[jira] [Commented] (CASSANDRA-3772) Evaluate Murmur3-based partitioner

["Pavel Yaskevich (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-3772?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13438002#comment-13438002 ] 

Pavel Yaskevich commented on CASSANDRA-3772:
--------------------------------------------

My tests show that Murmur3Partitioner actually is worse than MD5 with high cardinality indexes, here is what I did (kernel 3.0.0-19, 2.2Ghz quad-core Opteron, 2GB RAM):

For each test:

 - wiped all of the data directories and re-compiled with 'clean'
 - ran stress with -c 50 -C 500 -S 512 -n 50000 (where -c is number of columns, -C values cardinality and -S is value size in bytes) 4 times (to make it hot)

RandomPartitioner:  average op rate is 845.
Murmur3Partitioner: average op rage is 721. 



                
> Evaluate Murmur3-based partitioner
> ----------------------------------
>
>                 Key: CASSANDRA-3772
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3772
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Pavel Yaskevich
>             Fix For: 1.3
>
>         Attachments: 0001-CASSANDRA-3772.patch, 0001-CASSANDRA-3772-Test.patch, hashed_partitioner_3.diff, hashed_partitioner.diff, MumPartitionerTest.docx, try_murmur3_2.diff, try_murmur3.diff
>
>
> MD5 is a relatively heavyweight hash to use when we don't need cryptographic qualities, just a good output distribution.  Let's see how much overhead we can save by using Murmur3 instead.

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