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https://issues.apache.org/jira/browse/HBASE-8763?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13986354#comment-13986354
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stack commented on HBASE-8763:
------------------------------
(Pardon me; am excited about this one so went back to do some more study...)
So yeah, why do a MutableLong in KV rather than just a volatile? Probably same
in the end... I see you want to get a reference to a KV. You trying to tie a
KV to something else in case the mvcc gets updated?
Maybe this is it:
- newKv.setMvccVersion(kv.getMvccVersion());
+ newKv.setMvccVersion(kv.getMvccVersionReference());
We are cloning. The original gets updated later? You want to make sure clone
is updated too?
Would be cool if we could get rid of this clone one day.
> [BRAINSTORM] Combine MVCC and SeqId
> -----------------------------------
>
> Key: HBASE-8763
> URL: https://issues.apache.org/jira/browse/HBASE-8763
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: Enis Soztutar
> Assignee: Jeffrey Zhong
> Priority: Critical
> Attachments: hbase-8736-poc.patch, hbase-8763-poc-v1.patch,
> hbase-8763_wip1.patch
>
>
> HBASE-8701 and a lot of recent issues include good discussions about mvcc +
> seqId semantics. It seems that having mvcc and the seqId complicates the
> comparator semantics a lot in regards to flush + WAL replay + compactions +
> delete markers and out of order puts.
> Thinking more about it I don't think we need a MVCC write number which is
> different than the seqId. We can keep the MVCC semantics, read point and
> smallest read points intact, but combine mvcc write number and seqId. This
> will allow cleaner semantics + implementation + smaller data files.
> We can do some brainstorming for 0.98. We still have to verify that this
> would be semantically correct, it should be so by my current understanding.
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