Why SkipScanFilter can not support OrderBy.REV_ROW_KEY_ORDER_BY?

[程磊]

Hi,when I  read the following code in OrderBy.complie method, in line 160,it 
seems that SkipScanFilter can not support OrderBy.REV_ROW_KEY_ORDER_BY,
SkipScanFilter still could not support OrderBy.REV_ROW_KEY_ORDER_BY now? and 
why? :


155      if (isInRowKeyOrder && tracker.isOrderPreserving()) {
156            if (tracker.isReverse()) {
157                // Don't use reverse scan if we're using a skip scan, as our 
skip scan doesn't support this yet.
158                // REV_ROW_KEY_ORDER_BY scan would not take effect for a 
projected table, so don't return it for such table types.
159                if 
(context.getConnection().getQueryServices().getProps().getBoolean(QueryServices.USE_REVERSE_SCAN_ATTRIB,
 QueryServicesOptions.DEFAULT_USE_REVERSE_SCAN)
160                        && !context.getScanRanges().useSkipScanFilter()
161                        && context.getCurrentTable().getTable().getType() != 
PTableType.PROJECTED
162                        && context.getCurrentTable().getTable().getType() != 
PTableType.SUBQUERY) {
163                    return OrderBy.REV_ROW_KEY_ORDER_BY;
164                }