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From "Bill Mitchell (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-6826) Query returns different number of results depending on fetchsize
Date Wed, 12 Mar 2014 21:20:43 GMT


Bill Mitchell commented on CASSANDRA-6826:

Much as I found Sylvain's suggestion plausible, no, it does not explain this problem.  After
installing the Apache Cassandra 2.0.6 build, the first time I tried this, it still failed.

Unfortunately, the problem is data or timing dependent.  After seeing the failure on 2.0.6,
I changed the test case to write all the rows into one partition, and that worked, so I changed
it back to distributing the rows over 6 partitions, and this time that worked, too.  So we
were "lucky" that the first time I tried this, the failure did appear.  

(I should have noticed that CASSANDRA-6748 appeared only when a column was explicitly set
to null.  That was the behavior of my code about two weeks ago, before I discovered the issues
around having a large number of tombstones in a wide row.)  

> Query returns different number of results depending on fetchsize
> ----------------------------------------------------------------
>                 Key: CASSANDRA-6826
>                 URL:
>             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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