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https://issues.apache.org/jira/browse/CASSANDRA-14556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16543805#comment-16543805
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ASF GitHub Bot commented on CASSANDRA-14556:
--------------------------------------------

Github user aweisberg commented on a diff in the pull request:

    https://github.com/apache/cassandra/pull/239#discussion_r202486275
  
    --- Diff: conf/cassandra.yaml ---
    @@ -784,6 +784,15 @@ compaction_throughput_mb_per_sec: 16
     # between the sstables, reducing page cache churn and keeping hot rows hot
     sstable_preemptive_open_interval_in_mb: 50
     
    +# When enabled, permits Cassandra to zero copy eligible SSTables between
    --- End diff --
    
    Worth documenting this optimization relies on having sstables that are 
wholly contained in the range being streamed and that configurations like size 
tiered without 6696 won't benefit, and would in fact spend time reading indexes 
checking to see if the optimization applies? Leveled should always benefit from 
this optimization.


> Optimize streaming path in Cassandra
> ------------------------------------
>
>                 Key: CASSANDRA-14556
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14556
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Streaming and Messaging
>            Reporter: Dinesh Joshi
>            Assignee: Dinesh Joshi
>            Priority: Major
>              Labels: Performance
>             Fix For: 4.x
>
>
> During streaming, Cassandra reifies the sstables into objects. This creates 
> unnecessary garbage and slows down the whole streaming process as some 
> sstables can be transferred as a whole file rather than individual 
> partitions. The objective of the ticket is to detect when a whole sstable can 
> be transferred and skip the object reification. We can also use a zero-copy 
> path to avoid bringing data into user-space on both sending and receiving 
> side.



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