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https://issues.apache.org/jira/browse/CASSANDRA-7088?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13981156#comment-13981156
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Brandon Williams commented on CASSANDRA-7088:
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My suggestion then is to turn on tracing, which will make it slower, but we'll 
be able to see what's going on post facto.

> Massive performance degradation for TRUNCATE when migrating to 2.0
> ------------------------------------------------------------------
>
>                 Key: CASSANDRA-7088
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7088
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: Linux Mint 16
>            Reporter: Jacek Furmankiewicz
>         Attachments: cassandra.yaml
>
>
> We attempted to migrate our developers to Cassandra 2.0.7 from 1.2.
> Everything worked perfectly, but we have experienced a massive drop in 
> developer velocity.
> We run integration tests with Cucumber BDD and 1000 BDDs went from 7 minutes 
> (Cassandra 1.2) to 15 minutes (2.0.7),
> This is when we run Cassandra of the ramdisk (/dev/shm) to make it run faster 
> on dev boxes.
> When we tried pointed to actual drives  the difference was dramatic: the 
> entire suite took over 70 minutes (!) vs 15 in Cassandra 1.2.
> After investigation, we found that most of the time is spent in the 
> truncation logic between every scenario, where we truncate all the column 
> families and start with a clean DB for the next test case.
> This used to be super fast in 1.2, is now very slow in 2.0.
> It may not seem important, but upgrading to 2.0 has basically cut down 
> developer velocity by 100%, just by more than doubling the time it takes to 
> run our BDD suite.
> We truncate the CFs using the Ruby driver:
>   $cassandra.column_families.each do |column_family|
>         name = column_family[0].to_s
>         $cassandra.truncate! name
>   end
> I am attaching our cassandra.yaml. Please note we already switched off 
> auto_compaction before truncate, just as we did in 1.2 for dev boxes, Made no 
> difference.



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