Dear MySQL Users,

MySQL Cluster 7.4.8 (Milestone Release) is a public milestone
release for MySQL Cluster 7.4.

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 7.4 makes significant advances in performance;
operational efficiency (such as enhanced reporting and faster restarts
and upgrades) and conflict detection and resolution for active-active
replication between MySQL Clusters.

MySQL Cluster 7.4.8 DMR can be downloaded from the "Development
Releases" tab at

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/7.4/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.

As with any other pre-production release, caution should be taken when
installing on production level systems or systems with critical data.
More information on the Development Milestone Release process can be
found at


http://dev.mysql.com/doc/mysql-development-cycle/en/development-milestone-releases.html

More details can be found at

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

Enjoy !

Changes in MySQL Cluster NDB 7.4.8 (5.6.27-ndb-7.4.8 2015-10-16)

MySQL Cluster NDB 7.4.8 is a new release of MySQL Cluster
7.4, based on MySQL Server 5.6 and including features in
version 7.4 of the NDB storage engine, as well as fixing
recently discovered bugs in previous MySQL Cluster releases.

Obtaining MySQL Cluster NDB 7.4. MySQL Cluster NDB 7.4
source code and binaries can be obtained from
http://dev.mysql.com/downloads/cluster/.

For an overview of changes made in MySQL Cluster NDB 7.4, see
MySQL Cluster Development in MySQL Cluster NDB 7.4
(http://dev.mysql.com/doc/refman/5.6/en/mysql-cluster-develop
ment-5-6-ndb-7-4.html).

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 5.6
through MySQL 5.6.27 (see Changes in MySQL 5.6.27
(2015-09-30)
(http://dev.mysql.com/doc/relnotes/mysql/5.6/en/news-5-6-27.h
tml)).

Functionality Added or Changed

* Important Change; Cluster Replication: Added the
create_old_temporals server system variable to compliment
the system variables avoid_temporal_upgrade and
show_old_temporals introduced in MySQL 5.6.24 and
available in MySQL Cluster beginning with NDB 7.3.9 and
NDB 7.4.6. Enabling create_old_temporals causes mysqld to
use the storage format employed prior to MySQL 5.6.4 when
creating any DATE, DATETIME, or TIMESTAMP column---that
is, the column is created without any support for
fractional seconds. create_old_temporals is disabled by
default. The system variable is read-only; to enable the
use of pre-5.6.4 temporal types, set the equivalent
option (--create-old-temporals) on the command line, or
in an option file read by the MySQL server.
create_old_temporals is available only in MySQL Cluster;
it is not supported in the standard MySQL 5.6 server. It
is intended to facilitate upgrades from MySQL Cluster NDB
7.2 to MySQL Cluster NDB 7.3 and 7.4, after which table
columns of the affected types can be upgraded to the new
storage format. create_old_temporals is deprecated and
scheduled for removal in a future version of MySQL
Cluster.
avoid_temporal_upgrade must also be enabled for this
feature to work properly. You should also enable
show_old_temporals as well. For more information, see the
descriptions of these variables. For more about the
changes in MySQL's temporal types, see Storage
Requirements for Date and Time Types
(http://dev.mysql.com/doc/refman/5.6/en/storage-requireme
nts.html#data-types-storage-reqs-date-time). (Bug
#20701918)
References: See also Bug #21492598, Bug #72997, Bug
#18985760.

* When the --database option has not been specified for
ndb_show_tables, and no tables are found in the TEST_DB
database, an appropriate warning message is now issued.
(Bug #78379, Bug #11758430)

Bugs Fixed

* Important Change: When ndb_restore was run without
--disable-indexes or --rebuild-indexes on a table having
a unique index, it was possible for rows to be restored
in an order that resulted in duplicate values, causing it
to fail with duplicate key errors. Running ndb_restore on
such a table now requires using at least one of these
options; failing to do so now results in an error. (Bug
#57782, Bug #11764893)

* Important Change; Cluster API: The MGM API error-handling
functions ndb_mgm_get_latest_error(),
ndb_mgm_get_latest_error_msg(), and
ndb_mgm_get_latest_error_desc() each failed when used
with a NULL handle. You should note that, although these
functions are now null-safe, values returned in this case
are arbitrary and not meaningful. (Bug #78130, Bug
#21651706)

* mysql_upgrade failed when performing an upgrade from
MySQL Cluster NDB 7.2 to MySQL Cluster NDB 7.4. The root
cause of this issue was an accidental duplication of code
in mysql_fix_privilege_tables.sql that caused
ndbinfo_offline mode to be turned off too early, which in
turn led a subsequent CREATE VIEW statement to fail. (Bug
#21841821)

* ClusterMgr is a internal component of NDB API and
ndb_mgmd processes, part of TransporterFacade---which in
turn is a wrapper around the transporter registry---and
shared with data nodes. This component is responsible for
a number of tasks including connection setup requests;
sending and monitoring of heartbeats; provision of node
state information; handling of cluster disconnects and
reconnects; and forwarding of cluster state indicators.
ClusterMgr maintains a count of live nodes which is
incremented on receiving a report of a node having
connected (reportConnected() method call), and
decremented on receiving a report that a node has
disconnected (reportDisconnected()) from
TransporterRegistry. This count is checked within
reportDisconnected() to verify that is it greater than
zero.
The issue addressed here arose when node connections were
very brief due to send buffer exhaustion (among other
potential causes) and the check just described failed.
This occurred because, when a node did not fully connect,
it was still possible for the connection attempt to
trigger a reportDisconnected() call in spite of the fact
that the connection had not yet been reported to
ClusterMgr; thus, the pairing of reportConnected() and
reportDisconnected() calls was not guaranteed, which
could cause the count of connected nodes to be set to
zero even though there remained nodes that were still in
fact connected, causing node crashes with debug builds of
MySQL Cluster, and potential errors or other adverse
effects with release builds.
To fix this issue, ClusterMgr::reportDisconnected() now
verifies that a disconnected node had actually finished
connecting completely before checking and decrementing
the number of connected nodes. (Bug #21683144)
References: See also Bug #21664515, Bug #21651400.

* To reduce the possibility that a node's loopback
transporter becomes disconnected from the transporter
registry by reportError() due to send buffer exhaustion
(implemented by the fix for Bug #21651400), a portion of
the send buffer is now reserved for the use of this
transporter. (Bug #21664515)
References: See also Bug #21683144.

* The loopback transporter is similar to the TCP
transporter, but is used by a node to send signals to
itself as part of many internal operations. Like the TCP
transporter, it could be disconnected due to certain
conditions including send buffer exhaustion, but this
could result in blocking of TransporterFacade and so
cause multiple issues within an ndb_mgmd or API node
process. To prevent this, a node whose loopback
transporter becomes disconnected is now simply shut down,
rather than allowing the node process to hang. (Bug
#21651400)
References: See also Bug #21683144, Bug #21664515.

* The internal NdbEventBuffer object's active subscriptions
count (m_active_op_count) could be decremented more than
once when stopping a subscription when this action
failed, for example, due to a busy server and was
retried. Decrementing of this count could also fail when
communication with the data node failed, such as when a
timeout occurred. (Bug #21616263)
References: This bug is a regression of Bug #20575424,
Bug #20561446.

* In some cases, the management server daemon failed on
startup without reporting the reason. Now when ndb_mgmd
fails to start due to an error, the error message is
printed to stderr. (Bug #21571055)

* In a MySQL Cluster with multiple LDM instances, all
instances wrote to the node log, even inactive instances
on other nodes. During restarts, this caused the log to
be filled with messages from other nodes, such as the
messages shown here:
2015-06-24 00:20:16 [ndbd] INFO -- We are adjusting Max Disk
Write Speed,
a restart is ongoing now
...
2015-06-24 01:08:02 [ndbd] INFO -- We are adjusting Max Disk
Write Speed,
no restarts ongoing anymore

Now this logging is performed only by the active LDM
instance. (Bug #21362380)

* Backup block states were reported incorrectly during
backups. (Bug #21360188)
References: See also Bug #20204854, Bug #21372136.

* Added the BackupDiskWriteSpeedPct data node parameter.
Setting this parameter causes the data node to reserve a
percentage of its maximum write speed (as determined by
the value of MaxDiskWriteSpeed) for use in local
checkpoints while performing a backup.
BackupDiskWriteSpeedPct is interpreted as a percentage
which can be set between 0 and 90 inclusive, with a
default value of 50. (Bug #20204854)
References: See also Bug #21372136.

* When a data node is known to have been alive by other
nodes in the cluster at a given global checkpoint, but
its sysfile reports a lower GCI, the higher GCI is used
to determine which global checkpoint the data node can
recreate. This caused problems when the data node being
started had a clean file system (GCI = 0), or when it was
more than more global checkpoint behind the other nodes.
Now in such cases a higher GCI known by other nodes is
used only when it is at most one GCI ahead. (Bug
#19633824)
References: See also Bug #20334650, Bug #21899993. This
bug was introduced by Bug #29167.

* When restoring a specific database or databases with the
--include-databases or --exclude-databases option,
ndb_restore attempted to apply foreign keys on tables in
databases which were not among those being restored. (Bug
#18560951)

* After restoring the database schema from backup using
ndb_restore, auto-discovery of restored tables in
transactions having multiple statements did not work
correctly, resulting in Deadlock found when trying to get
lock; try restarting transaction errors.
This issue was encountered both in the mysql client, as
well as when such transactions were executed by
application programs using Connector/J and possibly other
MySQL APIs.
Prior to upgrading, this issue can be worked around by
executing SELECT TABLE_NAME, TABLE_SCHEMA FROM
INFORMATION_SCHEMA.TABLES WHERE ENGINE = 'NDBCLUSTER' on
all SQL nodes following the restore operation, before
executing any other statements. (Bug #18075170)

* ndb_desc used with the --extra-partition-info and
--blob-info options failed when run against a table
containing one or more TINYBLOB. columns. (Bug #14695968)

* Operations relating to global checkpoints in the internal
event data buffer could sometimes leak memory. (Bug
#78205, Bug #21689380)
References: See also Bug #76165, Bug #20651661.

* Trying to create an NDB table with a composite foreign
key referencing a composite primary key of the parent
table failed when one of the columns in the composite
foreign key was the table's primary key and in addition
this column also had a unique key. (Bug #78150, Bug
#21664899)

* When attempting to enable index statistics, creation of
the required system tables, events and event
subscriptions often fails when multiple mysqld processes
using index statistics are started concurrently in
conjunction with starting, restarting, or stopping the
cluster, or with node failure handling. This is normally
recoverable, since the affected mysqld process or
processes can (and do) retry these operations shortly
thereafter. For this reason, such failures are no longer
logged as warnings, but merely as informational events.
(Bug #77760, Bug #21462846)

* Adding a unique key to an NDB table failed when the table
already had a foreign key. Prior to upgrading, you can
work around this issue by creating the unique key first,
then adding the foreign key afterwards, using a separate
ALTER TABLE statement. (Bug #77457, Bug #20309828)

* Cluster Replication: When using conflict detection and
resolution with NDB$EPOCH2_TRANS()
(http://dev.mysql.com/doc/refman/5.6/en/mysql-cluster-rep
lication-conflict-resolution.html#mysql-cluster-replicati
on-ndb-epoch2-trans), delete-delete conflicts were not
handled in a transactional manner. (Bug #20713499)

* Cluster API: While executing dropEvent(), if the
coordinator DBDICT failed after the subscription manager
(SUMA block) had removed all subscriptions but before the
coordinator had deleted the event from the system table,
the dropped event remained in the table, causing any
subsequent drop or create event with the same name to
fail with NDB error 1419 Subscription already dropped or
error 746 Event name already exists. This occurred even
when calling dropEvent() with a nonzero force argument.
Now in such cases, error 1419 is ignored, and DBDICT
deletes the event from the table. (Bug #21554676)

* Cluster API: If the total amount of memory allocated for
the event buffer exceeded approximately 40 MB, the
calculation of memory usage percentages could overflow
during computation. This was due to the fact that the
associated routine used 32-bit arithmetic; this has now
been changed to use Uint64 values instead. (Bug #78454,
Bug #21847552)

* Cluster API: The nextEvent2() method continued to return
exceptional events such as TE_EMPTY, TE_INCONSISTENT, and
TE_OUT_OF_MEMORY for event operations which already had
been dropped. (Bug #78167, Bug #21673318)

* Cluster API: After the initial restart of a node
following a cluster failure, the cluster failure event
added as part of the restart process was deleted when an
event that existed prior to the restart was later
deleted. This meant that, in such cases, an Event API
client had no way of knowing that failure handling was
needed. In addition, the GCI used for the final cleanup
of deleted event operations, performed by pollEvents()
and nextEvent() when these methods have consumed all
available events, was lost. (Bug #78143, Bug #21660947)

* Cluster API: The internal value representing the latest
global checkpoint was not always updated when a completed
epoch of event buffers was inserted into the event queue.
This caused subsequent calls to Ndb::pollEvents() and
pollEvents2() to fail when trying to obtain the correct
GCI for the events available in the event buffers. This
could also result in later calls to nextEvent() or
nextEvent2() seeing events that had not yet been
discovered. (Bug #78129, Bug #21651536)

On Behalf of the MySQL/ORACLE RE Team
Hery Ramilison

--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql