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From:Hery Ramilison Date:November 6 2014 12:11am
Subject:MySQL Cluster 7.4.2 has been released
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Dear MySQL Users,

MySQL Cluster 7.4.2 (Milestone Release) is a public milestone
release for MySQL Cluster 7.4.

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 7.4.2 DMR can be downloaded from the "Development
Releases" tab at

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

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

More details can be found at

Enjoy !


Changes in MySQL Cluster NDB 7.4.2 (5.6.21-ndb-7.4.2 2014-11-05)

    MySQL Cluster NDB 7.4.2 is a new release of MySQL Cluster,
    based on MySQL Server 5.6 and including features under
    development for version 7.4 of the NDB storage engine, as
    well as fixing a number of 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

    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 5.6.21 (see Changes in MySQL 5.6.21

    Functionality Added or Changed

      * After adding new data nodes to the configuration file of
        a MySQL Cluster having many API nodes, but prior to
        starting any of the data node processes, API nodes tried
        to connect to these "missing" data nodes several times
        per second, placing extra loads on management nodes and
        the network. To reduce unnecessary traffic caused in this
        way, it is now possible to control the amount of time
        that an API node waits between attempts to connect to
        data nodes which fail to respond; this is implemented in
        two new API node configuration parameters
        StartConnectBackoffMaxTime and ConnectBackoffMaxTime.

        Time elapsed during node connection attempts is not taken
        into account when applying these parameters, both of
        which are given in milliseconds with approximately 100 ms
        resolution. As long as the API node is not connected to
        any data nodes as described previously, the value of the
        StartConnectBackoffMaxTime parameter is applied;
        otherwise, ConnectBackoffMaxTime is used.

        In a MySQL Cluster with many unstarted data nodes, the
        values of these parameters can be raised to circumvent
        connection attempts to data nodes which have not yet
        begun to function in the cluster, as well as moderate
        high traffic to management nodes.

        For more information about the behavior of these
        parameters, see Defining SQL and Other API Nodes in a
        MySQL Cluster

    Bugs Fixed

      * Online downgrades to MySQL Cluster NDB 7.3 failed when a
        MySQL Cluster NDB 7.4 master attempted to request a local
        checkpoint with 32 fragments from a data node already
        running NDB 7.3, which supports only 2 fragments for
        LCPs. Now in such cases, the NDB 7.4 master determines
        how many fragments the data node can handle before making
        the request. (Bug#19600834)

      * The server side of an NDB transporter disconnected an
        incoming client connection very quickly during the
        handshake phase if the node at the server end was not yet
        ready to receive connections from the other node. This
        led to problems when the client immediately attempted
        once again to connect to the server socket, only to be
        disconnected again, and so on in a repeating loop, until
        it suceeded. Since each client connection attempt left
        behind a socket in TIME_WAIT, the number of sockets in
        TIME_WAIT increased rapidly, leading in turn to problems
        with the node on the server side of the transporter.

        Further analysis of the problem and code showed that the
        root of the problem lay in the handshake portion of the
        transporter connection protocol. To keep the issue
        described previously from occurring, the node at the
        server end now sends back a WAIT message instead of
        disconnecting the socket when the node is not yet ready
        to accept a handshake. This means that the client end
        should no longer need to create a new socket for the next
        retry, but can instead begin immediately with a new
        handshake hello message. (Bug#17257842)

      * Corrupted messages to data nodes sometimes went
        undetected, causing a bad signal to be delivered to a
        block which aborted the data node. This failure in
        combination with disconnecting nodes could in turn cause
        the entire cluster to shut down.

        To keep this from happening, additional checks are now
        made when unpacking signals received over TCP, including
        checks for byte order, compression flag (which must not
        be used), and the length of the next message in the
        receive buffer (if there is one).

        Whenever two consecutive unpacked messages fail the
        checks just described, the current message is assumed to
        be corrupted. In this case, the transporter is marked as
        having bad data and no more unpacking of messages occurs
        until the transporter is reconnected. In addition, an
        entry is written to the cluster log containing the error
        as well as a hex dump of the corrupted message.
        (Bug#73843, Bug#19582925)

      * During restore operations, an attribute's maximum length
        was used when reading variable-length attributes from the
        receive buffer instead of the attribute's actual length.
        (Bug#73312, Bug#19236945)

      * Cluster Replication: The fix for Bug#18770469 in the
        MySQL Server made changes in the transactional behavior
        of the temporary conversion tables used when replicating
        between tables with different schemas. These changes as
        implemented are not compatible with NDB, and thus the fix
        for this bug has been reverted in MySQL Cluster.
        References: See also Bug#19704825.

MySQL Cluster 7.4.2 has been releasedHery Ramilison6 Nov