17.4.6. ndb_config — Extract MySQL Cluster Configuration Information

This tool extracts current configuration information for data nodes, SQL nodes, and API nodes from one of a number of sources: a MySQL 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.

The following table includes options that are specific to ndb_config. Additional descriptions follow the table. For options common to most MySQL Cluster programs (including ndb_config), see Section 17.4.25, "Options Common to MySQL Cluster Programs — Options Common to MySQL Cluster Programs".

Table 17.14. ndb_config Options and Variables: MySQL Cluster NDB7.3

Format	Description	Added / Removed
`--nodes`	Print node information (DB section) only.	All MySQL 5.6 based releases
`--connections`	Print CONNECTIONS section information only. Cannot be used with --nodes or --system option.	All MySQL 5.6 based releases
`--query=string`, `-q`	One or more query options (attributes)	All MySQL 5.6 based releases
`--host=name`	Specify host	All MySQL 5.6 based releases
`--type=name`	Specify node type	All MySQL 5.6 based releases
`--nodeid`, `--id`	Get configuration of node with this ID	All MySQL 5.6 based releases
`--fields=string`, `-f`	Field separator	All MySQL 5.6 based releases
`--rows=string`, `-r`	Row separator	All MySQL 5.6 based releases
`--config-file=path`	Set the path to config.ini file	All MySQL 5.6 based releases
`--mycnf`	Read configuration data from my.cnf file	All MySQL 5.6 based releases
`-c`	Short form for --ndb-connectstring	All MySQL 5.6 based releases
`--configinfo`	Dumps information about all NDB configuration parameters in text format with default, maximum, and minimum values. Use with --xml to obtain XML output.	All MySQL 5.6 based releases
`--configinfo --xml`	Use --xml with --configinfo to obtain a dump of all NDB configuration parameters in XML format with default, maximum, and minimum values.	All MySQL 5.6 based releases
`--system`	Print SYSTEM section information only. Cannot be used with --nodes or --connections option.	All MySQL 5.6 based releases
`--config_from_node=#`	Obtain configuration data from the node having this ID (must be a data node).	All MySQL 5.6 based releases

--usage, --help, or -?

Command-Line Format	`--help`
	`--usage`
	`-?`

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

--config_from_node=#

Command-Line Format	`--config_from_node=#`
	Permitted Values
	Type	`numeric`
	Default	`none`
	Range	`1 .. 48`

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.)

--version, -V

Command-Line Format	`--version`
	`-V`

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

--ndb-connectstring=connect_string, -c connect_string

Command-Line Format	`--ndb-connectstring=connectstring`
	`--connect-string=connectstring`
	`-c`
	Permitted Values
	Type	`string`
	Default	`localhost:1186`

Specifies the connectstring to use in connecting to the management server. The format for the connectstring is the same as described in Section 17.3.2.3, "The MySQL Cluster Connectstring", and defaults to localhost:1186.

--config-file=path-to-file

Command-Line Format	`--config-file=path`
	Permitted Values
	Type	`file name`
	Default

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.

--mycnf

Command-Line Format	`--mycnf`
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

Read configuration data from the my.cnf file.

--query=query-options, -q query-options

Command-Line Format	`--query=string`
	`-q`
	Permitted Values
	Type	`string`
	Default

This is a comma-delimited list of query options—that is, a list of one or more node attributes to be returned. These include id (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=id,type,indexmemory,datamemory returns the node ID, node type, DataMemory, and IndexMemory for each node.

Note

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.

--host=hostname

Command-Line Format	`--host=name`
	Permitted Values
	Type	`string`
	Default

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

Note

While the hostname localhost usually resolves to the IP address 127.0.0.1, 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 127.0.0.2). In general, for best results, you should use numeric IP addresses for all MySQL Cluster configuration values relating to hosts, or verify that all MySQL Cluster hosts handle localhost in the same fashion.

--id=node_id

--nodeid=node_id

Command-Line Format	`--ndb-nodeid=#`
	Permitted Values
	Type	`numeric`
	Default	`0`

Either of these options can be used to specify the node ID of the node for which configuration information is to be obtained. --nodeid is the preferred form.

--nodes

Command-Line Format	`--nodes`
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

Tells ndb_config to print information from parameters defined in DB sections only. This option cannot be used together with --connections or --system.

--connections

Command-Line Format	`--connections`
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

Tells ndb_config to print CONNECTIONS information only. This option cannot be used together with --nodes or --system.

--system

Command-Line Format	`--system`
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

Tells ndb_config to print SYSTEM information only.

This option cannot be used together with the --nodes or --system options.

--type=node_type

Command-Line Format	`--type=name`
	Permitted Values
	Type	`enumeration`
	Default
	Valid Values	`ndbd`
		`mysqld`
		`ndb_mgmd`

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

--fields=delimiter, -f delimiter

Command-Line Format	`--fields=string`
	`-f`
	Permitted Values
	Type	`string`
	Default

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

Note

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

--rows=separator, -r separator

Command-Line Format	`--rows=string`
	`-r`
	Permitted Values
	Type	`string`
	Default

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

Note

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

--configinfo

The --configinfo option causes ndb_config to dump a list of each MySQL Cluster configuration parameter supported by the MySQL 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
A brief description of the parameter's purpose, effects, and usage
MySQL Cluster release version and build information

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

shell> ndb_config
                    --configinfo****** SYSTEM ******Name (String)Name of system (NDB Cluster)MANDATORYPrimaryMGMNode (Non-negative Integer)Node id of Primary ndb_mgmd(MGM) nodeDefault: 0 (Min: 0, Max: 4294967039)ConfigGenerationNumber (Non-negative Integer)Configuration generation numberDefault: 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)…

--configinfo --xml

Command-Line Format	`--configinfo --xml`
	Permitted Values
	Type	`boolean`
	Default	`false`

You can obtain the output of ndb_config --configinfo as XML by adding the --xml option. A portion of the resulting output is shown in this example:

shell> ndb_config --configinfo
                    --xml<configvariables protocolversion="1" ndbversionstring="5.6.11-ndb-7.3.3"                    ndbversion="458758" ndbversionmajor="7" ndbversionminor="0"                    ndbversionbuild="6">  <section name="SYSTEM">    <param name="Name" comment="Name of system (NDB Cluster)" type="string"              mandatory="true"/>    <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>  <section name="NDBD">    <param name="MaxNoOfSubscriptions"               comment="Max no of subscriptions (default 0 == MaxNoOfTables)"              type="unsigned" default="0" min="0" max="4294967039"/>    <param name="MaxNoOfSubscribers"               comment="Max no of subscribers (default 0 == 2 * MaxNoOfTables)"              type="unsigned" default="0" min="0" max="4294967039"/>    …  </section>  …</configvariables>

Note

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).

Important

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 MySQL Cluster sources when ndb_config was compiled. For this reason, no connection to a running MySQL Cluster or access to a config.ini or my.cnf file is required for these two options.

Combining other ndb_config options (such as --query or --type) with --configinfo or --xml 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 MySQL Cluster or read any files, trying to specify additional options such as --ndb-connectstring or --config-file with --configinfo serves no purpose.

Examples

To obtain the node ID and type of each node in the cluster:
```
shell> ./ndb_config --query=id,type
                    --fields=':' --rows='\n'1:ndbd2:ndbd3:ndbd4:ndbd5:ndb_mgmd6:mysqld7:mysqld8:mysqld9:mysqld
```
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.

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

shell> ./ndb_config
                    --config-file=usr/local/mysql/cluster-data/config.ini \ --query=hostname,portnumber --fields=:
                    --rows=, --type=ndb_mgmd192.168.0.179:1186

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, IndexMemory, and DataDir parameters:

shell> ./ndb_config --type=ndbd
                    --query=id,host,datamemory,indexmemory,datadir -f ' : ' -r '\n'1 : 192.168.0.193 : 83886080 : 18874368 : /usr/local/mysql/cluster-data2 : 192.168.0.112 : 83886080 : 18874368 : /usr/local/mysql/cluster-data3 : 192.168.0.176 : 83886080 : 18874368 : /usr/local/mysql/cluster-data4 : 192.168.0.119 : 83886080 : 18874368 : /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.

To exclude results from any host except one in particular, use the --host option:
```
shell> ./ndb_config --host=192.168.0.176
                    -f : -r '\n' -q id,type3:ndbd5:ndb_mgmd
```
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 --id or --nodeid option.