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MySQL Cluster 7.5.17 has been released
Posted by: Piotr Obrzut
Date: January 14, 2020 05:47AM

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, Memcached
    and JavaScript/Node.js)

MySQL Cluster 7.5.17 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.

MySQL Cluster 7.5 is also available from our repository for Linux
platforms, go here for details:

  https://dev.mysql.com/downloads/

The release notes are available from

http://dev.mysql.com/doc/relnotes/mysql-cluster/7.5/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 NDB Cluster 7.5.17 (5.7.29-ndb-7.5.17) (2020-01-14, General Availability)

   MySQL NDB Cluster 7.5.17 is a new release of MySQL NDB
   Cluster 7.5, based on MySQL Server 5.7 and including features
   in version 7.5 of the NDB
   (https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster.html)
   storage engine, as well as fixing recently discovered bugs in
   previous NDB Cluster releases.

   Obtaining MySQL NDB Cluster 7.5.  MySQL NDB Cluster 7.5
   source code and binaries can be obtained from
   https://dev.mysql.com/downloads/cluster/.

   For an overview of changes made in MySQL NDB Cluster 7.5, see
   What is New in NDB Cluster 7.5
(https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-what-is-new-7-5.html).

   This release also incorporates all bug fixes and changes made
   in previous NDB Cluster releases, as well as all bug fixes
   and feature changes which were added in mainline MySQL 5.7
   through MySQL 5.7.29 .

Bugs Fixed


     * Incompatible Change: The minimum value for the
       RedoOverCommitCounter
(https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redoovercommitcounter)
       data node configuration parameter has been increased from
       0 to 1. The minimum value for the RedoOverCommitLimit
(https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redoovercommitlimit)
       data node configuration parameter has also been increased
       from 0 to 1.
       You should check the cluster global configuration file
       and make any necessary adjustments to values set for
       these parameters before upgrading. (Bug #29752703)

     * Added the DUMP 9988
(https://dev.mysql.com/doc/ndb-internals/en/dump-command-9988.html)
       and DUMP 9989
(https://dev.mysql.com/doc/ndb-internals/en/dump-command-9989.html)
       commands. (Bug #30520103)

     * Execution of ndb_restore --rebuild-indexes
(https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-programs-ndb-restore.html#option_ndb_restore_rebuild-indexes)
       together with the --rewrite-database
(https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-programs-ndb-restore.html#option_ndb_restore_rewrite-database)
       and --exclude-missing-tables
(https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-programs-ndb-restore.html#option_ndb_restore_exclude-missing-tables)
       options did not create indexes for any tables
       in the target database. (Bug #30411122)

     * If a transaction was aborted while getting a page from
       the disk page buffer and the disk system was overloaded,
       the transaction hung indefinitely. This could also cause
       restarts to hang and node failure handling to fail. (Bug
       #30397083, Bug #30360681)
       References: See also: Bug #30152258.

     * Data node failures with the error Another node failed
       during system restart... occurred during a partial
       restart. (Bug #30368622)

     * The wrong number of bytes was reported in the cluster log
       for a completed local checkpoint. (Bug #30274618)
       References: See also: Bug #29942998.

     * The number of data bytes for the summary event written in
       the cluster log when a backup completed was truncated to
       32 bits, so that there was a significant mismatch between
       the number of log records and the number of data records
       printed in the log for this event. (Bug #29942998)

     * Using 2 LDM threads on a 2-node cluster with 10 threads
       per node could result in a partition imbalance, such that
       one of the LDM threads on each node was the primary for
       zero fragments. Trying to restore a multi-threaded backup
       from this cluster failed because the datafile for one LDM
       contained only the 12-byte data file header, which
       ndb_restore was unable to read. The same problem could
       occur in other cases, such as when taking a backup
       immediately after adding an empty node online.
       It was found that this occurred when ODirect
(https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndbd-definition.html#ndbparam-ndbd-odirect)
       was enabled for
       an EOF backup data file write whose size was less than
       512 bytes and the backup was in the STOPPING state. This
       normally occurs only for an aborted backup, but could
       also happen for a successful backup for which an LDM had
       no fragments. We fix the issue by introducing an
       additional check to ensure that writes are skipped only
       if the backup actually contains an error which should
       cause it to abort. (Bug #29892660)
       References: See also: Bug #30371389.

     * In some cases the SignalSender class, used as part of the
       implementation of ndb_mgmd and ndbinfo
(https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndbinfo.html),
       buffered excessive numbers of unneeded
       SUB_GCP_COMPLETE_REP and API_REGCONF signals, leading to
       unnecessary consumption of memory. (Bug #29520353)
       References: See also: Bug #20075747, Bug #29474136.

     * The maximum global checkpoint (GCP) commit lag and GCP
       save timeout are recalculated whenever a node shuts down,
       to take into account the change in number of data nodes.
       This could lead to the unintentional shutdown of a viable
       node when the threshold decreased below the previous
       value. (Bug #27664092)
       References: See also: Bug #26364729.

     * A transaction which inserts a child row may run
       concurrently with a transaction which deletes the parent
       row for that child. One of the transactions should be
       aborted in this case, lest an orphaned child row result.
       Before committing an insert on a child row, a read of the
       parent row is triggered to confirm that the parent
       exists. Similarly, before committing a delete on a parent
       row, a read or scan is performed to confirm that no child
       rows exist. When insert and delete transactions were run
       concurrently, their prepare and commit operations could
       interact in such a way that both transactions committed.
       This occurred because the triggered reads were performed
       using LM_CommittedRead locks (see NdbOperation::LockMode
(https://dev.mysql.com/doc/ndbapi/en/ndb-ndboperation-lockmode.html)),
       which are not strong enough to prevent such error scenarios.
       This problem is fixed by using the stronger LM_SimpleRead
       lock mode for both triggered reads. The use of
       LM_SimpleRead rather than LM_CommittedRead locks ensures
       that at least one transaction aborts in every possible
       scenario involving transactions which concurrently insert
       into child rows and delete from parent rows. (Bug
       #22180583)

     * Concurrent SELECT
       (https://dev.mysql.com/doc/refman/5.7/en/select.html) and
       ALTER TABLE
       (https://dev.mysql.com/doc/refman/5.7/en/alter-table.html
       ) statements on the same SQL node could sometimes block
       one another while waiting for locks to be released. (Bug
       #17812505, Bug #30383887)


On Behalf of MySQL Release Engineering Team

Piotr Obrzut 

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