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Date: Thu, 2 Jan 2014 13:43:16 -0800
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 <CAHXxaiBLsas9UbvDPDB-mpYp-pVn-e2VFTsYsM0LAx-5PV-97w@mail.gmail.com>
Subject: Re: Performance between HBaseClient scan and HFileReaderV2
From: Sergey Shelukhin <sergey@hortonworks.com>
To: "user@hbase.apache.org" <user@hbase.apache.org>
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Er, using MR over snapshots, which reads files directly...
https://issues.apache.org/jira/browse/HBASE-8369
However, it was only committed to 98.
There was interest in 94 port (HBASE-10076), but it never happened...


On Thu, Jan 2, 2014 at 1:42 PM, Sergey Shelukhin <sergey@hortonworks.com>wrote:

> You might be interested in using
> https://issues.apache.org/jira/browse/HBASE-8369
> However, it was only committed to 98.
> There was interest in 94 port (HBASE-10076), but it never happened...
>
>
> On Thu, Jan 2, 2014 at 1:32 PM, Jerry Lam <chilinglam@gmail.com> wrote:
>
>> Hello Vladimir,
>>
>> In my use case, I guarantee that a major compaction is executed before any
>> scan happens because the system we build is a read only system. There will
>> have no deleted cells. Additionally, I only need to read from a single
>> column family and therefore I don't need to access multiple HFiles.
>>
>> Filter conditions are nice to have because if I can read HFile 8x faster
>> than using HBaseClient, I can do the filter on the client side and still
>> perform faster than using HBaseClient.
>>
>> Thank you for your input!
>>
>> Jerry
>>
>>
>>
>> On Thu, Jan 2, 2014 at 1:30 PM, Vladimir Rodionov
>> <vrodionov@carrieriq.com>wrote:
>>
>> > HBase scanner MUST guarantee correct order of KeyValues (coming from
>> > different HFile's),
>> > filter condition+ filter condition on included column families and
>> > qualifiers, time range, max versions and correctly process deleted
>> cells.
>> > Direct HFileReader does nothing from the above list.
>> >
>> > Best regards,
>> > Vladimir Rodionov
>> > Principal Platform Engineer
>> > Carrier IQ, www.carrieriq.com
>> > e-mail: vrodionov@carrieriq.com
>> >
>> > ________________________________________
>> > From: Jerry Lam [chilinglam@gmail.com]
>> > Sent: Thursday, January 02, 2014 7:56 AM
>> > To: user
>> > Subject: Re: Performance between HBaseClient scan and HFileReaderV2
>> >
>> > Hi Tom,
>> >
>> > Good point. Note that I also ran the HBaseClient performance test
>> several
>> > times (as you can see from the chart). The caching should also benefit
>> the
>> > second time I ran the HBaseClient performance test not just benefitting
>> the
>> > HFileReaderV2 test.
>> >
>> > I still don't understand what makes the HBaseClient performs so poorly
>> in
>> > comparison to access directly HDFS. I can understand maybe a factor of 2
>> > (even that it is too much) but a factor of 8 is quite unreasonable.
>> >
>> > Any hint?
>> >
>> > Jerry
>> >
>> >
>> >
>> > On Sun, Dec 29, 2013 at 9:09 PM, Tom Hood <tom.w.hood@gmail.com> wrote:
>> >
>> > > I'm also new to HBase and am not familiar with HFileReaderV2.
>>  However,
>> > in
>> > > your description, you didn't mention anything about clearing the
>> linux OS
>> > > cache between tests.  That might be why you're seeing the big
>> difference
>> > if
>> > > you ran the HBaseClient test first, it may have warmed the OS cache
>> and
>> > > then HFileReaderV2 benefited from it.  Just a guess...
>> > >
>> > > -- Tom
>> > >
>> > >
>> > >
>> > > On Mon, Dec 23, 2013 at 12:18 PM, Jerry Lam <chilinglam@gmail.com>
>> > wrote:
>> > >
>> > > > Hello HBase users,
>> > > >
>> > > > I just ran a very simple performance test and would like to see if
>> > what I
>> > > > experienced make sense.
>> > > >
>> > > > The experiment is as follows:
>> > > > - I filled a hbase region with 700MB data (each row has roughly 45
>> > > columns
>> > > > and the size is 20KB for the entire row)
>> > > > - I configured the region to hold 4GB (therefore no split occurs)
>> > > > - I ran compactions after the data is loaded and make sure that
>> there
>> > is
>> > > > only 1 region in the table under test.
>> > > > - No other table exists in the hbase cluster because this is a DEV
>> > > > environment
>> > > > - I'm using HBase 0.92.1
>> > > >
>> > > > The test is very basic. I use HBaseClient to scan the entire region
>> to
>> > > > retrieve all rows and all columns in the table, just iterating all
>> > > KeyValue
>> > > > pairs until it is done. It took about 1 minute 22 sec to complete.
>> > (Note
>> > > > that I disable block cache and uses caching size about 10000).
>> > > >
>> > > > I ran another test using HFileReaderV2 and scan the entire region to
>> > > > retrieve all rows and all columns, just iterating all keyValue pairs
>> > > until
>> > > > it is done. It took 11 sec.
>> > > >
>> > > > The performance difference is dramatic (almost 8 times faster using
>> > > > HFileReaderV2).
>> > > >
>> > > > I want to know why the difference is so big or I didn't configure
>> HBase
>> > > > properly. From this experiment, HDFS can deliver the data
>> efficiently
>> > so
>> > > it
>> > > > is not the bottleneck.
>> > > >
>> > > > Any help is appreciated!
>> > > >
>> > > > Jerry
>> > > >
>> > > >
>> > >
>> >
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>> >
>>
>
>

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