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Date: Wed, 18 Jan 2017 22:31:26 +0000 (UTC)
From: "stack (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HBASE-17484) Add non cached version of
 OffheapKV for write path
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archived-at: Wed, 18 Jan 2017 22:31:31 -0000


    [ https://issues.apache.org/jira/browse/HBASE-17484?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15828886#comment-15828886 ] 

stack commented on HBASE-17484:
-------------------------------

Any evidence to present to justify why we should have these new types? We've gone this route a bunch of times in our history adding caching and then undoing it.  The argument is that reading these lengths by parsing offheap bytes is slow?

After this patch, how many versions of KeyValue do we have?

Do we have to have a OffheapKeyValue and Cached... ? Do we have to realize the storage in the Type? Isn't it enough having a ByteBufferCell with it internally doing direct or non-direct?

This looks odd... 	  private static final int FIXED_OVERHEAD =
39	      OffheapKeyValue.FIXED_OVERHEAD + +Bytes.SIZEOF_INT + Bytes.SIZEOF_SHORT;  .... is that a double '+'?


> Add non cached version of OffheapKV for write path
> --------------------------------------------------
>
>                 Key: HBASE-17484
>                 URL: https://issues.apache.org/jira/browse/HBASE-17484
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>    Affects Versions: 2.0.0
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>             Fix For: 2.0.0
>
>         Attachments: HBASE-17484.patch
>
>
> After running lot of different performance tests for various scenarios and with multi threads we thought that is  better to have a version of OffheapKV in write path that does not cache anything and its fixed_overhead is equal to that in KeyValue. 


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