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From "Bill Mitchell (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6826) Query returns different number of results depending on fetchsize
Date Wed, 19 Mar 2014 03:09:43 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6826?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13940106#comment-13940106
] 

Bill Mitchell commented on CASSANDRA-6826:
------------------------------------------

Following Sylvain's suggestion that something about the null's might be affecting the problem,
I tried changing the schema.  On my dual-core laptop, where the final column is null but not
set explicitly null on INSERT, the SELECT * is returning a total of 90000 rows where 100000
are expected.  Changing the name of the column to begin with an a, so the nullable column
is no longer last, the SELECT * is returning a total of 80000 rows, where 100000 are expected.
 If I try the same query from cqlsh, where there is no limit on fetchSize, all the expected
rows are returned.  

So, at least in this one experiment, changing the schema by changing the order of the columns
affected the behavior.  This could, of course, be merely coincidental, some timing issue.
 

> Query returns different number of results depending on fetchsize
> ----------------------------------------------------------------
>
>                 Key: CASSANDRA-6826
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6826
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: quad-core Windows 7 x64, single node cluster
> Cassandra 2.0.5
>            Reporter: Bill Mitchell
>            Assignee: Sylvain Lebresne
>
> I issue a query across the set of partitioned wide rows for one logical row, where s,
l, and partition specify the composite primary key for the row:
> SELECT ec, ea, rd FROM sr WHERE s = ? and partition IN ? and l = ? ALLOW FILTERING;
> If I set fetchSize to only 1000 when the Cluster is configured, the query sometimes does
not return all the results.  In the particular case I am chasing, it returns a total of 98586
rows.  If I increase the fetchsize to 100000, all the 99999 actual rows are returned.  This
suggests there is some problem with fetchsize re-establishing the position on the next segment
of the result set, at least when multiple partitions are being accessed.  



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