Avoid Globally Detached Indexes

In IBM Informix Extended Parallel Server all indexes are detached. If an index fragment on one coserver is associated with data rows on another coserver, the index is globally detached. Otherwise it is locally detached.

Globally detached indexes are, in general, far less efficient than locally detached indexes, and for this reason IBM recommends that you avoid using them. If you would like the server to warn you whenever a globally detached index is created, set the GLOBAL_DETACH_INFORM environment variable to any value before you start your server. Alternatively you can turn this environment variable on or off with the server on-line using the onutil SET command.

For detailed information and examples of fragmentation issues related to indexes and their corresponding tables, see Index Fragmentation Guidelines.