The following improvements to MySQL Cluster have been made in MySQL Cluster NDB 7.2:
Based on MySQL Server 5.5. Previous MySQL Cluster release series, including MySQL Cluster NDB 7.1, used MySQL 5.1 as a base. Beginning with MySQL Cluster NDB 7.2.1, MySQL Cluster NDB 7.2 is based on MySQL Server 5.5, so that MySQL Cluster users can benefit from MySQL 5.5's improvements in scalability and performance monitoring. As with MySQL 5.5, MySQL Cluster NDB 7.2.1 and later use CMake for configuring and building from source inh place of GNU autotools (used in MySQL 5.1 and MySQL Cluster releases based on MySQL 5.1). For more information about changes and improvements in MySQL 5.5, see Section 1.4, “What Is New in MySQL 5.5”.
Conflict detection using GCI Reflection.
MySQL Cluster Replication implements a new “primary
wins” conflict detection and resolution mechanism.
GCI Reflection applies in
two-cluster circulation “active-active”
replication setups, tracking the order in which changes
are applied on the MySQL Cluster designated as primary
relative to changes originating on the other MySQL Cluster
(referred to as the secondary). This relative ordering is
used to determine whether changes originating on the slave
are concurrent with any changes that originate locally,
and are therefore potentially in conflict. Two new
conflict detection functions are added: When using
NDB$EPOCH(), rows that are out of sync
on the secondary are realigned with those on the primary;
realignment is applied to transactions. For more
Section 17.6.11, “MySQL Cluster Replication Conflict Resolution”.
Version 2 binary log row events.
A new format for binary log row events, known as Version 2
binary log row events, provides support for improvements
in MySQL Cluster Replication conflict detection (see
previous item) and is intended to facilitate further
improvements in MySQL Replication. You can cause a given
mysqld use Version 1 or Version 2
binary logging row events with the
option. For backwards compatibility, Version 2 binary log
row events are also available in MySQL Cluster NDB 7.0
(7.0.27 and later) and MySQL Cluster NDB 7.1 (7.1.16 and
later). However, MySQL Cluster NDB 7.0 and MySQL Cluster
NDB 7.1 continue to use Version 1 binary log row events as
the default, whereas the default in MySQL Cluster NDB
7.2.1 and later is use Version 2 row events for binary
Distribution of MySQL users and privileges.
Automatic distribution of MySQL users and privileges
across all SQL nodes in a given MySQL Cluster is now
supported. To enable this support, you must first import
an SQL script
share/mysql/ndb_dist_priv.sql that is
included with the MySQL Cluster NDB 7.2 distribution. This
script creates several stored procedures which you can use
to enable privilege distribution and perform related
When a new MySQL Server joins a MySQL Cluster where privilege distribution is in effect, it also participates in the privilege distribution automatically.
Once privilege distribution is enabled, all changes to the
grant tables made on any mysqld attached
to the cluster are immediately available on any other
attached MySQL Servers. This is true whether the changes are
GRANT, or any of the other
statements described elsewhere in this Manual (see
Section 13.7.1, “Account Management Statements”.) This includes
privileges relating to stored routines and views; however,
automatic distribution of the views or stored routines
themselves is not currently supported.
For more information, see Section 17.5.14, “Distributed MySQL Privileges for MySQL Cluster”.
Distributed pushed-down joins.
Many joins can now be pushed down to the NDB kernel for
processing on MySQL Cluster data nodes. Previously, a join
was handled in MySQL Cluster by means of repeated accesses
NDB by the SQL node;
however, when pushed-down joins are enabled, a pushable
join is sent in its entirety to the data nodes, where it
can be distributed among the data nodes and executed in
parallel on multiple copies of the data, with a single,
merged result being returned to mysqld.
This can reduce greatly the number of round trips between
an SQL node and the data nodes required to handle such a
join, leading to greatly improved performance of join
It is possible to determine when joins can be pushed down to
the data nodes by examining the join with
EXPLAIN. A number of new
system status variables
additions to the
table (in the
information database) can also be helpful in determining
when and how well joins are being pushed down.
More information and examples are available in the
description of the
system variable. See also the description of the status
variables referenced in the previous paragraph, as well as
Section 184.108.40.206, “The
ndbinfo counters Table”.
Improved default values for data node configuration parameters.
In order to provide more resiliency to environmental
issues and better handling of some potential failure
scenarios, and to perform more reliably with increases in
memory and other resource requirements brought about by
recent improvements in join handling by
NDB, the default values for a
number of MySQL Cluster data node configuration parameters
have been changed. The parameters and changes are
described in the following list:
Default increased from 1500 ms to 5000 ms.
Default increased from 3000 ms to 7500 ms.
Now effectively disabled by default (default changed
from 4000 ms to 0).
Default increased from 20 MB to 128 MB.
Default increased from 32 to 256.
Beginning with MySQL Cluster NDB 7.2.10,
In addition, the value computed for
when this parameter is not set in
config.ini has been increased by a
factor of 4.
Fail-fast data nodes.
Beginning with MySQL Cluster NDB 7.2.1, data nodes handle
corrupted tuples in a fail-fast manner by default. This is
a change from previous versions of MySQL Cluster where
this behavior had to be enabled explicitly by enabling the
configuration parameter. In MySQL Cluster NDB 7.2.1 and
later, this parameter is enabled by default and must be
explicitly disabled, in which case data nodes merely log a
warning whenever they detect a corrupted tuple.
Memcache API support (ndbmemcache). The Memcached server is a distributed in-memory caching server that uses a simple text-based protocol. It is often employed with key-value stores. The Memcache API for MySQL Cluster, available beginning with MySQL Cluster NDB 7.2.2, is implemented as a loadable storage engine for memcached version 1.6 and later. This API can be used to access a persistent MySQL Cluster data store employing the memcache protocol. It is also possible for the memcached server to provide a strictly defined interface to existing MySQL Cluster tables.
Each memcache server can both cache data locally and access
data stored in MySQL Cluster directly. Caching policies are
configurable. For more information, see
ndbmemcache—Memcache API for MySQL Cluster, in the MySQL
Cluster API Developers Guide.
Rows per partition limit removed. Previously it was possible to store a maximum of 46137488 rows in a single MySQL Cluster partition—that is, per data node. Beginning with MySQL Cluster NDB 7.2.9, this limitation has been lifted, and there is no longer any practical upper limit to this number. (Bug #13844405, Bug #14000373)
MySQL Cluster NDB 7.2 is also supported by MySQL Cluster Manager, which provides an advanced command-line interface that can simplify many complex MySQL Cluster management tasks. See MySQL™ Cluster Manager 1.2.4 User Manual, for more information.
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