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MySQL Cluster 7.6.13 has been released
Posted by: Kent Boortz
Date: January 14, 2020 04:51PM

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, Memcached
and JavaScript/Node.js)

MySQL Cluster 7.6.13 has been released and can be downloaded from

https://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 7.6 is also available from our repository for Linux
platforms, go here for details:

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

The release notes are available from

https://dev.mysql.com/doc/relnotes/mysql-cluster/7.6/en/

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

https://www.mysql.com/products/cluster/

Enjoy !


==============================================================================

Changes in MySQL NDB Cluster 7.6.13 (5.7.29-ndb-7.6.13) (2020-01-14,
General Availability)

   MySQL NDB Cluster 7.6.13 is a new release of NDB 7.6, based
   on MySQL Server 5.7 and including features in version 7.6 of
   the NDB storage engine, as well as fixing recently discovered
   bugs in previous NDB Cluster releases.

   Obtaining NDB Cluster 7.6.  NDB Cluster 7.6 source code and
   binaries can be obtained from

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

   For an overview of changes made in NDB Cluster 7.6, see What
   is New in NDB Cluster 7.6

     https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-what-is-new-7-6.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 .


Functionality Added or Changed

     * Important Change: It is now possible to divide a backup
       into slices and to restore these in parallel using two
       new options implemented for the ndb_restore utility,
       making it possible to employ multiple instances of
       ndb_restore to restore subsets of roughly the same size
       of the backup in parallel, which should help to reduce
       the length of time required to restore an NDB Cluster
       from backup.

       The --num-slices options determines the number of slices
       into which the backup should be divided; --slice-id
       provides the ID of the slice (0 to 1 less than the number
       of slices) to be restored by ndb_restore.
       Up to 1024 slices are supported.
       For more information, see the descriptions of the
       --num-slices and --slice-id options. (Bug #30383937)

Bugs Fixed

     * Incompatible Change: The minimum value for the
       RedoOverCommitCounter data node configuration parameter
       has been increased from 0 to 1. The minimum value for the
       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)

     * Microsoft Windows; NDB Disk Data: On Windows, restarting
       a data node other than the master when using Disk Data
       tables led to a failure in TSMAN.
       (Bug #97436, Bug #30484272)

     * A faulty ndbrequire() introduced when implementing
       partial local checkpoints assumed that m_participatingLQH
       must be clear when receiving START_LCP_REQ, which is not
       necessarily true when a failure happens for the master
       after sending START_LCP_REQ and before handling any
       START_LCP_CONF signals. (Bug #30523457)

     * A local checkpoint sometimes hung when the master node
       failed while sending an LCP_COMPLETE_REP signal and it
       was sent to some nodes, but not all of them.
       (Bug #30520818)

     * Added the DUMP 9988 and DUMP 9989 commands.
       (Bug #30520103)

     * Execution of ndb_restore --rebuild-indexes together with
       the --rewrite-database and --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.

     * When synchronizing extent pages it was possible for the
       current local checkpoint (LCP) to stall indefinitely if a
       CONTINUEB signal for handling the LCP was still
       outstanding when receiving the FSWRITECONF signal for the
       last page written in the extent synchronization page. The
       LCP could also be restarted if another page was written
       from the data pages. It was also possible that this issue
       caused PREP_LCP pages to be written at times when they
       should not have been. (Bug #30397083)

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

     * If a SYNC_EXTENT_PAGES_REQ signal was received by PGMAN
       while dropping a log file group as part of a partial
       local checkpoint, and thus dropping the page locked by
       this block for processing next, the LCP terminated due to
       trying to access the page after it had already been
       dropped. (Bug #30305315)

     * 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 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, 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 setting for the BackupLogBufferSize configuration
       parameter was not honored. (Bug #29415012)

     * 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), 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 and ALTER TABLE 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
Kent Boortz



Edited 1 time(s). Last edit at 01/14/2020 04:53PM by Kent Boortz.

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