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From "Sergey Shelukhin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-8721) fix for bug that delete can mask puts that happened after the delete was entered
Date Mon, 10 Jun 2013 17:40:21 GMT

    [ https://issues.apache.org/jira/browse/HBASE-8721?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13679668#comment-13679668
] 

Sergey Shelukhin commented on HBASE-8721:
-----------------------------------------

"It will start working again after the major compaction has run" that is not actually correct
afaik.
This will only be true if put is in memstore when major compaction is run, and that is a bug-ish
behavior (compaction doesn't look at memstore).
If put is flushed out before major compaction, it will not reappear, regardless of seqnums.

And yes the behavior where deletes masks later puts with the same ts is expected
                
> fix for bug that delete can mask puts that happened after the delete was entered
> --------------------------------------------------------------------------------
>
>                 Key: HBASE-8721
>                 URL: https://issues.apache.org/jira/browse/HBASE-8721
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver
>            Reporter: Feng Honghua
>         Attachments: HBASE-8721-0.94-V0.patch
>
>
> this fix aims for bug mentioned in http://hbase.apache.org/book.html 5.8.2.1:
> "Deletes mask puts, even puts that happened after the delete was entered. Remember that
a delete writes a tombstone, which only disappears after then next major compaction has run.
Suppose you do a delete of everything <= T. After this you do a new put with a timestamp
<= T. This put, even if it happened after the delete, will be masked by the delete tombstone.
Performing the put will not fail, but when you do a get you will notice the put did have no
effect. It will start working again after the major compaction has run. These issues should
not be a problem if you use always-increasing versions for new puts to a row. But they can
occur even if you do not care about time: just do delete and put immediately after each other,
and there is some chance they happen within the same millisecond."

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