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From: Jean-Marc Spaggiari <jean-marc@spaggiari.org>
Date: Mon, 28 Apr 2014 20:56:36 -0400
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 <CAPQV63VVDDd+tiUgpVzA5U5dSptt4TrMEaFcbn4AjV_yY827SQ@mail.gmail.com>
Subject: Re: question about threads count
To: user <user@hbase.apache.org>
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Why do you want to make sure the row is only inserted once? If you insert
the same raw twice the 2nd one will simple overwrite the first one and
HBase will take care of the versions.

regarding the codes fragments, I don't think the autoflush is going to do a
big difference compared to the cost of the check & put...


2014-04-28 20:50 GMT-04:00 Li Li <fancyerii@gmail.com>:

> I must use checkAndPut to ensure a row is only inserted once.
> if I have 1000 checkAndPut,will setAutoFlush(false) useful?
> is there any performance difference of the following two code fragments?
> 1.
>     table.setAutoFlush(false);
>     for(int i=0;i<1000;i++){
>          Put put=...
>          table.checkAndPut(,....put);
>     }
> 2.
>     table.setAutoFlush(true);
>     for(int i=0;i<1000;i++){
>          Put put=...
>          table.checkAndPut(,....put);
>     }
>
> On Tue, Apr 29, 2014 at 8:36 AM, Jean-Marc Spaggiari
> <jean-marc@spaggiari.org> wrote:
> > It depends. Batch a list of puts/gets wll be way faster than checkAndPut,
> > but the result will not be the same... a batch of puts will not do any
> > check...
> >
> >
> > 2014-04-28 20:17 GMT-04:00 Li Li <fancyerii@gmail.com>:
> >
> >> but I have many checkAndPut operations.
> >> will use batch a better solution?
> >>
> >> On Mon, Apr 28, 2014 at 8:01 PM, Jean-Marc Spaggiari
> >> <jean-marc@spaggiari.org> wrote:
> >> > Hi Li Li,
> >> >
> >> > Yes, threads will impact the performances. If you send all you writes
> >> with
> >> > a single thread, a single HBase handler will take care of them, etc.
> >> HBase
> >> > does not provide a single handler for a single client connexion. It's
> >> able
> >> > to handle multiple threads and clients.
> >> >
> >> > However, it also all depends on the way you send your writes. If you
> >> send a
> >> > single puts(<10000>) per seconds, if will not be better to send 10 000
> >> > threads with a single put.
> >> >
> >> > I will recommend you to run some perf tests on your installation to
> find
> >> a
> >> > good number for your configuration.
> >> >
> >> > JM
> >> >
> >> >
> >> > 2014-04-28 6:27 GMT-04:00 Li Li <fancyerii@gmail.com>:
> >> >
> >> >> hi all,
> >> >>    with the same read/write data, will threads count affect
> performance?
> >> >>    e.g. I have 10,000 write request/second. I don't care the order
> very
> >> >> much.
> >> >>    how many writer threads should I use to obtain maximum throughput?
> >> >>
> >>
>

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