[jira] [Created] (CASSANDRA-6289) Murmur3Partitioner doesn't yield proper ownership calculation

["Jackson Chung (JIRA)" <ji...@apache.org>]

Jackson Chung created CASSANDRA-6289:
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             Summary: Murmur3Partitioner doesn't yield proper ownership calculation
                 Key: CASSANDRA-6289
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6289
             Project: Cassandra
          Issue Type: Bug
            Reporter: Jackson Chung


In a new 1.2 install with Murmur3 as default, I setup a test cluster with N=RF=3 for the cluster size and RF for a keyspace

but when I look at the ring output (with the keyspace name), to my surprise it shows RF=2.

Further investigate shows the "total replica" is an addition of the float value from the effectiveOwnership. But that results in < 1 for the setup:
{panel}
#bean is set to org.apache.cassandra.db:type=StorageService
$>run effectiveOwnership Keyspace1
#calling operation effectiveOwnership of mbean org.apache.cassandra.db:type=StorageService
#operation returns: 
\{ 
  /127.0.0.1 = 0.9999989;
  /127.0.0.2 = 0.9999989;
  /127.0.0.3 = 0.9999989;
 \}
{panel}

{panel}
$ ./bin/nodetool -h 0 -p 7100 ring Keyspace1

Datacenter: datacenter1
==========
Replicas: 2

Address    Rack        Status State   Load            Owns                Token                                       
                                                                          3074457345618258602                         
127.0.0.1  rack1       Up     Normal  1.02 GB         100.00%             -9223372036854775808                        
127.0.0.2  rack1       Up     Normal  996.38 MB       100.00%             -3074457345618258603                        
127.0.0.3  rack1       Up     Normal  980.55 MB       100.00%             3074457345618258602 
{panel}

{panel}
Keyspace: Keyspace1:
  Replication Strategy: org.apache.cassandra.locator.SimpleStrategy
  Durable Writes: true
    Options: [replication_factor:3]
{panel}
The println would simply class the float value to int, so i guess that's round down.

When using RandomPartitioner, the effectiveOwnership will return 1.0 

So I guess the real question is, is the Murmur3 calculation correct? Or is it losing precision? If it is correct, then I guess we need to force the float -> int to round up? (is that even the right thing to do?)



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