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From Chen Li <che...@gmail.com>
Subject Re: LIMIT push down doesn't really LIMIT the source op.
Date Wed, 30 Dec 2015 19:09:56 GMT
Maybe Jianfeng and Taewoo can provide some input?

On Sun, Dec 27, 2015 at 5:41 AM, Wail Alkowaileet <wael.y.k@gmail.com> wrote:
> Hi all,
>
> I was working on a large external dataset and when I query something with
> LIMIT clause, I see that the job waits for the
> ExternalDataScanOperatorDescriptor to finish scanning the whole file.
>
> When I looked at the plan, I found that the limit operator described
> in StreamLimitRuntimeFactory.
> The implementation only skips the frames when the limit expression reached
> and it doesn't *finalize/stop* the source operator from pushing frames,
> which halts the overall job.
>
>             public void nextFrame(ByteBuffer buffer) throws
> HyracksDataException {
>                 if (afterLastTuple) {
>                     return; //Accepting frames without appending it to the
> parent operator
>                 }
>
> I think that applied for any source operator.
>
>
>
> --
>
> *Regards,*
> Wail Alkowaileet

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