hbase-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Akash Ashok <thehellma...@gmail.com>
Subject Re: Hive+HBase performance is much poorer than Hive+HDFS
Date Wed, 12 Oct 2011 03:17:57 GMT
Hi,
To set this parameter you could use "set hbase.client.scanner.caching=500;"
before the execution of your hive query.

Cheers,
Akash

On Wed, Oct 12, 2011 at 8:34 AM, Weihua JIANG <weihua.jiang@gmail.com>wrote:

> Since I am using Hive to perform query, I don't know how to set it.
> Can you tell me how to do so?
>
> Thanks
> Weihua
>
> 2011/10/12 Jean-Daniel Cryans <jdcryans@apache.org>:
> > This is one big factor and you didn't mention configuring it:
> > http://hbase.apache.org/book.html#perf.hbase.client.caching
> >
> > J-D
> >
> > On Tue, Oct 11, 2011 at 7:47 PM, Weihua JIANG <weihua.jiang@gmail.com
> >wrote:
> >
> >> Hi all,
> >>
> >> I have made some perf test about Hive+HBase. The table is a normal 2D
> >> table with about 160M rows (each row with 7 small columns) and 32
> >> regions. There is only one column family and all regions have been
> >> major compacted to one store file before test.
> >>
> >> On a cluster with 11 task trackers (each with 4 map slots and 1 reduce
> >> slot, these servers also act as region servers), a simple SQL in Hive
> >>   select count(*) from table where column3='Y';
> >> needs ~1700 seconds to finish.
> >>
> >> But, after use CTAS statement to create an internal table (stored as
> >> sequence file), this statement only needs 43 seconds to finish.
> >>
> >> So Hive+HBase is 40X slower than Hive+HDFS.
> >>
> >> Though Hive+HBase has less map tasks (32 vs 223), but since there are
> >> only 44 map slots available, I don't think it is the main cause.
> >>
> >> I studied the source code of HBase scan implementation. To me, it
> >> seems, in my case, the scan performs HFile read in a quite similar way
> >> as sequence file read (sequential reading of each key/value pair). So,
> >> in theory, the performance shall be quite similar.
> >>
> >> Can anyone explain the 40X slowdown?
> >>
> >> Thanks
> >> Weihua
> >>
> >
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message