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From James Taylor <jamestay...@apache.org>
Subject Re: Why SkipScanFilter can not support OrderBy.REV_ROW_KEY_ORDER_BY?
Date Tue, 10 Jan 2017 15:47:08 GMT
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 <comnetwork@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                }

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