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From Ted Yu <yuzhih...@gmail.com>
Subject Re: Scan Sequence
Date Tue, 16 Jan 2018 03:34:48 GMT
bq. to get an suggest range search to client, and do this suggested range
search

Since you're using coprocessor, the coprocessor can act (range search)
using the suggestion and return the result to the client.
There is no need to return intermediate result to client.

BTW using zookeeper for locking is tricky - how do you keep up with region
split / merge ?

FYI

On Mon, Jan 15, 2018 at 7:24 PM, Yang Zhang <zhang.yang.dm@gmail.com> wrote:

>         In fact , I am using coprocessor to Implement geography index. Each
> region will only have part of the Index to index the data that it contained
> . When I try to implement KNN search, only one region will contain the
> index according to the KNN center point. So this region will give an
> suggest of range search to other region(Because other region may also
> contain part of the data in the range search).
>
>         I am using zookeeper to implement the lock, other region will watch
> until they get the suggest. So if region1 is locked and wait for suggest
> ,and by the time region2 will never get the sacn request  and never give an
> suggest, this caused an dead lock.
>
>         In other way, I can search region2 first (by limit the start and
> end)  to get an suggest range search to client, and do this suggested range
> search at the second time. This will work, but It will cost more time.
>
> Any suggest?
>
> Thanks
>
> 2018-01-15 23:49 GMT+08:00 Ted Yu <yuzhihong@gmail.com>:
>
> > bq. need region2 to search fist, because it has my own index.
> >
> > Looks like only some of the regions have your index. Can you tell us more
> > about the characteristics of the region(s) where index would be present.
> >
> > bq. My scan will be blocked for my lock on region1,
> >
> > By 'my' I assume the lock is placed by your (application) code. Since
> hbase
> > wouldn't know that a subsequent region has index (or suggestion) on what
> to
> > scan.
> > Can you give us more detail ?
> >
> > Thanks
> >
> > On Mon, Jan 15, 2018 at 7:42 AM, Yang Zhang <zhang.yang.dm@gmail.com>
> > wrote:
> >
> > > Hello Everyone
> > >
> > >         I want to know If the Scan is send to HBase by sequence? For
> > > example, If I have a table that has two region(region1,region2), and I
> > sent
> > > a Scan() to this Table. This Scan will be send to region1 first and
> until
> > > region1 returned, region2 can get this Scan? So If There are some
> methods
> > > than I can control the sequence?
> > >
> > >       some time I need region2 to search fist, because it has my own
> > index.
> > > Then It will give an suggest to other region about where to search.. I
> am
> > > using zookeeper to do this, But I found that My scan will be blocked
> for
> > my
> > > lock on region1, and region2 who has the suggest, even't can't receive
> > this
> > > scan.
> > >
> > >       Anyone have suggest?
> > >
> > >
> > > Thanks very much
> > >
> >
>

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