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From "Bryan Beaudreault (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14460) [Perf Regression] Merge of MVCC and SequenceId (HBASE-HBASE-8763) slowed Increments, CheckAndPuts, batch operations
Date Wed, 02 Dec 2015 18:47:11 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15036353#comment-15036353
] 

Bryan Beaudreault commented on HBASE-14460:
-------------------------------------------

Thank you [~stack]. One piece of feedback we have so far on CDAP after only a couple days
using it is that it is installed on a column family and thus requires each CF it is installed
on to have unlimited versions.  We understand why it requires unlimited versions in its current
state to roll up the increments, but this is awful when you have a column which is incremented
in a CF with other non-increment data. All of that other data will have unlimited versions
as well.

If something like CDAP were incorporated into hbase native I imagine there are better ways
to do this roll up. I just wanted to make sure I voiced this as a great thing to improve upon:
in the hbase-native version, we shouldn't need to configure an entire CF to have unlimited
versions if just 1 or 2 columns are being incremented.

Also, the vast majority of our increments are write-only (we don't care about the result at
increment time). But a small handful do care about that value. So having two different versions
(one read-write, one write-only) would be great.

> [Perf Regression] Merge of MVCC and SequenceId (HBASE-HBASE-8763) slowed Increments,
CheckAndPuts, batch operations
> -------------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-14460
>                 URL: https://issues.apache.org/jira/browse/HBASE-14460
>             Project: HBase
>          Issue Type: Bug
>          Components: Performance
>            Reporter: stack
>            Assignee: stack
>            Priority: Critical
>         Attachments: 14460.txt, region_lock.png
>
>
> As reported by 鈴木俊裕 up on the mailing list -- see "Performance degradation between
CDH5.3.1(HBase0.98.6) and CDH5.4.5(HBase1.0.0)" -- our unification of sequenceid and MVCC
slows Increments (and other ops) as the mvcc needs to 'catch up' to our current point before
we can read the last Increment value that we need to update.
> We can say that our Increment is just done wrong, we should just be writing Increments
and summing on read, but checkAndPut as well as batching operations have the same issue. Fix.



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