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From "Anastasia Braginsky (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-18056) Change CompactingMemStore in BASIC mode to merge multiple segments in pipeline
Date Sun, 21 May 2017 19:46:04 GMT

    [ https://issues.apache.org/jira/browse/HBASE-18056?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16018964#comment-16018964

Anastasia Braginsky commented on HBASE-18056:

Dear [~anoop.hbase],

I would like to deeply apologize, as it looks like I disregarded your comments, while I didn't
meant to. I saw no answer from you for about 3 days. I have committed this small change, before
you raised your last comment. I didn't see your comment on time. I will make a comment next
time before commit. 

I also just completely didn't see this issue as critical. We already had a long discussion
and long benchmark and agreed about it on HBASE-16417. So happened that our conclusion there
did not yet made it from theory to practice. I was surprised by myself to find this constant
being not 1. I was sure it is already 1. I saw it completely as a technical issue that doesn't
need a discussion (because we already did all the discussions), so I didn't wait for 2 +1.

As it looks like you would like reopen this issue, I would suggest to leave the limit to be
1 for now, but when you finish your tests and present your results, showing any other conclusion
than our, we will just change the constant. What do you think? Or you think this need to be


> Change CompactingMemStore in BASIC mode to merge multiple segments in pipeline
> ------------------------------------------------------------------------------
>                 Key: HBASE-18056
>                 URL: https://issues.apache.org/jira/browse/HBASE-18056
>             Project: HBase
>          Issue Type: Sub-task
>            Reporter: Anastasia Braginsky
>         Attachments: HBASE-18056-V01.patch
> Under HBASE-16417 it was decided that CompactingMemStore in BASIC mode should merge multiple
ImmutableSegments in CompactionPipeline. Basic+Merge actually demonstrated reduction in GC,
alongside improvement in other metrics.
> However, the limit on the number of segments in pipeline is still set to 30. Under this
JIRA it should be changed to 1, as it was tested under HBASE-16417.

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