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MySQL Cluster 7.2.19 has been released
Posted by: Kent Boortz
Date: January 25, 2015 07:51PM

Dear MySQL Users,

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 and Memcached)

MySQL Cluster 7.2.19, 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/7.2/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 7.2.19 (5.5.41-ndb-7.2.19) (2015-01-25)

   MySQL Cluster NDB 7.2.19 is a new release of MySQL Cluster,
   incorporating new features in the NDB 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
   http://dev.mysql.com/downloads/cluster/.

   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 5.5.41 (see Changes in MySQL 5.5.41 2014-11-28
   http://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-41.html).

   Bundled SSL Update (Commercial Releases)

     * Starting with this release, commercial distributions of
       MySQL Cluster NDB 7.2 are built using OpenSSL 1.0.1i.

   Bugs Fixed

     * The global checkpoint commit and save protocols can be
       delayed by various causes, including slow disk I/O. The
       DIH master node monitors the progress of both of these
       protocols, and can enforce a maximum lag time during
       which the protocols are stalled by killing the node
       responsible for the lag when it reaches this maximum.

       This DIH master GCP monitor mechanism did not perform its
       task more than once per master node; that is, it failed
       to continue monitoring after detecting and handling a GCP
       stop. (Bug #20128256)
       References: See also Bug #19858151.

     * A number of problems relating to the fired triggers pool
       have been fixed, including the following issues:

          + When the fired triggers pool was exhausted, NDB
            returned Error 218 (Out of LongMessageBuffer). A new
            error code 221 is added to cover this case.

          + An additional, separate case in which Error 218 was
            wrongly reported now returns the correct error.

          + Setting low values for MaxNoOfFiredTriggers led to
            an error when no memory was allocated if there was
            only one hash bucket.

          + An aborted transaction now releases any fired
            trigger records it held. Previously, these records
            were held until its ApiConnectRecord was reused by
            another transaction.

          + In addition, for the Fired Triggers pool in the
            internal ndbinfo.ndb$pools table, the high value
            always equalled the total, due to the fact that all
            records were momentarily seized when initializing
            them. Now the high value shows the maximum following
            completion of initialization.

       (Bug #19976428)

     * Online reorganization when using ndbmtd data nodes and
       with binary logging by mysqld enabled could sometimes
       lead to failures in the TRIX and DBLQH kernel blocks, or
       in silent data corruption. (Bug #19903481)
       References: See also Bug #19912988.

     * The local checkpoint ScanFrag watchdog and the global
       checkpoint monitor can each exclude a node when it is too
       slow when participating in their respective protocols.
       This exclusion was implemented by simply asking the
       failing node to shut down, which in case this was delayed
       (for whatever reason) could prolong the duration of the
       GCP or LCP stall for other, unaffected nodes.

       To minimize this time, an isolation mechanism has been
       added to both protocols whereby any other live nodes
       forcibly disconnect the failing node after a
       predetermined amount of time. This allows the failing
       node the opportunity to shut down gracefully (after
       logging debugging and other information) if possible, but
       limits the time that other nodes must wait for this to
       occur. Now, once the remaining live nodes have processed
       the disconnection of any failing nodes, they can commence
       failure handling and restart the related protocol or
       protocol, even if the failed node takes an excessively
       long time to shut down. (Bug #19858151)
       References: See also Bug #20128256.

     * A watchdog failure resulted from a hang while freeing a
       disk page in TUP_COMMITREQ, due to use of an
       uninitialized block variable. (Bug #19815044, Bug #74380)

     * Multiple threads crashing led to multiple sets of trace
       files being printed and possibly to deadlocks.
       (Bug #19724313)

     * When a client retried against a new master a schema
       transaction that failed previously against the previous
       master while the latter was restarting, the lock obtained
       by this transaction on the new master prevented the
       previous master from progressing past start phase 3 until
       the client was terminated, and resources held by it were
       cleaned up. (Bug #19712569, Bug #74154)

     * When a new data node started, API nodes were allowed to
       attempt to register themselves with the data node for
       executing transactions before the data node was ready.
       This forced the API node to wait an extra heartbeat
       interval before trying again.

       To address this issue, a number of HA_ERR_NO_CONNECTION
       errors (Error 4009) that could be issued during this time
       have been changed to Cluster temporarily unavailable
       errors (Error 4035), which should allow API nodes to use
       new data nodes more quickly than before. As part of this
       fix, some errors which were incorrectly categorized have
       been moved into the correct categories, and some errors
       which are no longer used have been removed.
       (Bug #19524096, Bug #73758)

     * When executing very large pushdown joins involving one or
       more indexes each defined over several columns, it was
       possible in some cases for the DBSPJ block
       (see The DBSPJ Block
       http://dev.mysql.com/doc/ndbapi/en/ndb-internals-kernel-blocks-dbspj.html)
       in the NDB kernel to generate SCAN_FRAGREQ signals that
       were excessively large. This caused data nodes to fail
       when these could not be handled correctly, due to a hard
       limit in the kernel on the size of such signals (32K).

       This fix bypasses that limitation by breaking up
       SCAN_FRAGREQ data that is too large for one such signal,
       and sending the SCAN_FRAGREQ as a chunked or fragmented
       signal instead. (Bug #19390895)

     * ndb_index_stat sometimes failed when used against a table
       containing unique indexes. (Bug #18715165)

     * Queries against tables containing a CHAR(0) columns
       failed with ERROR 1296 (HY000): Got error 4547
       'RecordSpecification has overlapping offsets' from
       NDBCLUSTER. (Bug #14798022)

     * ndb_restore failed while restoring a table which
       contained both a built-in conversion on the primary key
       and a staging conversion on a TEXT column.

       During staging, a BLOB table is created with a primary
       key column of the target type. However, a conversion
       function was not provided to convert the primary key
       values before loading them into the staging blob table,
       which resulted in corrupted primary key values in the
       staging BLOB table. While moving data from the staging
       table to the target table, the BLOB read failed because
       it could not find the primary key in the BLOB table.

       Now all BLOB tables are checked to see whether there are
       conversions on primary keys of their main tables. This
       check is done after all the main tables are processed, so
       that conversion functions and parameters have already
       been set for the main tables. Any conversion functions
       and parameters used for the primary key in the main table
       are now duplicated in the BLOB table.
       (Bug #73966, Bug #19642978)

     * 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)

     * Transporter send buffers were not updated properly
       following a failed send. (Bug #45043, Bug #20113145)

     * ndb_restore --print_data truncated TEXT and BLOB column
       values to 240 bytes rather than 256 bytes.

     * Disk Data: When a node acting as a DICT master fails, the
       arbitrator selects another node to take over in place of
       the failed node. During the takeover procedure, which
       includes cleaning up any schema transactions which are
       still open when the master failed, the disposition of the
       uncommitted schema transaction is decided. Normally this
       transaction be rolled back, but if it has completed a
       sufficient portion of a commit request, the new master
       finishes processing the commit. Until the fate of the
       transaction has been decided, no new TRANS_END_REQ
       messages from clients can be processed. In addition,
       since multiple concurrent schema transactions are not
       supported, takeover cleanup must be completed before any
       new transactions can be started.

       A similar restriction applies to any schema operations
       which are performed in the scope of an open schema
       transaction. The counter used to coordinate schema
       operation across all nodes is employed both during
       takeover processing and when executing any non-local
       schema operations. This means that starting a schema
       operation while its schema transaction is in the takeover
       phase causes this counter to be overwritten by concurrent
       uses, with unpredictable results.

       The scenarios just described were handled previously
       using a pseudo-random delay when recovering from a node
       failure. Now we check before the new master has rolled
       forward or backwards any schema transactions remaining
       after the failure of the previous master and avoid
       starting new schema transactions or performing operations
       using old transactions until takeover processing has
       cleaned up after the abandoned transaction.
       (Bug #19874809, Bug #74503)

     * Disk Data: When a node acting as DICT master fails, it is
       still possible to request that any open schema
       transaction be either committed or aborted by sending
       this request to the new DICT master. In this event, the
       new master takes over the schema transaction and reports
       back on whether the commit or abort request succeeded. In
       certain cases, it was possible for the new master to be
       misidentified---that is, the request was sent to the
       wrong node, which responded with an error that was
       interpreted by the client application as an aborted
       schema transaction, even in cases where the transaction
       could have been successfully committed, had the correct
       node been contacted. (Bug #74521, Bug #19880747)

     * Cluster Replication: It was possible using wildcards to
       set up conflict resolution for an exceptions table (that
       is, a table named using the suffix $EX), which should not
       be allowed. Now when a replication conflict function is
       defined using wildcard expressions, these are checked for
       possible matches so that, in the event that the function
       would cover an exceptions table, it is not set up for
       this table. (Bug #19267720)

     * Cluster API: The buffer allocated by an NdbScanOperation
       for receiving scanned rows was not released until the
       NdbTransaction owning the scan operation was closed. This
       could lead to excessive memory usage in an application
       where multiple scans were created within the same
       transaction, even if these scans were closed at the end
       of their lifecycle, unless NdbScanOperation::close() was
       invoked with the releaseOp argument equal to true. Now
       the buffer is released whenever the cursor navigating the
       result set is closed with NdbScanOperation::close(),
       regardless of the value of this argument.
       (Bug #75128, Bug #20166585)

     * ClusterJ: The following errors were logged at the SEVERE
       level; they are now logged at the NORMAL level, as they
       should be:

          + Duplicate primary key
          + Duplicate unique key
          + Foreign key constraint error: key does not exist
          + Foreign key constraint error: key exists

       (Bug #20045455)

     * ClusterJ: The com.mysql.clusterj.tie class gave off a
       logging message at the INFO logging level for every
       single query, which was unnecessary and was affecting the
       performance of applications that used ClusterJ.
       (Bug #20017292)

     * ClusterJ: ClusterJ reported a segmentation violation when
       an application closed a session factory while some
       sessions were still active. This was because MySQL
       Cluster allowed an Ndb_cluster_connection object be to
       deleted while some Ndb instances were still active, which
       might result in the usage of null pointers by ClusterJ.

       This fix stops that happening by preventing ClusterJ from
       closing a session factory when any of its sessions are
       still active. (Bug #19846392)
       References: See also Bug #19999242.

On behalf of the Oracle/MySQL RE Team,

Kent Boortz

Kent Boortz, Release Staff Engineer
Oracle, the MySQL team, www.mysql.com

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MySQL Cluster 7.2.19 has been released
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