Because no one has implemented it. It would be a welcome addition and
probably not too difficult.
Thanks,
James
On Tue, Jan 10, 2017 at 7:00 AM 程磊 <comnetw...@163.com> wrote:
> 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 }
