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...
On Dec 21, 2011, at 1:14 AM, Bruce Bian <[EMAIL PROTECTED]> wrote:
> Hi there,
> After I read these two posts on the mailing list
> 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