SAP Note 18969 - Drill-down: COIX overflow KH050

Symptom:

Extent overflow in Table COIX (DBIF_RTAB_SQL_ERROR) KH050

Cause and prerequisites

1. Table settings are incorrect. (in Release 2.1 and 2.2)
2. When you converted the reports from Release 2.1 to 2.2, neither the
report definitions nor the saved data were deleted in COIX.
3. You cannot delete saved report data in CO-PA in Releases 2.2A to
2.2D.
4. Although the data buffering is switched off in batch, the
summarization is updated.
5. Reorganization of saved data and summarization data (2.2 only)
6. Delta read procedure (CO-PA and Release 2.2 only)

Solution
For 1. See notes 12505 and 3502
For 2. See note 12505
For 3. See note 18759
For 4. See note 18976
For 5.
Release 2.2 supports global variables (such as "consecutive period") and variables which are not specified until you execute the report. As a result, report data is saved by combination of variables instead of by report.
In 2.1, the saved data was deleted when you changed the report. In 2.2, you usually reset the variable instead of changing the report. As a result, the report data needs to be reorganized at regular intervals (i.e. every month). (Configuration menu: Reporting -> Reorganization -> Report data.
For 6.:
See notes 21733, 22027 and 22034.