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https://issues.apache.org/jira/browse/HBASE-4344?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13114332#comment-13114332
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Ted Yu commented on HBASE-4344:
-------------------------------
>From Amit:
Earlier, before this patch, the essential ACID violation was occuring because
some updates
that are *newer* than the Scan's read point got included into the return
because flush+read
allowed them to be considered old.
I don't see that problem anymore.
The current violation for ACID semantics seems from the fact that some updates
that *should* be
included in the return (because the readPoint is further) are not being
included. Looks like there
is some compactions going on, during the run, and I need to investigate to see
if somehow the
updateReaders etc is not including a file that needs to be included.
-------
So the patch is not ready for integration yet.
> Persist memstoreTS to disk
> --------------------------
>
> Key: HBASE-4344
> URL: https://issues.apache.org/jira/browse/HBASE-4344
> Project: HBase
> Issue Type: Sub-task
> Reporter: Amitanand Aiyer
> Assignee: Amitanand Aiyer
> Fix For: 0.89.20100924
>
> Attachments: 4344-v10.txt, 4344-v11.txt, 4344-v2.txt, 4344-v4.txt,
> 4344-v5.txt, 4344-v6.txt, 4344-v7.txt, 4344-v8.txt, 4344-v9.txt, patch-2
>
>
> Atomicity can be achieved in two ways -- (i) by using a multiversion
> concurrency system (MVCC), or (ii) by ensuring that "new" writes do not
> complete, until the "old" reads complete.
> Currently, Memstore uses something along the lines of MVCC (called RWCC for
> read-write-consistency-control). But, this mechanism is not incorporated for
> the key-values written to the disk, as they do not include the memstore TS.
> Let us make the two approaches be similar, by persisting the memstoreTS along
> with the key-value when it is written to the disk.
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