[
https://issues.apache.org/jira/browse/HBASE-2856?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12900535#action_12900535
]
Pranav Khaitan commented on HBASE-2856:
---------------------------------------
I guess we could fix this by not updating the scanners after a flush.
Currently, after every flush we are notifying the scanners (called as
observers) so that they update their heap. If we do not notify them about the
flush, the scanner wouldn't encounter any inconsistencies. This should solve
the specific problem you discussed above where flushing results in
inconsistency. This seems like an easy change and maintains correctness. The
only drawback is that we are holding some memstore keys for a little longer
which doesn't seem too big of a problem.
> 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).
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
