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https://issues.apache.org/jira/browse/HBASE-15082?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15092358#comment-15092358
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stack commented on HBASE-15082:
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bq. But this is a big change, so I'd say 1.3 is better.
Fine. Could have a 1.3 that comes quickly after 1.2. Means 1.2 has slow
increment/append. Would have to write this up in known issues.
[~ram_krish] and [~anoop.hbase] thanks for taking a look at this big patch. Was
going to post to rb but wanted to get a unit test run in first to see if
basically works. There is a last piece outstanding -- a read uncommitted when
doing the get for an increment/checkAndPut, etc. (was going to check w/
[~lhofhansl]) -- that I need to fill in still.
Let me do the tag iterator you suggest, the isolation propagation, and the nice
find on mvccNum and getReadpoint....
bq. Completed the mvcc and so fwded the readPnt ...So we no longer need persist
the seqId in Cells?
I'd add a check after flush takes update write lock and after it gets its flush
sequenceid to see that mvcc readpt == writept. It should be the case as per
your reasoning. If so, yeah, there should not be a case where an ongoing
scanner is going against a read point that could span memstore and hfile -- so
no need of sequenceid to come in when a read from hfile. Lets check.
I need to write up our new regime; the one that started at hbase-12751 with its
read/write locking on rows.
> Fix merge of MVCC and SequenceID performance regression
> -------------------------------------------------------
>
> Key: HBASE-15082
> URL: https://issues.apache.org/jira/browse/HBASE-15082
> Project: HBase
> Issue Type: Sub-task
> Components: Performance
> Reporter: stack
> Assignee: stack
> Priority: Critical
> Fix For: 2.0.0, 1.2.0, 1.3.0
>
> Attachments: 15082.patch, 15082v2.patch, 15082v2.txt, 15082v3.txt,
> 15082v4.patch, 15082v5.patch, 15082v6.patch, 15082v7.patch
>
>
> This is general fix for increments (appends, checkAnd*) perf-regression
> identified in the parent issue. HBASE-15031 has a narrow fix for branch-1.1
> and branch-1.0.
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