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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-2158) memtable_throughput_in_mb can not support sizes over 2.2 gigs because of an integer overflow.
Date Sun, 13 Feb 2011 14:33:57 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12994105#comment-12994105
] 

Jonathan Ellis commented on CASSANDRA-2158:
-------------------------------------------

While you are correct, you almost certainly shouldn't have throughput set that high, because
if you are tuning things correctly you will hit your operations count limit first for 99.9%
of workloads.

> memtable_throughput_in_mb can not support sizes over 2.2 gigs because of an integer overflow.
> ---------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-2158
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2158
>             Project: Cassandra
>          Issue Type: Bug
>    Affects Versions: 0.7.0
>            Reporter: Eddie
>
> If memtable_throughput_in_mb is set past 2.2 gigs, no errors are thrown.  However, as
soon as data starts being written it is almost immediately being flushed.  Several hundred
SSTables are created in minutes.  I am almost positive that the problem is that when memtable_throughput_in_mb
is being converted into bytes the result is stored in an integer, which is overflowing.
> From memtable.java:
>     private final int THRESHOLD;
>     private final int THRESHOLD_COUNT;
> ...
> this.THRESHOLD = cfs.getMemtableThroughputInMB() * 1024 * 1024;
> this.THRESHOLD_COUNT = (int) (cfs.getMemtableOperationsInMillions() * 1024 * 1024);
> NOTE:
> I also think currentThroughput also needs to be changed from an int to a long.  I'm not
sure if it is as simple as this or if this also is used in other places.

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