In earlier versions of Extended Parallel Server, one cogroup was created automatically and managed by the database server, cogroup_all. To distinguish among the three categories of coservers, however, cogroup_all, which still exists, is divided into three new groups, one cogroup for each coserver category, as follows:
This cogroup includes all fully capable coservers. Only coservers in this group can store permanent tables. Fully capable coservers are also members of cogroup_tempdata and cogroup_compdata because they can perform all the functions of the specific-purpose coservers.
This cogroup includes all coservers that can store user-defined temporary tables. If you create a new coserver with the CAPABILITIES parameter and the TEMPDATA keyword, it is assigned to this cogroup. This cogroup also includes fully capable coservers.
This cogroup includes the set of coservers that can manage temporary compute-operator data, such as hash-join overflow, sort work spaces, and so on. If you create a new coserver with the CAPABILITIES parameter and the COMPUTE keyword, it is assigned to this cogroup. This cogroup also includes fully capable coservers.
When you add a specific-purpose coserver, as described in Adding Coservers, the coserver is automatically added to appropriate default cogroups. These cogroups are determined by the capability you assign to the coserver. For example, if you specify COMPUTE capability for a coserver, that coserver belongs to cogroup_compdata and cogroup_all. If you specify both COMPUTE and TEMPDATA capabilities, the coserver belongs to both cogroup_tempdata, cogroup_compdata, and cogroup_all.