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MySQL Cluster 7.2.23 has been released

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 7.2.23, 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 7.2.23 (5.5.47-ndb-7.2.23) (2016-01-19)

   MySQL Cluster NDB 7.2.23 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

   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 5.5.47 (see Changes in MySQL 5.5.47

   Bugs Fixed

     * In debug builds, a WAIT_EVENT while polling caused
       excessive logging to stdout. (Bug #22203672)

     * When executing a schema operation such as CREATE TABLE on
       a MySQL Cluster with multiple SQL nodes, it was possible
       for the SQL node on which the operation was performed to
       time out while waiting for an acknowledgement from the
       others. This could occur when different SQL nodes had
       different settings for --ndb-log-updated-only,
       --ndb-log-update-as-write, or other mysqld options
       effecting binary logging by NDB.
       This happened due to the fact that, in order to
       distribute schema changes between them, all SQL nodes
       subscribe to changes in the ndb_schema system table, and
       that all SQL nodes are made aware of each others
       subscriptions by subscribing to TE_SUBSCRIBE and
       TE_UNSUBSCRIBE events. The names of events to subscribe
       to are constructed from the table names, adding REPL$ or
       REPLF$ as a prefix. REPLF$ is used when full binary
       logging is specified for the table. The issue described
       previously arose because different values for the options
       mentioned could lead to different events being subscribed
       to by different SQL nodes, meaning that all SQL nodes
       were not necessarily aware of each other, so that the
       code that handled waiting for schema distribution to
       complete did not work as designed.
       To fix this issue, MySQL Cluster now treats the
       ndb_schema table as a special case and enforces full
       binary logging at all times for this table, independent
       of any settings for mysqld binary logging options. (Bug
       #22174287, Bug #79188)

     * Using ndb_mgm STOP -f to force a node shutdown even when
       it triggered a complete shutdown of the cluster, it was
       possible to lose data when a sufficient number of nodes
       were shut down, triggering a cluster shutodwn, and the
       timing was such that SUMA handovers had been made to
       nodes already in the process of shutting down. (Bug

     * The internal NdbEventBuffer::set_total_buckets() method
       calculated the number of remaining buckets incorrectly.
       This caused any incomplete epoch to be prematurely
       completed when the SUB_START_CONF signal arrived out of
       order. Any events belonging to this epoch arriving later
       were then ignored, and so effectively lost, which
       resulted in schema changes not being distributed
       correctly among SQL nodes. (Bug #79635, Bug #22363510)

     * Schema events were appended to the binary log out of
       order relative to non-schema events. This was caused by
       the fact that the binlog injector did not properly handle
       the case where schema events and non-schema events were
       from different epochs.
       This fix modifies the handling of events from the two
       schema and non-schema event streams such that events are
       now always handled one epoch at a time, starting with
       events from the oldest available epoch, without regard to
       the event stream in which they occur. (Bug #79077, Bug
       #22135584, Bug #20456664)

     * NDB failed during a node restart due to the status of the
       current local checkpoint being set but not as active,
       even though it could have other states under such
       conditions. (Bug #78780, Bug #21973758)

     * Cluster Replication: While the binary log injector thread
       was handling failure events, it was possible for all NDB
       tables to be left indefinitely in read-only mode. This
       was due to a race condition between the binlog injector
       thread and the utility thread handling events on the
       ndb_schema table, and to the fact that, when handling
       failure events, the binlog injector thread places all NDB
       tables in read-only mode until all such events are
       handled and the thread restarts itself.
       When the binlog inject thread receives a group of one or
       more failure events, it drops all other existing event
       operations and expects no more events from the utility
       thread until it has handled all of the failure events and
       then restarted itself. However, it was possible for the
       utility thread to continue attempting binary log setup
       while the injector thread was handling failures and thus
       attempting to create the schema distribution tables as
       well as event subscriptions on these tables. If the
       creation of these tables and event subscriptions occurred
       during this time, the binlog injector thread's
       expectation that there were no further event operations
       was never met; thus, the injector thread never restarted,
       and NDB tables remained in read-only as described
       To fix this problem, the Ndb object that handles schema
       events is now definitely dropped once the ndb_schema
       table drop event is handled, so that the utility thread
       cannot create any new events until after the injector
       thread has restarted, at which time, a new Ndb object for
       handling schema events is created. (Bug #17674771, Bug
       #19537961, Bug #22204186, Bug #22361695)

     * Cluster API: The binlog injector did not work correctly
       with TE_INCONSISTENT event type handling by
       Ndb::nextEvent(). (Bug #22135541)
       References: See also Bug #20646496.

     * Cluster API: Ndb::pollEvents() and pollEvents2() were
       slow to receive events, being dependent on other client
       threads or blocks to perform polling of transporters on
       their behalf. This fix allows a client thread to perform
       its own transporter polling when it has to wait in either
       of these methods.
       Introduction of transporter polling also revealed a
       problem with missing mutex protection in the
       ndbcluster_binlog handler, which has been added as part
       of this fix. (Bug #20957068, Bug #22224571, Bug #79311)

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