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From Jean-Marc Spaggiari <jean-m...@spaggiari.org>
Subject Scan vs Get
Date Wed, 20 May 2015 02:34:15 GMT
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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