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From Vladimir Yudovin <vla...@winguzone.com>
Subject Re: Can a Select Count(*) Affect Writes in Cassandra?
Date Thu, 10 Nov 2016 09:02:14 GMT
Hi Shalom,



so not sure, but probably excessive memory consumption by this SELECT causes C* to flush tables
to free memory. 


Best regards, Vladimir Yudovin, 

Winguzone - Hosted Cloud Cassandra
Launch your cluster in minutes.





---- On Thu, 10 Nov 2016 03:36:59 -0500Shalom Sagges &lt;shaloms@liveperson.com&gt;
wrote ----




Hi There!



I'm using C* 2.0.14. 

I experienced a scenario where a "select count(*)" that ran every minute on a table with practically
no results limit (yes, this should definitely be avoided), caused a huge increase in Cassandra
writes to around 150 thousand writes per second for that particular table.



Can anyone explain this behavior? Why would a Select query significantly increase write count
in Cassandra?



Thanks!

 


 
Shalom Sagges
 

 

 
 
 
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