16.4.4.2. The MySQL Cluster connectstring
With the exception of the MySQL Cluster management server
(ndb_mgmd), each node that is part of a
MySQL Cluster requires a connectstring
that points to the management server's location. This
connectstring is used in establishing a connection to the
management server as well as in performing other tasks
depending on the node's role in the cluster. The syntax for a
connectstring is as follows:
<connectstring> :=
[<nodeid-specification>,]<host-specification>[,<host-specification>]
<nodeid-specification> := node_id
<host-specification> := host_name[:port_num]
node_id is an integer larger than 1 which
identifies a node in config.ini.
host_name is a string representing
a valid Internet host name or IP address.
port_num is an integer referring to
a TCP/IP port number.
example 1 (long): "nodeid=2,myhost1:1100,myhost2:1100,192.168.0.3:1200"
example 2 (short): "myhost1"
All nodes will use localhost:1186 as the
default connectstring value if none is provided. If
port_num is omitted from the
connectstring, the default port is 1186. This port should
always be available on the network because it has been
assigned by IANA for this purpose (see
https://www.iana.org/assignments/port-numbers
for details).
By listing multiple
<host-specification> values, it is
possible to designate several redundant management servers. A
cluster node will attempt to contact successive management
servers on each host in the order specified, until a
successful connection has been established.
There are a number of different ways to specify the
connectstring:
Each executable has its own command-line option which
enables specifying the management server at startup. (See
the documentation for the respective executable.)
It is also possible to set the connectstring for all nodes
in the cluster at once by placing it in a
[mysql_cluster] section in the
management server's my.cnf file.
-
For backward compatibility, two other options are
available, using the same syntax:
Set the NDB_CONNECTSTRING environment
variable to contain the connectstring.
Write the connectstring for each executable into a
text file named Ndb.cfg and place
this file in the executable's startup directory.
However, these are now deprecated and should not be used
for new installations.
The recommended method for specifying the connectstring is to
set it on the command line or in the
my.cnf file for each executable.
