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From "Bill Mitchell (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-6825) COUNT(*) with WHERE not finding all the matching rows
Date Fri, 07 Mar 2014 21:57:51 GMT
Bill Mitchell created CASSANDRA-6825:
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             Summary: COUNT(*) with WHERE not finding all the matching rows
                 Key: CASSANDRA-6825
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6825
             Project: Cassandra
          Issue Type: Bug
          Components: Core
         Environment: quad core Windows7 x64
Cassandra 2.0.5
            Reporter: Bill Mitchell
         Attachments: selectrowcounts.txt

Investigating another problem, I needed to do COUNT(*) on the several partitions of a table
immediately after a test case ran, and I discovered that count(*) on the full table and on
each of the partitions returned different counts.  

In particular case, SELECT COUNT(*) FROM sr LIMIT 1000000; returned the expected count from
the test 99999 rows.  The composite primary key splits the logical row into six distinct partitions,
and when I issue a query asking for the total across all six partitions, the returned result
is only 83999.  Drilling down, I find that SELECT * from sr WHERE s = 5 AND l = 11 AND partition
= 0; returns 30,000 rows, but a SELECT COUNT(*) with the identical WHERE predicate reports
only 14,000. 

This is failing immediately after running a single small test, such that there are only two
SSTables, sr-jb-1 and sr-jb-2.  Compaction never needed to run.  

In selectrowcounts.txt is a copy of the cqlsh output showing the incorrect count(*) results.



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