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Posted to commits@cassandra.apache.org by "Sylvain Lebresne (JIRA)" <ji...@apache.org> on 2014/04/01 17:51:31 UTC

[jira] [Commented] (CASSANDRA-6825) COUNT(*) with WHERE not finding all the matching rows

    [ https://issues.apache.org/jira/browse/CASSANDRA-6825?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13956669#comment-13956669 ] 

Sylvain Lebresne commented on CASSANDRA-6825:
---------------------------------------------

[~thobbs] Any insights on what it off in the logic exactly?

> 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, single node cluster
> Cassandra 2.0.5
>            Reporter: Bill Mitchell
>            Assignee: Tyler Hobbs
>             Fix For: 2.0.7, 2.1 beta2
>
>         Attachments: cassandra.log, selectpartitions.zip, selectrowcounts.txt, testdb_1395372407904.zip, testdb_1395372407904.zip
>
>
> 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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