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From Віталій Тимчишин <tiv...@gmail.com>
Subject Re: Prevent queries from OOM nodes
Date Wed, 26 Sep 2012 08:26:00 GMT
Actually an easy way to put cassandra down is
select count(*) from A limit 10000000
CQL will read everything into List to make latter a count.

2012/9/26 aaron morton <aaron@thelastpickle.com>

> Can you provide some information on the queries and the size of the data
> they traversed ?
>
> The default maximum size for a single thrift message is 16MB, was it
> larger than that ?
> https://github.com/apache/cassandra/blob/trunk/conf/cassandra.yaml#L375
>
> Cheers
>
>
> On 25/09/2012, at 8:33 AM, Bryce Godfrey <Bryce.Godfrey@azaleos.com>
> wrote:
>
> Is there anything I can do on the configuration side to prevent nodes from
> going OOM due to queries that will read large amounts of data and exceed
> the heap available? ****
> ** **
> For the past few days of we had some nodes consistently freezing/crashing
> with OOM.  We got a heap dump into MAT and figured out the nodes were dying
> due to some queries for a few extremely large data sets.  Tracked it back
> to an app that just didn’t prevent users from doing these large queries,
> but it seems like Cassandra could be smart enough to guard against this
> type of thing?****
> ** **
> Basically some kind of setting like “if the data to satisfy query >
> available heap then throw an error to the caller and about query”.  I would
> much rather return errors to clients then crash a node, as the error is
> easier to track down that way and resolve.****
> ** **
> Thanks.****
>
>
>


-- 
Best regards,
 Vitalii Tymchyshyn

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