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From "Lars Hofhansl (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5241) Deletes should not mask Puts that come after it.
Date Thu, 16 Feb 2012 02:44:59 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5241?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13209085#comment-13209085
] 

Lars Hofhansl commented on HBASE-5241:
--------------------------------------

If two things happen at the same time there *is* no right order. The fact that we have limited
timer resolution is not that relevant here.

We just discussed another scenario internally here, were we have application level replicas
of a table. One way to do this is have the client write to two HBase clusters and also have
a catchup background task which copies older (before we started the dual-writing) cells to
the replica. We will use this a lot to catch up standby clusters, etc. This would also not
work any longer.

Anyway, if there are other committers that feel that we need this I won't veto it (but I am
-0.5 on it). And it must configurable without any performance detriment when disabled (i.e.
delete still seeks to the next column). I'd also vote to default off.

Maybe some of the other committers would like to comment? @Stack, @Ted, @Todd?

                
> Deletes should not mask Puts that come after it.
> ------------------------------------------------
>
>                 Key: HBASE-5241
>                 URL: https://issues.apache.org/jira/browse/HBASE-5241
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Amitanand Aiyer
>         Attachments: HBASE-5241.D1731.1.patch
>
>
> Suppose that we have a delete row, and then followed by the put. The delete row
> can mask the put, unless there was a major compaction in between.
> Now that we are flushing the memstoreTS to disk, along with the KVs, we should be able
> to differentiate whether or not the Put happened after the Delete and offer better 
> delete semantics.
> Couldn't find a pre-existing JIRA that already discusses this, so creating one.
> Seems related to https://issues.apache.org/jira/browse/HBASE-2406, but is not quite the
same.

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