory that was
          allocated has now been multithreaded, with touch
          times on the order of 3 times shorter than with a
          single thread when performed by 16 threads.

        + When performing a node or system restart, it is
          necessary to restore local checkpoints for the
          fragments. This process previously used delayed
          signals at a point which was found to be critical to
          performance; these have now been replaced with
          normal (undelayed) signals, which should shorten
          significantly the time required to back up a MySQL
          Cluster or to restore it from backup.

        + Previously, there could be at most 2 LDM instances
          active with local checkpoints at any given time.
          Now, up to 16 LDMs can be used for performing this
          task, which increases utilization of available CPU
          power, and can speed up LCPs by a factor of 10,
          which in turn can greatly improve restart times.
          Better reporting of disk writes and increased
          control over these also make up a large part of this
          work. A new ndbinfo view
          disk_write_speed_aggreagate_node provides
          information about the speed of disk writes for each
          LDM thread that is in use. The
          DiskRestartCheckpointSpeed and
          DiskRestartCheckpointSpeedRestart configuration
          parameters have been deprecated, and are subject to
          removal in a future MySQL Cluster release. This
          release adds the data node configuration parameters
          MinDiskWriteSpeed, MaxDiskWriteSpeed,
          MaxDiskWriteSpeedOtherNodeRestart, and
          MaxDiskWriteSpeedOwnRestart to control write speeds
          for LCPs and backups when the present node, another
          node, or no node is currently restarting.
          For more information, see The ndbinfo
          disk_write_speed_aggregate_node Table
          , and the descriptions of the MySQL Cluster
          configuration parameters named previously.

        + Reporting of MySQL Cluster start phases has been
          improved, with more frequent printouts. New and
          better information about the start phases and their
          implementation has also been provided in the sources
          and documentation. See Summary of MySQL Cluster
          Start Phases

   * Information about memory usage by individual fragments
     can now be obtained from the memory_per_fragment view
     added in this release to the ndbinfo information
     database. This information includes pages having fixed,
     and variable element size, rows, fixed element free
     slots, variable element free bytes, and hash index memory
     usage. For information, see The ndbinfo
     memory_per_fragment Table

   * Cluster Replication: Using the ndb_slave_conflict_role
     server system variable introduced in this release, it is
     now possible to set the roles of primary and secondary
     explicitly and dynamically when using conflict detection
     and resolution with a circular or "active-active" MySQL
     Cluster Replication setup. This variable can take any one
     of the values PRIMARY, SECONDARY, PASS, or NULL (the
     default). (PASS enables a passthrough state in which the
     effects of any conflict resolution function are ignored.)
     This can be useful when it is necessary to fail over from
     the MySQL Cluster acting as the primary.
     The slave SQL thread must be stopped when the value of
     this variable is changed. In addition, it is not possible
     to change it directly between PASS and either of PRIMARY
     or SECONDARY.
     For more information, see the description of
     ndb_slave_conflict_role as well as MySQL Cluster
     Replication Conflict Resolution

   * Cluster Replication: A number of changes and improvements
     have been made to exceptions tables for MySQL Cluster
     Replication conflict detection and resolution. A reserved
     column name namespace is now employed for metacolumns,
     which allows the recording of an arbitrary subset of main
     table columns that are not part of the table's primary
     key. The names of all metacolumns in the exception table
     should now be prefixed with NDB$.
     It is no longer necessary to record the complete primary
     key. Matching of main table columns to exceptions table
     columns is now performed solely on the basis of name and
     type. In addition, you can now record in the exceptions
     table the values of columns which not part of the main
     table's primary key.
     Existing exceptions tables continue to be supported. For
     additional information, see MySQL Cluster Replication
     Conflict Resolution

On Behalf of the MySQL Cluster and the Oracle/MySQL RE Team
Hery Ramilison
MySQL Cluster 7.4.1 has been releasedHery Ramilison26 Sep