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https://issues.apache.org/jira/browse/HBASE-8721?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13688448#comment-13688448
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Lars Hofhansl commented on HBASE-8721:
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I already -1'd this.
Puts and Deletes are timestamped. That timestamp defines a happened-before 
realionship.
With KEEP_DELETED_CELLS enabled for CF this allows for nice as-of-time queries 
as well as idempotent operations. We should not break that.

                
> Deletes can mask puts that happen after the delete
> --------------------------------------------------
>
>                 Key: HBASE-8721
>                 URL: https://issues.apache.org/jira/browse/HBASE-8721
>             Project: HBase
>          Issue Type: Improvement
>          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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