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From "Yang Yang (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-3073) liveSize() calculation is wrong in case of overwrite
Date Wed, 24 Aug 2011 00:49:31 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-3073?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Yang Yang updated CASSANDRA-3073:
---------------------------------

    Attachment: 0001-liveSize-is-different-from-throughput-particularly-w.patch

simple fix.

> liveSize() calculation is wrong in case of overwrite
> ----------------------------------------------------
>
>                 Key: CASSANDRA-3073
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3073
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Yang Yang
>            Priority: Minor
>         Attachments: 0001-liveSize-is-different-from-throughput-particularly-w.patch
>
>
> currently liveSize() is the sum of currentThroughput.
> this definition is wrong if most of the operations are overwrite, or counter (which is
essentially overwrite).
> for example, the following code should always keep a single entry in db, with one row,
one cf, one column, and supposedly should have a size of only about 100 bytes.
> connect localhost/9160;  
> create keyspace blah;
> use blah;
> create column family cf2 with memtable_throughput=1024 and memtable_operations=10000
 ;
> set the cassandra.yaml 
> memtable_total_space_in_mb: 20
> to make the error appear faster (but if u set to default, still same issue will appear)
> then we use a simple pycassa  script:
> >>> pool = pycassa.connect('blah')
> >>> mycf = pycassa.ColumnFamily(pool,"cf2");
> >>> for x in range(1,10000000) :
> ...     xx = mycf.insert('key1',{'col1':"{}".format(x)})
> ... 
> you will see sstables being generated with only sizes of a few k, though we set the CF
options to get high SSTable sizes

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