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From Jean-Marc Spaggiari <jean-m...@spaggiari.org>
Subject Re: Scan vs Get
Date Wed, 20 May 2015 03:11:02 GMT
I tried to run scan/get/scan/get many times, and always the same pattern.
You can remove the "LIMIT => 1" parameter and you will get the same
performances.

Scan and get without the QC returns in very similar time. 191ms for one,
194ms for the other one.

2015-05-19 23:02 GMT-04:00 Ted Yu <yuzhihong@gmail.com>:

> J-M:
> How many times did you try the pair of queries ?
>
> Since scan was run first, this would give the get query some advantage,
> right ?
>
> Cheers
>
> On Tue, May 19, 2015 at 7:34 PM, Jean-Marc Spaggiari <
> jean-marc@spaggiari.org> wrote:
>
> > Are not Scan and Gets supposed to be almost as fast?
> >
> > I have a pretty small table with 65K lines, few columns (hundred?) trying
> > to go a get and a scan.
> >
> > hbase(main):009:0> scan 'sensors', { COLUMNS =>
> > ['v:f92acb5b-079a-42bc-913a-657f270a3dc1'], STARTROW => '000a', LIMIT =>
> 1
> > }
> > ROW
> > COLUMN+CELL
> >
> >  000a
> > column=v:f92acb5b-079a-42bc-913a-657f270a3dc1, timestamp=1432088038576,
> >
> value=\x08000aHf92acb5b-079a-42bc-913a-657f270a3dc1\x0EFAILURE\x0CNE-858\x
> >
> >
> >
> 140-0000-000\x02\x96\x01SXOAXTPSIUFPPNUCIEVQGCIZHCEJBKGWINHKIHFRHWHNATAHAHQBFRAYLOAMQEGKLNZIFM
> > 000a
> > 1 row(s) in 12.6720 seconds
> >
> > hbase(main):010:0> get 'sensors', '000a', {COLUMN =>
> > 'v:f92acb5b-079a-42bc-913a-657f270a3dc1'}
> > COLUMN
> > CELL
> >
> >  v:f92acb5b-079a-42bc-913a-657f270a3dc1
> timestamp=1432088038576,
> >
> >
> value=\x08000aHf92acb5b-079a-42bc-913a-657f270a3dc1\x0EFAILURE\x0CNE-858\x140-0000-000\x02\x96\x01SXOAXTPSIUFPPNUCIEVQGCI
> >
> > ZHCEJBKGWINHKIHFRHWHNATAHAHQBFRAYLOAMQEGKLNZIFM
> > 000a
> >
> > 1 row(s) in 0.0280 seconds
> >
> >
> > They both return the same result. However, the get returns in 28ms while
> > the scan returns in 12672ms.
> >
> > How come can the scan be that slow? Is it normal? If I remove the QC from
> > the scan, then it takes only 250ms to return all the columns. I think
> > something is not correct.
> >
> > I'm running on 1.0.0-cdh5.4.0 so I guess it's the same for 1.0.x...
> >
> > JM
> >
>

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