Even, The scan probably warmed the cache here. Do the same experiment with a fresh HBase for the scan and the random reads.
J-D On Thu, Jul 9, 2009 at 5:14 AM, Qingyan(Evan) Liu<[email protected]> wrote: > dears, > > I'm fresh to hbase. I just checkout hbase trunk rev-792389, and test its > performance by means of org.apache.hadoop.hbase.PerformanceEvaluation > (Detailed testing results are listed below). It's strange that the scan > speed is as slower as randomRead. I haven't change any configuration > parameters in xml files. Anyone can help me to tune the scan performance? > Thanks a lot. > > Hardware: HP Compaq nx6320, CPU Centrino Duo 2 GHz, 1 GB Memory > OS: ubuntu jaunty 9.04 > Hbase: hadoop HDFS namenode + datanode + hbase master + zookeeper + > regionserver are all on localhost. > Test commands: > $ bin/hbase org.apache.hadoop.hbase.PerformanceEvaluation --rows=50000 > randomWrite 1 > $ bin/hbase org.apache.hadoop.hbase.PerformanceEvaluation --rows=50000 scan > 1 > $ bin/hbase org.apache.hadoop.hbase.PerformanceEvaluation --rows=50000 > randomRead 1 > Test results: > randomWrite, time cost: 6858ms > scan, time cost: 18836ms > randomRead, time cost: 16829ms > > I suppose that the scan speed should be much more faster than randomRead. > However, it isn't. Why? > > sincerely, > Evan >
