MySQL Cluster 7.1.31 has been released

[Surya Narayana Murthy Narkedimilli]

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
      JavaScript/Node.js)
    - Active-Active/Multi-Master geographic replication

 MySQL Cluster 7.1.31, 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/7.1/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 7.1.31 (5.1.73-ndb-7.1.31) (2014-04-29)

    MySQL Cluster NDB 7.1.31 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 7.1
    releases.

    Obtaining MySQL Cluster NDB 7.1.  The latest MySQL Cluster NDB 7.1
    binaries for supported platforms can be obtained from
    http://dev.mysql.com/downloads/cluster/. Source code for the
    latest MySQL Cluster NDB 7.1 release can be obtained from the same
    location. You can also access the MySQL Cluster NDB 7.1
    development source tree at
 https://code.launchpad.net/~mysql/mysql-server/mysql-cluster-7.1.

    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 5.1 through
    MySQL 5.1.73 (see Changes in MySQL 5.1.73 (2013-12-03)
 (http://dev.mysql.com/doc/relnotes/mysql/5.1/en/news-5-1-73.html))
    .

    Functionality Added or Changed

      * Handling of LongMessageBuffer shortages and statistics has
        been improved as follows:

           + The default value of LongMessageBuffer has been increased
             from 4 MB to 64 MB.

          + When this resource is exhausted, a suitable informative
             message is now printed in the data node log describing
             possible causes of the problem and suggesting possible
             solutions.

           + LongMessageBuffer usage information is now shown in the
             ndbinfo.memoryusage table. See the description of this
             table for an example and additional information.

    Bugs Fixed

      * Important Change: The server system variables
        ndb_index_cache_entries and ndb_index_stat_freq, which had
        been deprecated in a previous MySQL Cluster release series,
        have now been removed. (Bug #11746486, Bug #26673)

      * When an ALTER TABLE statement changed table schemas without
        causing a change in the table's partitioning, the new table
        definition did not copy the hash map from the old definition,
        but used the current default hash map instead. However, the
        table data was not reorganized according to the new hashmap,
        which made some rows inaccessible using a primary key lookup
        if the two hash maps had incompatible definitions.
        To keep this situation from occurring, any ALTER TABLE that
        entails a hashmap change now triggers a reorganisation of the
        table. In addition, when copying a table definition in such
        cases, the hashmap is now also copied. (Bug #18436558)

      * When certain queries generated signals having more than 18
        data words prior to a node failure, such signals were not
        written correctly in the trace file. (Bug #18419554)

      * After dropping an NDB table, neither the cluster log nor the
        output of the REPORT MemoryUsage command showed that the
        IndexMemory used by that table had been freed, even though the
        memory had in fact been deallocated. This issue was introduced
        in MySQL Cluster NDB 7.1.28. (Bug #18296810)

      * ndb_show_tables sometimes failed with the error message Unable
        to connect to management server and immediately terminated,
        without providing the underlying reason for the failure. To
        provide more useful information in such cases, this program
        now also prints the most recent error from the
        Ndb_cluster_connection object used to instantiate the
        connection. (Bug #18276327)

      * The block threads managed by the multi-threading scheduler
        communicate by placing signals in an out queue or job buffer
        which is set up between all block threads. This queue has a
        fixed maximum size, such that when it is filled up, the worker
        thread must wait for the consumer to drain the queue. In a
        highly loaded system, multiple threads could end up in a
        circular wait lock due to full out buffers, such that they
        were preventing each other from performing any useful work.
        This condition eventually led to the data node being declared
        dead and killed by the watchdog timer.
        To fix this problem, we detect situations in which a circular
        wait lock is about to begin, and cause buffers which are
        otherwise held in reserve to become available for signal
        processing by queues which are highly loaded. (Bug #18229003)

      * The ndb_mgm client START BACKUP command (see Commands in the
        MySQL Cluster Management Client
 (http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-mgm-client-commands.html))
 could experience occasional random failures
        when a ping was received prior to an expected BackupCompleted
        event. Now the connection established by this command is not
        checked until it has been properly set up. (Bug #18165088)

      * Data nodes running ndbmtd could stall while performing an
        online upgrade of a MySQL Cluster containing a great many
        tables from a version prior to NDB 7.1.20 to version 7.1.20 or
        later. (Bug #16693068)

      * Cluster Replication: A slave in MySQL Cluster Replication now
        monitors the progression of epoch numbers received from its
        immediate upstream master, which can both serve as a useful
        check on the low-level functioning of replication, and provide
        a warning in the event replication is restarted accidentally
        at an already-applied position.
        As a result of this enhancement, an epoch ID collision has the
        following results, depending on the state of the slave SQL
        thread:

           + Following a RESET SLAVE statement, no action is taken, in
             order to allow the execution of this statement without
             spurious warnings.

          + Following START SLAVE, a warning is produced that the
             slave is being positioned at an epoch that has already
             been applied.

           + In all other cases, the slave SQL thread is stopped
             against the possibility that a system malfunction has
             resulted in the re-application of an existing epoch.
        (Bug #17461576)
        References: See also Bug #17369118.

      * Cluster API: When an NDB API client application received a
        signal with an invalid block or signal number, NDB provided
        only a very brief error message that did not accurately convey
        the nature of the problem. Now in such cases, appropriate
        printouts are provided when a bad signal or message is
        detected. In addition, the message length is now checked to
        make certain that it matches the size of the embedded signal.
        (Bug #18426180)

      * Cluster API: Refactoring that was performed in MySQL Cluster
        NDB 7.1.30 inadvertently introduced a dependency in Ndb.hpp on
        a file that is not included in the distribution, which caused
        NDB API applications to fail to compile. The dependency has
        been removed. (Bug #18293112, Bug #71803)
        References: This bug was introduced by Bug #17647637.

      * Cluster API: An NDB API application sends a scan query to a
        data node; the scan is processed by the transaction
        coordinator (TC). The TC forwards a LQHKEYREQ request to the
        appropriate LDM, and aborts the transaction if it does not
        receive a LQHKEYCONF response within the specified time limit.
        After the transaction is successfully aborted, the TC sends a
        TCROLLBACKREP to the NDBAPI client, and the NDB API client
        processes this message by cleaning up any Ndb objects
        associated with the transaction.
        The client receives the data which it has requested in the
        form of TRANSID_AI signals, buffered for sending at the data
        node, and may be delivered after a delay. On receiving such a
        signal, NDB checks the transaction state and ID: if these are
        as expected, it processes the signal using the Ndb objects
        associated with that transaction.
        The current bug occurs when all the following conditions are
        fulfilled:

           + The transaction coordinator aborts a transaction due to
             delays and sends a TCROLLBACPREP signal to the client,
             while at the same time a TRANSID_AI which has been
             buffered for delivery at an LDM is delivered to the same
             client.

           + The NDB API client considers the transaction complete on
             receipt of a TCROLLBACKREP signal, and immediately closes
             the transaction.

           + The client has a separate receiver thread running
             concurrently with the thread that is engaged in closing
             the transaction.

           + The arrival of the late TRANSID_AI interleaves with the
             closing of the user thread's transaction such that
             TRANSID_AI processing passes normal checks before
             closeTransaction() resets the transaction state and
             invalidates the receiver.
        When these conditions are all met, the receiver thread
        proceeds to continue working on the TRANSID_AI signal using
        the invalidated receiver. Since the receiver is already
        invalidated, its usage results in a node failure.
        Now the Ndb object cleanup done for TCROLLBACKREP includes
        invalidation of the transaction ID, so that, for a given
        transaction, any signal which is received after the
        TCROLLBACKREP arrives does not pass the transaction ID check
        and is silently dropped. This fix is also implemented for the
        TC_COMMITREF, TCROLLBACKREF, TCKEY_FAILCONF, and TCKEY_FAILREF
        signals as well.
        See also Operations and Signals
 (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-ndb-protocol-operations-signals.html)
 for additional information about
        NDB messaging. (Bug #18196562)

      * Cluster API: ndb_restore could sometimes report Error 701
        System busy with other schema operation unnecessarily when
        restoring in parallel. (Bug #17916243)

On behalf of the MySQL Cluster and the Oracle/MySQL RE Team,
Murthy Narkedimilli