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From Stephan Ewen <se...@apache.org>
Subject Re: States split over to external storage
Date Fri, 20 Jan 2017 11:25:05 GMT
There are works on different approaches of incremental policies underways
(more soon in some design proposals),
but the point raised here sounded different to me.

Maybe Chen Qin can describe in some more detail what he was having in
mind...

On Fri, Jan 20, 2017 at 12:15 PM, liuxinchun <liuxinchun@huawei.com> wrote:

> I think the current backup strategy checkpoints the while whindow
> everytime,when the window size is very large, it's time and storage
> consuming. An increamental policy should be consided.
>
> Sent from HUAWEI AnyOffice
> *发件人:*Stephan Ewen
> *收件人:*dev@flink.apache.org,
> *抄送:*iuxinchun@huawei.com,Aljoscha Krettek,时金魁,
> *时间:*2017-01-20 18:35:46
> *主题:*Re: States split over to external storage
>
> Hi!
>
> This is an interesting suggestion.
> Just to make sure I understand it correctly: Do you design this for cases
> where the state per machine is larger than that machines memory/disk? And
> in that case, you cannot solve the problem by scaling out (having more
> machines)?
>
> Stephan
>
>
> On Tue, Jan 17, 2017 at 6:29 AM, Chen Qin <cq@uber.com> wrote:
>
> > Hi there,
> >
> > I would like to discuss split over local states to external storage. The
> > use case is NOT another external state backend like HDFS, rather just to
> > expand beyond what local disk/ memory can hold when large key space
> exceeds
> > what task managers could handle. Realizing FLINK-4266 might be hard to
> > tacking all-in-one, I would live give a shot to split-over first.
> >
> > An intuitive approach would be treat HeapStatebackend as LRU cache and
> > split over to external key/value storage when threshold triggered. To
> make
> > this happen, we need minor refactor to runtime and adding set/get logic.
> > One nice thing of keeping HDFS to store snapshots would be avoid
> versioning
> > conflicts. Once checkpoint restore happens, partial write data will be
> > overwritten with previously checkpointed value.
> >
> > Comments?
> >
> > --
> > -Chen Qin
> >
>

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