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From:Balasubramanian Kandasamy Date:March 18 2016 10:28am
Subject:MySQL Cluster 7.5.1 has been released
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Dear MySQL Users,

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

   - In-Memory storage - Real-time performance
   - 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 7.5.1 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 7.5.1 (5.7.11-ndb-7.5.1) (2016-03-18,
Developer Milestone 2)

    MySQL Cluster NDB 7.5.1 is a new release of MySQL Cluster 7.5, based
    on MySQL Server 5.7 and including features in version 7.5 of the NDB
    ( storage
    engine, as well as fixing recently discovered bugs in previous MySQL
    Cluster releases.

    Obtaining MySQL Cluster NDB 7.5.  MySQL Cluster NDB 7.5 source code
    and binaries can be obtained from

    For an overview of changes made in MySQL Cluster NDB 7.5, see What is
    New in MySQL Cluster NDB 7.5

    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 5.7 through MySQL 5.7.11
    (see Changes in MySQL 5.7.11 (2016-02-05)

    Functionality Added or Changed

      * Scans have been improved by replacing the
        DIH_SCAN_GET_NODES_REQ signal, formerly used for communication
        between the DBTC and DBDIH kernel blocks in NDB
        with the DIGETNODESREQ signal, which supports direct execution
        and allows for the elimination of DIH_SCAN_GET_NODES_REF and
        DIH_SCAN_GET_NODES_CONF, as well as for DIH_SCAN_TAB_REQ and
        DIH_SCAN_TAB_COMPLETE_REP signals to EXECUTE_DIRECT. This enables
        enable higher scalability of data nodes when used for scan
        operations by decreasing the use of CPU resources for scan
        operations by an estimated five percent in some cases. This
        should also improve response times, which could help prevent
        issues with overload of the main threads.  As part of these
        changes, scans made in the BACKUP kernel block have also been
        improved and made more efficient.  References: See also Bug
        #80640, Bug #22884995.

      * The following improvements have been made to event buffer
        reporting in the cluster log:

           + Each report now identifies the API node that sent it.

           + The fields shown in the report have been improved and
           expanded. Percentages are now better specified and used only
           when appropriate. For improved clarity, the apply_epoch and
           latest_epoch fields have been renamed to latest_consumed_epoch
           and latest_buffered_epoch, respectively. The ID of the Ndb
           ( object
           serving as the source of the report is now shown, as is the
           reason for making the report (as the report_reason field).

           + The frequency of unnecessary reporting has been reduced by
           limiting reports to those showing only significant changes in
           event buffer usage.

           + The MGM API adds a new NDB_LE_EventBufferStatus2 event type
           to handle the additional information provided by the new event
           buffer reporting. The NDB_LE_EventBufferStatus event type used
           in older versions of MySQL Cluster is now deprecated, and will
           eventually be removed.  For more information, see Event Buffer
           Reporting in the Cluster Log

           as well as The ndb_logevent Structure

    Bugs Fixed

      * Important Change: The minimum value for the BackupDataBufferSize

        data node configuration parameter has been lowered from 2 MB to 
512 KB.
        The default and maximum values for this parameter remain unchanged.
        (Bug #22749509)

      * During node failure handling, the request structure used
        to drive the cleanup operation was not maintained correctly when
        the request was executed. This led to inconsistencies that were
        harmless during normal operation, but these could lead to
        assertion failures during node failure handling, with subsequent
        failure of additional nodes. (Bug #22643129)

      * The previous fix for a lack of mutex protection for the
        internal TransporterFacade::deliver_signal() function was found
        to be incomplete in some cases. (Bug #22615274) References: This
        bug was introduced by Bug #77225, Bug #21185585.

      * When setup of the binary log as an atomic operation one
        one SQL node failed, this could trigger a state in other SQL
        nodes in which they appeared to detect the SQL node participating
        in schema change distribution, whereas it had not yet completed
        binary log setup. This could in turn cause a deadlock on the
        global metadata lock when the SQL node still retrying binary log
        setup needed this lock, while another mysqld had taken the lock
        for itself as part of a schema change operation. In such cases,
        the second SQL node waited for the first one to act on its schema
        distribution changes, which it was not yet able to do. (Bug

      * Duplicate key errors could occur when ndb_restore was run
        on a backup containing a unique index. This was due to the fact
        that, during restoration of data, the database can pass through
        one or more inconsistent states prior to completion, such an
        inconsistent state possibly having duplicate values for a column
        which has a unique index.  (If the restoration of data is
        preceded by a run with --disable-indexes

        and followed by one with --rebuild-indexes

        these errors are avoided.) Added a check for unique indexes in the
        backup which is performed only when restoring data, and which
        does not process tables that have explicitly been excluded. For
        each unique index found, a warning is now printed. (Bug

      * When setting up event logging for ndb_mgmd on Windows,
        MySQL Cluster tries to add a registry key to HKEY_LOCAL_MACHINE,
        which fails if the user does not have access to the registry. In
        such cases ndb_mgmd logged the error Could neither create or open
        key, which is not accurate and which can cause confusion for
        users who may not realize that file logging is available and
        being used. Now in such cases, ndb_mgmd logs a warning Could not
        create or access the registry key needed for the application to
        log to the Windows EventLog. Run the application with sufficient
        privileges once to create the key, or add the key manually, or
        turn off logging for that application. An error (as opposed to a
        warning) is now reported in such cases only if there is no
        available output at all for ndb_mgmd event logging. (Bug

      * NdbDictionary
        metadata operations had a hard-coded 7-day timeout, which proved
        to be excessive for short-lived operations such as retrieval of
        table definitions. This could lead to unnecessary hangs in user
        applications which were difficult to detect and handle correctly.
        To help address this issue, timeout behaviour is modified so that
        read-only or short-duration dictionary interactions have a
        2-minute timeout, while schema transactions of potentially long
        duration retain the existing 7-day timeout.  Such timeouts are
        intended as a safety net: In the event of problems, these return
        control to users, who can then take corrective action. Any
        reproducible issue with NdbDictionary timeouts should be reported
        as a bug. (Bug #20368354)

      * Optimization of signal sending by buffering and sending
        them periodically, or when the buffer became full, could cause
        SUB_GCP_COMPLETE_ACK signals to be excessively delayed. Such
        signals are sent for each node and epoch, with a minimum interval
        of TimeBetweenEpochs

        if they are not received in time, the SUMA buffers can overflow
        as a result. The overflow caused API nodes to be disconnected, 
        to current transactions being aborted due to node failure. This
        condition made it difficult for long transactions (such as
        altering a very large table), to be completed. Now in such cases,
        the ACK signal is sent without being delayed. (Bug #18753341)

      * MySQL Cluster did not compile correctly with Microsoft
        Visual Studio 2015, due to a change from previous versions in the
        VS implementation of the _vsnprintf() function. (Bug #80276, Bug

      * When setting CPU spin time, the value was needlessly cast
        to a boolean internally, so that setting to it any nonzero value
        yielded an effective value of 1. This issue, as well as the fix
        for it, apply both to setting the SchedulerSpinTimer

        parameter and to setting spintime as part of a ThreadConfig

        parameter value. (Bug #80237, Bug #22647476)

      * Processing of local checkpoints was not handled correctly
        on Mac OS X, due to an uninitialized variable. (Bug #80236, Bug

      * A logic error in an if statement in
        storage/ndb/src/kernel/blocks/dbacc/DbaccMain.cpp rendered
        useless a check for determining whether ZREAD_ERROR should be
        returned when comparing operations.  This was detected when
        compiling with gcc using -Werror=logical-op. (Bug #80155, Bug
        #22601798) References: This bug was introduced by Bug #21285604.

      * Suppressed a CMake warning that was caused by use of an
        incorrectly quoted variable name. (Bug #80066, Bug #22572632)

      * When using CREATE INDEX
        ( to add
        an index on either of two NDB
        tables sharing circular foreign keys, the query succeeded but a
        temporary table was left on disk, breaking the foreign key
        constraints. This issue was also observed when attempting to
        create an index on a table in the middle of a chain of foreign
        keys---that is, a table having both parent and child keys, but on
        different tables. The problem did not occur when using ALTER
        TABLE (
        to perform the same index creation operation; and subsequent
        analysis revealed unintended differences in the way such
        operations were performed by CREATE INDEX.  To fix this problem,
        we now make sure that operations performed by a CREATE INDEX
        statement are always handled internally in the same way and at
        the same time that the same operations are handled when performed
        ( (Bug
        #79156, Bug #22173891)

      * The PortNumber SCI, SHM, and TCP configuration
        parameters, which were deprecated in MySQL 5.1.3, have now been
        removed and are no longer accepted in configuration files. This
        change does not affect the PortNumber

         management node configuration parameter, whose behavior remains
         unaltered. (Bug #77405, Bug #21280456)

      * Compilation of MySQL with Visual Studio 2015 failed in
        ConfigInfo.cpp, due to a change in Visual Studio's handling of
        spaces and concatenation.

      * For busy servers, client connection or communication
        failure could occur if an I/O-related system call was
        interrupted. The mysql_options()
        C API function now has a MYSQL_OPT_RETRY_COUNT option to control
        the number of retries for interrupted system calls. (Bug
        #22336527) References: See also Bug #22389653.

On behalf of the MySQL Release Team,
Balasubramanian Kandasamy

MySQL Cluster 7.5.1 has been releasedBalasubramanian Kandasamy18 Mar