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....@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
