You need a strategy to control data distribution if you want to grant useful fragment privileges. One effective strategy is to fragment data records by expression. The round-robin data-record distribution strategy, on the other hand, is not a useful strategy because each new data record is added to the next fragment. A round-robin distribution nullifies any clean method of tracking data distribution and therefore eliminates any real use of fragment authority. Because of this difference between expression-based distribution and round-robin distribution, the GRANT FRAGMENT and REVOKE FRAGMENT statements apply only to tables that have expression-based fragmentation.

When you create a fragmented table, no default fragment authority exists. Use the GRANT FRAGMENT statement to grant insert, update, or delete authority on one or more of the fragments. If you want to grant all three privileges at once, use the ALL keyword of the GRANT FRAGMENT statement. However, you cannot grant fragment privileges by merely naming the table that contains the fragments. You must name the specific fragments.

When you want to revoke insert, update, or delete privileges, use the REVOKE FRAGMENT statement. This statement revokes privileges from one or more users on one or more fragments of a fragmented table. If you want to revoke all privileges that currently exist for a table, you can use the ALL keyword. If you do not specify any fragments in the command, the permissions being revoked apply to all fragments in the table that currently have permissions.

For more information, see the GRANT FRAGMENT, REVOKE FRAGMENT, and SET statements in the IBM Informix: Guide to SQL Syntax.