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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5336) C* crashes with an OOM error when using the Simba Driver on a very wide table
Date Wed, 13 Mar 2013 13:30:13 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5336?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13601132#comment-13601132
] 

Jonathan Ellis commented on CASSANDRA-5336:
-------------------------------------------

I guess I didn't read very carefully; I assumed that it would be using {{get_count}} on the
Thrift side, which auto-pages to avoid this problem.  If you're going to use get_range_slices,
then as Sylvain says you [which is to say, Simba] need to do your own paging to avoid OOM.
                
> C* crashes with an OOM error when using the Simba Driver on a very wide table
> -----------------------------------------------------------------------------
>
>                 Key: CASSANDRA-5336
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5336
>             Project: Cassandra
>          Issue Type: Bug
>          Components: API
>    Affects Versions: 1.1.6
>         Environment: C* on a Mac with 1GB VM.  Simba ODBC driver
>            Reporter: Steven Lowenthal
>         Attachments: nhanes600-10k.tarZ, thrift.in, thrift.out
>
>
> The Simba driver executes a version of a count(*) query:
> SELECT SUM(1) from nhanes3 having sum(1) > 0.   It uses this format so ODBC returns
a no rows found error if the table is empty.   It translates into a series of get_range_slice
calls which bring back all of the rows, and for every row, it brings back every single column
name.   C* crashes with an OOM in the thrift code.  The table has almost 600 columns of mixed
text and numeric data with many empty values.

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