The first time you run a segmentation policy, the ILM Engine creates a segment for each dimension slice in the data classification, plus a default segment for new transactions and transactions that do not meet the business rule criteria of other segments.

Over a period of time, the default segment becomes larger and database performance degrades. To avoid performance degradation you must periodically create a new default segment, split the current default segment, or create a new non-default segment to move data to. You might also create a new non-default segment if you need to segment data that was previously missed, or to add a new organization to an organization dimension in the segmentation policy.

Before you can create a segment for an implemented segmentation group, you must create a dimension slice to specify the value of the segment. If you applied a data classification that includes a formula to the segmentation group, the ILM Engine creates and populates the dimension slice when you create the segment. If you did not apply a data classification that uses a formula, you must manually create the dimension slice.

Before you create the new segment, decide which method of periodic segment creation to apply to the segmentation group. The method of periodic segment creation determines how the ILM Engine will create segments in the future as the default segment becomes too large or if you need to manually create a new segment. When you create the new segment you can also choose to compress the segment or make it read-only.

You can change the method of periodic segment creation. Before you can change the method of periodic segment creation, you must delete any segments in the group that are generated and not implemented. When you delete a generated segment, you must delete the most-recently generated segment first.