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From Gopalakrishnan R <gopalakrishnan....@gmail.com>
Subject Re: [RELEASE CANDIDATE] Apache Cassandra 1.0.0-rc2 released - Read data inconsistancy
Date Wed, 12 Oct 2011 23:26:18 GMT
I am right now evaluating Cassandra 1.0.0-rc2  with a super column family with 
one super column and variable (from 7 to 18) number of sub columns inside that 
one super column. The column family has about 20 million rows (keys) and about 
200,000 million sub columns (records) in total. I use a 3 node linux cluster 
with replication factor as three and read/write consistancy level as hector 
client default (QUORUM). The column family uses SnappyCompressor and has read 
repair disabled

The issue I face is that when I query the super column for a particular key 
using hector-core-0.8.0-2,
the data retrieved is inconsistent. I mean, for the key that I use to fetch 
data, there are 7 sub columns actually. But the query returns 1 or 3 sub 
columns depending on which nodes respond to it. (I tested by bringing down 
each one of the three nodes in turn).  

When I tried to fetch the data for the same key using cassandra-cli tool, I 
get all the 7 sub columns for both the consistancy levels ONE and QUORUM. 
<b>So is this a inconsistancy issue or compatibility problem between Cassandra 
1.0.0-rc2  and hector-core-0.8.0-2? I tested with same column family and same 
code in Cassandra 1.0.0-beta1 version and it works fine there.</b>

Because I am new to Cassandra and been working with it for only two months I 
paste the code I used to fetch the data below:

                        superColumnQuery = HFactory.createSuperColumnQuery
(keyspaceOperator, 
                                                    stringSerializer, 
stringSerializer, stringSerializer, stringSerializer);
                        superColumnQuery.setColumnFamily(cfName).setKey
(key).setSuperName(scName);
                        result=superColumnQuery.execute();
                        superColumn=result.get();
                        columnList=superColumn.getColumns();

Please suggest me on the problem and the solution.




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