Modifying Cogroups

You might want to modify a cogroup by changing the coservers that it includes. This situation occurs when you add nodes to your platform.

To change the coservers in a cogroup

Use the onutil command-line utility to drop the cogroup.
The following example shows the onutil DROP COGROUP command to drop an accounting cogroup:
```
%onutil
1>DROP COGROUP acctg_group;
Cogroup successfully dropped.
2> QUIT;
```
Edit your ONCONFIG file to define the new coservers.
Add a coserver-specific section to your ONCONFIG file for each new coserver. For example, the following excerpt from the ONCONFIG file shows sample values that you might use to define new coservers:
```
COSERVER               9
   NODE         bear9
   ...
END
...
COSERVER               16
   NODE         bear16
   ...
END
```
For more information about the COSERVER and NODE configuration parameters, see the IBM Informix: Administrator's Reference.
Use the onutil command-line utility to create the modified cogroup.
The following example shows onutil running with interactive input. The input is the onutil CREATE COGROUP command to create a cogroup that includes the first 12 coservers in the preceding sample ONCONFIG file.
```
%onutil
1> CREATE COGROUP acctg FROM eds.%r(1..12);
Cogroup successfully created.
2> QUIT;
```
This example substitutes the coserver number for the %r formatting character in the coserver name in the FROM clause.

This example assumes that you defined your dbservername as eds in your ONCONFIG file. Therefore, this example creates a cogroup that includes the following coservers:
```
eds.1
eds.2
eds.3
eds.4
eds.5
eds.6
eds.7
eds.8
eds.9
eds.10
eds.11
eds.12
```
For more information about coserver names, the onutil CREATE COGROUP command, and the use of formatting characters, see the utilities chapter in the IBM Informix: Administrator's Reference.