MySQL Cluster NDB 7.2.0 is a development preview release of
MySQL Cluster, incorporating several new features in the
NDB storage engine for testing and
Obtaining MySQL Cluster NDB 7.2. MySQL Cluster NDB 7.2.0 source code and binaries can be obtained from http://dev.mysql.com/downloads/cluster/.
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 5.1 through MySQL 5.1.51 (see Changes in MySQL 5.1.51 (2010-09-10)).
Functionality Added or Changed
Added support for pushing down joins to the NDB kernel for
parallel execution across the data nodes, which can speed up
execution of joins across
tables by a factor of 20 or more in some cases. Some
restrictions apply on the types of joins that can be optimized
in this way; in particular, columns to be joined must use
exactly the same data type, and cannot be any of the
TEXT types. In addition, columns
to be joined must be part of a table index or primary key.
Support for this feature can be enabled or disabled using the
ndb_join_pushdown server system
variable (enabled by default); see the description of this
variable for more information and examples.
As part of this improvement, the status variables
Ndb_pushed_reads also been
introduced for monitoring purposes. You can also see whether a
given join is pushed down using
EXPLAIN. In addition, several new
counters relating to push-down join performance have been added
counters table in the
ndbinfo database. For more
information, see the descriptions of the status variables
MySQL user privileges can now be distributed automatically
across all MySQL servers (SQL nodes) connected to the same MySQL
Cluster. Previously, each MySQL Server's user privilege
tables were required to use the
MyISAM storage engine, which meant
that a user account and its associated privileges created on one
SQL node were not available on any other SQL node without manual
intervention. MySQL Cluster now provides an SQL script file
ndb_dist_priv.sql that can be found in
share/mysql under the MySQL installation
directory; loading this script creates a stored procedure
mysql_cluster_move_privileges that can be
used following initial installation to convert the privilege
tables to the
NDB storage engine,
so that any time a MySQL user account is created, dropped, or
has its privileges updated on any SQL node, the changes take
effect immediately on all other MySQL servers attached to the
cluster. Note that you may need to execute
PRIVILEGES on any SQL nodes with connected MySQL
clients (or to disconnect and then reconnect the clients) in
order for those clients to be able to see the changes in
mysql_cluster_move_privileges has been
executed successfully, all MySQL user privileges are distributed
across all connected MySQL Servers. MySQL Servers that join the
cluster after this automatically participate in the privilege
ndb_dist_priv.sql also provides stored
routines that can be used to verify that the privilege tables
have been distributed successfully, and to perform other tasks.
For more information, see Distributed MySQL Privileges for MySQL Cluster.
The default values for a number of MySQL Cluster data node
configuration parameters have changed, 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 affected parameters are
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 20MB to 128MB.
Default increased from 32 to 256.
In addition, when
MaxNoOfLocalScans is not
specified, the value computed for it automatically has been
increased by a factor of 4 (that is, to 4 times
times the number of data nodes in the cluster).