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From Michel Segel <michael_se...@hotmail.com>
Subject Re: About performance issue of Hive/HBase vs Hive/HDFS
Date Wed, 21 Dec 2011 15:21:59 GMT
Hey Bruce, 
There's a bit more... 
Setting up the region size to help minimize the number of regions,  then there is tuning the
GC and also setting up mslabs.

You can check out Todd L.'s blog posts on Cloudera's website. I think he has both topics covered
in blogs.

Doug may also have updated the HBase book too.

Sent from a remote device. Please excuse any typos...

Mike Segel

On Dec 21, 2011, at 7:32 AM, Bruce Bian <weidong.ban@gmail.com> wrote:

> Hi Michel,
> Maybe I missed something, but that's what was said in those two posts and
> also the results I've got so far when I was doing my own tests.
> So as for tuning HBase, after ensuring data locality, using scanner caching
> and turning off block caching, what are other configs I should pay
> attention to, any tips?
> Yeah,I'm happy to give snappy a shot.
> 
> Regards,
> Bruce
> 
> On Wed, Dec 21, 2011 at 8:52 PM, Michel Segel <michael_segel@hotmail.com>wrote:
> 
>> Ok... Just my random thoughts...
>> There definitely is overhead in HBase that doesn't exist when you are
>> doing direct access against a hive table. 4 to 5 times slower? I'd question
>> how you tuned your HBase.
>> 
>> Having said that, I would imagine that there are still some potential
>> improvements that could be done on hive to work better w HBase.
>> Also why LZO and not Snappy?
>> 
>> 
>> Sent from a remote device. Please excuse any typos...
>> 
>> Mike Segel
>> 
>> On Dec 21, 2011, at 1:14 AM, Bruce Bian <weidong.ban@gmail.com> wrote:
>> 
>>> Hi there,
>>> After I read these two posts on the mailing list
>>> 
>> http://search-hadoop.com/m/nVaw59rFlY1/Performance+between+Hive+queries+vs.+Hive+over+HBase+queries&subj=Performance+between+Hive+queries+vs+Hive+over+HBase+queries
>>> 
>> http://search-hadoop.com/m/X1rzQ1QDSaf2/Hive%252BHBase+performance+is+much+poorer+than+Hive%252BHDFS&subj=Hive+HBase+performance+is+much+poorer+than+Hive+HDFS
>>> Seems like a 4~5X performance downgrade of Hive/HBase vs Hive/HDFS is
>>> expected due to hbase built another layer on top of HDFS. If this is the
>>> issue here, is it possible to bypass the HBase layer to read the HFiles
>>> stored on HDFS directly?
>>> Another possibility maybe the fact that for the same table, the storage
>> is
>>> much larger in HBase(around 5X in my test case, both uncompressed)than in
>>> Hive, as hbase stores each KV pair for one column which causes the key to
>>> be repeated several times. But after I tried compress the Hbase table
>> using
>>> LZO(now nearly the same as in hive uncompressed table), there's no
>>> performance gain for queries like select count(*) from xtable;
>>> Is there anyone working on this?Not sure whether I should put this post
>> to
>>> Hive's mailing list but there seems to be no progress on issues like
>>> https://issues.apache.org/jira/browse/HIVE-1231
>>> 
>>> Regards,
>>> Bruce
>> 

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