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https://issues.apache.org/jira/browse/HBASE-2856?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12900924#action_12900924
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stack commented on HBASE-2856:
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@Ryan Thanks for writing this up. Useful. My thinking is that the extra
ts/version is too much to do just now as we're coming up fast on a 0.90.x. Its
a 0.92.x project I'm thinking especially as I think it'll take a bit of work to
implement it so migration is done at runtime. Also, following on from the
Pranav suggestion, for now, can we not just let the scanner exhaust the current
row only against whatever was in memstore rather than let the scanner run to
the end of the region and then when it reaches the end of the row, then let go
of memstore reference? In other words, only at row junctures update its
memstore/hfile scanner set?
> TestAcidGuarantee broken on trunk
> ----------------------------------
>
> Key: HBASE-2856
> URL: https://issues.apache.org/jira/browse/HBASE-2856
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.89.20100621
> Reporter: ryan rawson
> Assignee: ryan rawson
> Priority: Blocker
> Fix For: 0.90.0
>
>
> TestAcidGuarantee has a test whereby it attempts to read a number of columns
> from a row, and every so often the first column of N is different, when it
> should be the same. This is a bug deep inside the scanner whereby the first
> peek() of a row is done at time T then the rest of the read is done at T+1
> after a flush, thus the memstoreTS data is lost, and previously 'uncommitted'
> data becomes committed and flushed to disk.
> One possible solution is to introduce the memstoreTS (or similarly equivalent
> value) to the HFile thus allowing us to preserve read consistency past
> flushes. Another solution involves fixing the scanners so that peek() is not
> destructive (and thus might return different things at different times alas).
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