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MySQL Cluster 7.2.17 has been released
Posted by: Sreedhar S
Date: July 11, 2014 12:02PM

 Dear MySQL users,

 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 7.2.17, has been released and can be downloaded from

 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.

 More details can be found at

 Enjoy !

 Changes in MySQL Cluster NDB 7.2.17 (5.5.38-ndb-7.2.17) (2014-11-07)

    MySQL Cluster NDB 7.2.17 is a new release of MySQL Cluster,
    incorporating new features in the NDBCLUSTER storage engine, and
    fixing recently discovered bugs in previous MySQL Cluster NDB 7.2
    development releases.

    Obtaining MySQL Cluster NDB 7.2.  MySQL Cluster NDB 7.2 source
    code and binaries can be obtained from

    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 5.5 through
    MySQL 5.5.38 (see Changes in MySQL 5.5.38 (2014-03-27)

    Functionality Added or Changed

      * Cluster API: Added as an aid to debugging the ability to
        specify a human-readable name for a given Ndb object and later
        to retrieve it. These operations are implemented,
        respectively, as the setNdbObjectName() and getNdbObjectName()
        To make tracing of event handling between a user application
        and NDB easier, you can use the reference (from getReference()
        followed by the name (if provided) in printouts; the reference
        ties together the application Ndb object, the event buffer,
        and the NDB storage engine's SUMA block. (Bug #18419907)

    Bugs Fixed

      * Processing a NODE_FAILREP signal that contained an invalid
        node ID could cause a data node to fail. (Bug #18993037, Bug
        References: This bug is a regression of Bug #16007980.

      * When building out of source, some files were written to the
        source directory instead of the build dir. These included the files used for creating ClusterJ jars and the
        pom.xml file used by In addition,
        ndbinfo.sql was written to the build directory, but marked as
        output to the source directory in CMakeLists.txt. (Bug
        #18889568, Bug #72843)

      * ndbmtd supports multiple parallel receiver threads, each of
        which performs signal reception for a subset of the remote
        node connections (transporters) with the mapping of
        remote_nodes to receiver threads decided at node startup.
        Connection control is managed by the multi-instance TRPMAN
        block, which is organized as a proxy and workers, and each
        receiver thread has a TRPMAN worker running locally.
        The QMGR block sends signals to TRPMAN to enable and disable
        communications with remote nodes. These signals are sent to
        the TRPMAN proxy, which forwards them to the workers. The
        workers themselves decide whether to act on signals, based on
        the set of remote nodes they manage.
        The current isuue arises because the mechanism used by the
        TRPMAN workers for determining which connections they are
        responsible for was implemented in such a way that each worker
        thought it was responsible for all connections. This resulted
        in the TRPMAN actions for OPEN_COMORD, ENABLE_COMREQ, and
        CLOSE_COMREQ being processed multiple times.
        The fix keeps TRPMAN instances (receiver threads) executing
        addition, the correct TRPMAN instance is now chosen when
        routing from this instance for a specific remote connection.
        (Bug #18518037)

      * Executing ALTER TABLE ... REORGANIZE PARTITION after
        increasing the number of data nodes in the cluster from 4 to
        16 led to a crash of the data nodes. This issue was shown to
        be a regression caused by previous fix which added a new dump
        handler using a dump code that was already in use (7019),
        which caused the command to execute two different handlers
        with different semantics. The new handler was assigned a new
        DUMP code (7024). (Bug #18550318)
        References: This bug is a regression of Bug #14220269.

      * When running with a very slow main thread, and one or more
        transaction coordinator threads, on different CPUs, it was
        possible to encounter a timeout when sending a
        DIH_SCAN_GET_NODESREQ signal, which could lead to a crash of
        the data node. Now in such cases the timeout is avoided. (Bug

      * During data node failure handling, the transaction coordinator
        performing takeover gathers all known state information for
        any failed TC instance transactions, determines whether each
        transaction has been committed or aborted, and informs any
        involved API nodes so that they can report this accurately to
        their clients. The TC instance provides this information by
        sending TCKEY_FAILREF or TCKEY_FAILCONF signals to the API
        nodes as appropriate top each affected transaction.
        In the event that this TC instance does not have a direct
        connection to the API node, it attempts to deliver the signal
        by routing it through another data node in the same node group
        as the failing TC, and sends a GSN_TCKEY_FAILREFCONF_R signal
        to TC block instance 0 in that data node. A problem arose in
        the case of multiple transaction cooridnators, when this TC
        instance did not have a signal handler for such signals, which
        led it to fail.
        This issue has been corrected by adding a handler to the TC
        proxy block which in such cases forwards the signal to one of
        the local TC worker instances, which in turn attempts to
        forward the signal on to the API node. (Bug #18455971)

      * A local checkpoint (LCP) is tracked using a global LCP state
        (c_lcpState), and each NDB table has a status indicator which
        indicates the LCP status of that table (tabLcpStatus). If the
        global LCP state is LCP_STATUS_IDLE, then all the tables
        should have an LCP status of TLS_COMPLETED.
        When an LCP starts, the global LCP status is LCP_INIT_TABLES
        and the thread starts setting all the NDB tables to
        TLS_ACTIVE. If any tables are not ready for LCP, the LCP
        initialization procedure continues with CONTINUEB signals
        until all tables have become available and been marked
        TLS_ACTIVE. When this initialization is complete, the global
        LCP status is set to LCP_STATUS_ACTIVE.
        This bug occurred when the following conditions were met:

           + An LCP was in the LCP_INIT_TABLES state, and some but not
             all tables had been set to TLS_ACTIVE.

           + The master node failed before the global LCP state
             changed to LCP_STATUS_ACTIVE; that is, before the LCP
             could finish processing all tables.

           + The NODE_FAILREP signal resulting from the node failure
             was processed before the final CONTINUEB signal from the
             LCP initialization process, so that the node failure was
             processed while the LCP remained in the LCP_INIT_TABLES

        Following master node failure and selection of a new one, the
        new master queries the remaining nodes with a MASTER_LCPREQ
        signal to determine the state of the LCP. At this point, since
        the LCP status was LCP_INIT_TABLES, the LCP status was reset
        to LCP_STATUS_IDLE. However, the LCP status of the tables was
        not modified, so there remained tables with TLS_ACTIVE.
        Afterwards, the failed node is removed from the LCP. If the
        LCP status of a given table is TLS_ACTIVE, there is a check
        that the global LCP status is not LCP_STATUS_IDLE; this check
        failed and caused the data node to fail.
        Now the MASTER_LCPREQ handler ensures that the tabLcpStatus
        for all tables is updated to TLS_COMPLETED when the global LCP
        status is changed to LCP_STATUS_IDLE. (Bug #18044717)

      * When performing a copying ALTER TABLE operation, mysqld
        creates a new copy of the table to be altered. This
        intermediate table, which is given a name bearing the prefix
        #sql-, has an updated schema but contains no data. mysqld then
        copies the data from the original table to this intermediate
        table, drops the original table, and finally renames the
        intermediate table with the name of the original table.
        mysqld regards such a table as a temporary table and does not
        include it in the output from SHOW TABLES; mysqldump also
        ignores an intermediate table. However, NDB sees no difference
        between such an intermediate table and any other table. This
        difference in how intermediate tables are viewed by mysqld
        (and MySQL client programs) and by the NDB storage engine can
        give rise to problems when performing a backup and restore if
        an intermediate table existed in NDB, possibly left over from
        a failed ALTER TABLE that used copying. If a schema backup is
        performed using mysqldump and the mysql client, this table is
        not included. However, in the case where a data backup was
        done using the ndb_mgm client's BACKUP command, the
        intermediate table was included, and was also included by
        ndb_restore, which then failed due to attempting to load data
        into a table which was not defined in the backed up schema.
        To prevent such failures from occurring, ndb_restore now by
        default ignores intermediate tables created during ALTER TABLE
        operations (that is, tables whose names begin with the prefix
        #sql-). A new option --exclude-intermediate-sql-tables is
        added that makes it possible to override the new behavior. The
        option's default value is TRUE; to cause ndb_restore to revert
        to the old behavior and to attempt to restore intermediate
        tables, set this option to FALSE. (Bug #17882305)

      * The logging of insert failures has been improved. This is
        intended to help diagnose occasional issues seen when writing
        to the mysql.ndb_binlog_index table. (Bug #17461625)

      * Employing a CHAR column that used the UTF8 character set as a
        table's primary key column led to node failure when restarting
        data nodes. Attempting to restore a table with such a primary
        key also caused ndb_restore to fail. (Bug #16895311, Bug

      * Cluster Replication: When using NDB$EPOCH_TRANS, conflicts
        between DELETE operations were handled like conflicts between
        updates, with the primary rejecting the transaction and
        dependents, and realigning the secondary. This meant that
        their behavior with regard to subsequent operations on any
        affected row or rows depended on whether they were in the same
        epoch or a different one: within the same epoch, they were
        considered conflicting events; in different epochs, they were
        not considered in conflict.
        This fix brings the handling of conflicts between deletes by
        NDB$EPOCH_TRANS with that performed when using NDB$EPOCH for
        conflict detection and resolution, and extends testing with
        NDB$EPOCH and NDB$EPOCH_TRANS to include "delete-delete"
        conflicts, and encapsulate the expected result, with
        transactional conflict handling modified so that a conflict
        between DELETE operations alone is not sufficient to cause a
        transaction to be considered in conflict. (Bug #18459944)

      * Cluster API: When an NDB data node indicates a buffer overflow
        via an empty epoch, the event buffer places an inconsistent
        data event in the event queue. When this was consumed, it was
        not removed from the event queue as expected, causing
        subsequent nextEvent() calls to return 0. This caused event
        consumption to stall because the inconsistency remained
        flagged forever, while event data accumulated in the queue.
        Event data belonging to an empty inconsistent epoch can be
        found either at the beginning or somewhere in the middle.
        pollEvents() returns 0 for the first case. This fix handles
        the second case: calling nextEvent() call dequeues the
        inconsistent event before it returns. In order to benefit from
        this fix, user applications must call nextEvent() even when
        pollEvents() returns 0. (Bug #18716991)

      * Cluster API: The pollEvents() method returned 1, even when
        called with a wait time equal to 0, and there were no events
        waiting in the queue. Now in such cases it returns 0 as
        expected. (Bug #18703871)

 On Behalf of the MySQL Cluster and the Oracle/MySQL RE Team


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MySQL Cluster 7.2.17 has been released
July 11, 2014 12:02PM

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