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https://issues.apache.org/jira/browse/CASSANDRA-12668?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15504919#comment-15504919
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sankalp kohli edited comment on CASSANDRA-12668 at 9/19/16 10:48 PM:
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"Lower throughput != unusable"
The cluster was working in 2.0 and is no longer working in 2.1. That is
unusable. Applications needs a certain throughput otherwise they will have ever
increasing backlog.
"Everything is about trade-offs, as was the swapping of the data structure in
the first place. There's rarely a 100% free lunch."
The tradeoff where a use case is made unusable is not a trade off we should
make. Is there any warning in NEWS.txt which says this tradeoff is made?
"Just some fairly broad qualitative/correlative statements."
These are not statements but practical experience with a cluster which has been
made unusable in 2.1. I will give out more information that you are asking.
was (Author: kohlisankalp):
"Lower throughput != unusable"
The cluster was working in 2.0 and is no longer working in 2.1. That is
unusable. Applications needs a certain throughput otherwise they will have ever
increasing backlog.
"Everything is about trade-offs, as was the swapping of the data structure in
the first place. There's rarely a 100% free lunch."
The tradeoff where a use case is made unusable is not a trade off we should
make.
"Just some fairly broad qualitative/correlative statements."
These are not statements but practical experience with a cluster which has been
made unusable in 2.1. I will give out more information that you are asking.
> Memtable Contention in 2.1
> --------------------------
>
> Key: CASSANDRA-12668
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12668
> Project: Cassandra
> Issue Type: Bug
> Reporter: sankalp kohli
>
> We added a new Btree implementation in 2.1 which causes write performance to
> go down in Cassandra if there is lot of contention in the memtable for a CQL
> partition. Upgrading a cluster from 2.0 to 2.1 with contention causes the
> cluster to fall apart due to GC. We tried making the defaults added in
> CASSANDRA-7546 configurable but that did not help. Is there anyway to fix
> this issue?
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