incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Brian Frank Cooper <coop...@yahoo-inc.com>
Subject RE: Cassandra versus HBase performance study
Date Thu, 04 Feb 2010 03:45:08 GMT
We are using get_range_slice, and the AsciiType comparator. I'll try to run a test with BytesType;
but how much difference do you expect?

I would be interested to know the types of optimizations you are planning. We are trying to
understand how much of the performance results from fundamental design decisions versus how
much results from the fact that the system is still under development.

Thanks!

Brian

-----Original Message-----
From: Jonathan Ellis [mailto:jbellis@gmail.com] 
Sent: Wednesday, February 03, 2010 5:05 PM
To: cassandra-user@incubator.apache.org
Subject: Re: Cassandra versus HBase performance study

We have really obvious optimizations to make there that haven't been
done because the biggest contributors so far are using
RandomPartitioner...

Are you using get_key_range or get_range_slice for scanning?  The
former is even slower and deprecated.

With get_range_slice your comparator matters, BytesType is fastest.

-Jonathan

On Wed, Feb 3, 2010 at 6:45 PM, Brian Frank Cooper
<cooperb@yahoo-inc.com> wrote:
> 0.5 does seem to be significantly faster - the latency is better and it provides significantly
more throughput. I'm updating my charts with new values now.
>
> One thing that is puzzling is the scan performance. The scan experiment is to scan between
1-100 records on each request. My 6 node Cassandra cluster is only getting up to about 230
operations/sec, compared to >1400 ops/sec for other systems. The latency is quite a bit
higher. A chart with these results is here:
>
> http://www.brianfrankcooper.net/pubs/scans.png
>
> Is this the expected performance? I'm using the OrderPreservingPartitioner with InitialToken
values that should evenly partition the data (and the amount of data in /var/cassandra/data
is about the same on all servers). I'm using get_range_slice() from Java (code snippet below).
>
> At the max throughput (230 ops/sec), when latency is over 1.2 sec, CPU usage varies from
~5% to ~72% on different boxes. Disk busy varies from 60% to 90% (and the machine with the
busiest disk is not the one with highest CPU usage.) Network utilization (eth0 %util both
in and out) varies from 15%-40% on different boxes. So clearly there is some imbalance (and
the workload itself is skewed via a Zipfian distribution) but I'm surprised that the latencies
are so high even in this case.
>
> Code snippet - fields is a Set<String> listing the columns I want; recordcount
is the number of records to return.
>
> SlicePredicate predicate;
> if (fields==null)
> {
>        predicate = new SlicePredicate(null,new SliceRange(new byte[0], new byte[0],false,1000000));
> }
> else
> {
>        Vector<byte[]> fieldlist=new Vector<byte[]>();
>        for (String s : fields)
>        {
>                fieldlist.add(s.getBytes("UTF-8"));
>        }
>        predicate = new SlicePredicate(fieldlist,null);
> }
> ColumnParent parent = new ColumnParent("data", null);
>
> List<KeySlice> results = client.get_range_slice(table,parent,predicate,startkey,"",recordcount,ConsistencyLevel.ONE);
>
> Thanks!
>
> Brian
>
> ________________________________________
> From: Brian Frank Cooper
> Sent: Saturday, January 30, 2010 7:56 AM
> To: cassandra-user@incubator.apache.org
> Subject: RE: Cassandra versus HBase performance study
>
> Good idea, we'll benchmark 0.5 next.
>
> brian
>
> -----Original Message-----
> From: Jonathan Ellis [mailto:jbellis@gmail.com]
> Sent: Friday, January 29, 2010 1:13 PM
> To: cassandra-user@incubator.apache.org
> Subject: Re: Cassandra versus HBase performance study
>
> Thanks for posting your results; it is an interesting read and we are
> pleased to beat HBase in most workloads. :)
>
> Since you originally benchmarked 0.4.2, you might be interested in the
> speed gains in 0.5.  A couple graphs here:
> http://spyced.blogspot.com/2010/01/cassandra-05.html
>
> 0.6 (beta in a few weeks?) is looking even better. :)
>
> -Jonathan
>

Mime
View raw message