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ndb_config − extract NDB Cluster configuration information


ndb_config options


This tool extracts current configuration information for data nodes, SQL nodes, and API nodes from one of a number of sources: an NDB Cluster management node, or its config.ini or my.cnf file. By default, the management node is the source for the configuration data; to override the default, execute ndb_config with the −−config−file or −−mycnf option. It is also possible to use a data node as the source by specifying its node ID with −−config_from_node=node_id.

ndb_config can also provide an offline dump of all configuration parameters which can be used, along with their default, maximum, and minimum values and other information. The dump can be produced in either text or XML format; for more information, see the discussion of the −−configinfo and −−xml options later in this section).

You can filter the results by section (DB, SYSTEM, or CONNECTIONS) using one of the options −−nodes, −−system, or −−connections.

All options that can be used with ndb_config are shown in the following table. Additional descriptions follow the table.

Table 23.29. Command−line options used with the program ndb_config


Override defaults group suffix when reading cluster configuration sections in my.cnf; used in testing.

−−configinfo The −−configinfo option causes ndb_config to dump a list of each NDB Cluster configuration parameter supported by the NDB Cluster distribution of which ndb_config is a part, including the following information:

• A brief description of each parameter's purpose, effects, and usage

• The section of the config.ini file where the parameter may be used

• The parameter's data type or unit of measurement

• Where applicable, the parameter's default, minimum, and maximum values

• NDB Cluster release version and build information

By default, this output is in text format. Part of this output is shown here:

$> ndb_config −−configinfo
****** SYSTEM ******
Name (String)
Name of system (NDB Cluster)
PrimaryMGMNode (Non−negative Integer)
Node id of Primary ndb_mgmd(MGM) node
Default: 0 (Min: 0, Max: 4294967039)
ConfigGenerationNumber (Non−negative Integer)
Configuration generation number
Default: 0 (Min: 0, Max: 4294967039)
****** DB ******
MaxNoOfSubscriptions (Non−negative Integer)
Max no of subscriptions (default 0 == MaxNoOfTables)
Default: 0 (Min: 0, Max: 4294967039)
MaxNoOfSubscribers (Non−negative Integer)
Max no of subscribers (default 0 == 2 * MaxNoOfTables)
Default: 0 (Min: 0, Max: 4294967039)

Use this option together with the −−xml option to obtain output in XML format.


Gives the path to the management server's configuration file (config.ini). This may be a relative or absolute path. If the management node resides on a different host from the one on which ndb_config is invoked, then an absolute path must be used.


Obtain the cluster's configuration data from the data node that has this ID.

If the node having this ID is not a data node, ndb_config fails with an error. (To obtain configuration data from the management node instead, simply omit this option.)


Tells ndb_config to print CONNECTIONS information only—that is, information about parameters found in the [tcp], [tcp default], [shm], or [shm default] sections of the cluster configuration file (see Section, “NDB Cluster TCP/IP Connections”, and Section, “NDB Cluster Shared-Memory Connections”, for more information).

This option is mutually exclusive with −−nodes and −−system; only one of these 3 options can be used.


Print only configuration parameters that have non−default values.

−−fields=delimiter, −f delimiter

Specifies a delimiter string used to separate the fields in the result. The default is , (the comma character).

If the delimiter contains spaces or escapes (such as \n for the linefeed character), then it must be quoted.


Specifies the host name of the node for which configuration information is to be obtained.

While the hostname localhost usually resolves to the IP address, this may not necessarily be true for all operating platforms and configurations. This means that it is possible, when localhost is used in config.ini, for ndb_config −−host=localhost to fail if ndb_config is run on a different host where localhost resolves to a different address (for example, on some versions of SUSE Linux, this is In general, for best results, you should use numeric IP addresses for all NDB Cluster configuration values relating to hosts, or verify that all NDB Cluster hosts handle localhost in the same fashion.


Read configuration data from the my.cnf file.

−−ndb−connectstring=connection_string, −c connection_string

Specifies the connection string to use in connecting to the management server. The format for the connection string is the same as described in Section, “NDB Cluster Connection Strings”, and defaults to localhost:1186.


Do not read default options from any option file other than login file.


Specify the node ID of the node for which configuration information is to be obtained.


Tells ndb_config to print information relating only to parameters defined in an [ndbd] or [ndbd default] section of the cluster configuration file (see Section, “Defining NDB Cluster Data Nodes”).

This option is mutually exclusive with −−connections and −−system; only one of these 3 options can be used.

−−query=query−options, −q query−options

This is a comma−delimited list of query options—that is, a list of one or more node attributes to be returned. These include nodeid (node ID), type (node type—that is, ndbd, mysqld, or ndb_mgmd), and any configuration parameters whose values are to be obtained.

For example, −−query=nodeid,type,datamemory,datadir returns the node ID, node type, DataMemory, and DataDir for each node.

If a given parameter is not applicable to a certain type of node, than an empty string is returned for the corresponding value. See the examples later in this section for more information.

−−query−all, −a

Returns a comma−delimited list of all query options (node attributes; note that this list is a single string.

−−rows=separator, −r separator

Specifies a separator string used to separate the rows in the result. The default is a space character.

If the separator contains spaces or escapes (such as \n for the linefeed character), then it must be quoted.


Tells ndb_config to print SYSTEM information only. This consists of system variables that cannot be changed at run time; thus, there is no corresponding section of the cluster configuration file for them. They can be seen (prefixed with ****** SYSTEM ******) in the output of ndb_config −−configinfo.

This option is mutually exclusive with −−nodes and −−connections; only one of these 3 options can be used.


Filters results so that only configuration values applying to nodes of the specified node_type (ndbd, mysqld, or ndb_mgmd) are returned.

−−usage, −−help, or −?

Causes ndb_config to print a list of available options, and then exit.

−−version, −V

Causes ndb_config to print a version information string, and then exit.

−−configinfo −−xml

Cause ndb_config −−configinfo to provide output as XML by adding this option. A portion of such output is shown in this example:

$> ndb_config −−configinfo −−xml
<configvariables protocolversion="1" ndbversionstring="5.7.36−ndb−7.5.25"
ndbversion="460032" ndbversionmajor="7" ndbversionminor="5"
<section name="SYSTEM">
<param name="Name" comment="Name of system (NDB Cluster)" type="string"
<param name="PrimaryMGMNode" comment="Node id of Primary ndb_mgmd(MGM) node"
type="unsigned" default="0" min="0" max="4294967039"/>
<param name="ConfigGenerationNumber" comment="Configuration generation number"
type="unsigned" default="0" min="0" max="4294967039"/>
<section name="MYSQLD" primarykeys="NodeId">
<param name="wan" comment="Use WAN TCP setting as default" type="bool"
<param name="HostName" comment="Name of computer for this node"
type="string" default=""/>
<param name="Id" comment="NodeId" type="unsigned" mandatory="true"
min="1" max="255" deprecated="true"/>
<param name="NodeId" comment="Number identifying application node (mysqld(API))"
type="unsigned" mandatory="true" min="1" max="255"/>
<param name="ExecuteOnComputer" comment="HostName" type="string"

Normally, the XML output produced by ndb_config −−configinfo −−xml is formatted using one line per element; we have added extra whitespace in the previous example, as well as the next one, for reasons of legibility. This should not make any difference to applications using this output, since most XML processors either ignore nonessential whitespace as a matter of course, or can be instructed to do so.

The XML output also indicates when changing a given parameter requires that data nodes be restarted using the −−initial option. This is shown by the presence of an initial="true" attribute in the corresponding <param> element. In addition, the restart type (system or node) is also shown; if a given parameter requires a system restart, this is indicated by the presence of a restart="system" attribute in the corresponding <param> element. For example, changing the value set for the Diskless parameter requires a system initial restart, as shown here (with the restart and initial attributes highlighted for visibility):

<param name="Diskless" comment="Run wo/ disk" type="bool" default="false"
restart="system" initial="true"

Currently, no initial attribute is included in the XML output for <param> elements corresponding to parameters which do not require initial restarts; in other words, initial="false" is the default, and the value false should be assumed if the attribute is not present. Similarly, the default restart type is node (that is, an online or “rolling” restart of the cluster), but the restart attribute is included only if the restart type is system (meaning that all cluster nodes must be shut down at the same time, then restarted).

Deprecated parameters are indicated in the XML output by the deprecated attribute, as shown here:

<param name="NoOfDiskPagesToDiskAfterRestartACC" comment="DiskCheckpointSpeed"
type="unsigned" default="20" min="1" max="4294967039" deprecated="true"/>

In such cases, the comment refers to one or more parameters that supersede the deprecated parameter. Similarly to initial, the deprecated attribute is indicated only when the parameter is deprecated, with deprecated="true", and does not appear at all for parameters which are not deprecated. (Bug #21127135)

Parameters that are required are indicated with mandatory="true", as shown here:

<param name="NodeId"
comment="Number identifying application node (mysqld(API))"
type="unsigned" mandatory="true" min="1" max="255"/>

In much the same way that the initial or deprecated attribute is displayed only for a parameter that requires an intial restart or that is deprecated, the mandatory attribute is included only if the given parameter is actually required.

The −−xml option can be used only with the −−configinfo option. Using −−xml without −−configinfo fails with an error.

Unlike the options used with this program to obtain current configuration data, −−configinfo and −−xml use information obtained from the NDB Cluster sources when ndb_config was compiled. For this reason, no connection to a running NDB Cluster or access to a config.ini or my.cnf file is required for these two options.


Print program argument list and exit.


Read default options from given file only.


Read given file after global files are read.


Also read groups with concat(group, suffix).


Read given path from login file.


Display help text and exit.


Same as −−ndb−connectstring.


Same as −−ndb−connectstring.


Set node ID for this node, overriding any ID set by −−ndb−connectstring.


Write core file on error; used in debugging.


Directory containing character sets.


Number of times to retry connection before giving up.


Number of seconds to wait between attempts to contact management server.


Enable optimizations for selection of nodes for transactions. Enabled by default; use −−skip−ndb−optimized−node−selection to disable.

Combining other ndb_config options (such as −−query or −−type) with −−configinfo (with or without the −−xml option is not supported. Currently, if you attempt to do so, the usual result is that all other options besides −−configinfo or −−xml are simply ignored. However, this behavior is not guaranteed and is subject to change at any time. In addition, since ndb_config, when used with the −−configinfo option, does not access the NDB Cluster or read any files, trying to specify additional options such as −−ndb−connectstring or −−config−file with −−configinfo serves no purpose. Examples

1. To obtain the node ID and type of each node in the cluster:

$> ./ndb_config −−query=nodeid,type −−fields=':' −−rows='\n'

In this example, we used the −−fields options to separate the ID and type of each node with a colon character (:), and the −−rows options to place the values for each node on a new line in the output.

2. To produce a connection string that can be used by data, SQL, and API nodes to connect to the management server:

$> ./ndb_config −−config−file=usr/local/mysql/cluster−data/config.ini \
−−query=hostname,portnumber −−fields=: −−rows=, −−type=ndb_mgmd

3. This invocation of ndb_config checks only data nodes (using the −−type option), and shows the values for each node's ID and host name, as well as the values set for its DataMemory and DataDir parameters:

$> ./ndb_config −−type=ndbd −−query=nodeid,host,datamemory,datadir −f ' : ' −r '\n'
1 : : 83886080 : /usr/local/mysql/cluster−data
2 : : 83886080 : /usr/local/mysql/cluster−data
3 : : 83886080 : /usr/local/mysql/cluster−data
4 : : 83886080 : /usr/local/mysql/cluster−data

In this example, we used the short options −f and −r for setting the field delimiter and row separator, respectively, as well as the short option −q to pass a list of parameters to be obtained.

4. To exclude results from any host except one in particular, use the −−host option:

$> ./ndb_config −−host= −f : −r '\n' −q id,type

In this example, we also used the short form −q to determine the attributes to be queried.

Similarly, you can limit results to a node with a specific ID using the −−nodeid option.


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For more information, please refer to the MySQL Reference Manual, which may already be installed locally and which is also available online at http://dev.mysql.com/doc/.


Oracle Corporation (http://dev.mysql.com/).