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From "Todd Lipcon (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5241) Deletes should not mask Puts that come after it.
Date Mon, 20 Feb 2012 23:31:34 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5241?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13212214#comment-13212214
] 

Todd Lipcon commented on HBASE-5241:
------------------------------------

{quote}
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.
{quote}

What are the "better semantics" that we would offer? ie, if I do:
- put value "a" at ts=1
- delete at ts=3
- put value "b" at ts=2

and I do a read with "current time" semantics, do you expect to see "b" or nothing? I'm not
convinced that "b" is a "better semantic" here, except for the point that it makes major compaction
more transparent. The transparency of compaction is sort of nice, but compaction is already
not transparent because of time travel reads (except for the "always keep versions" stuff
that we did recently)
                
> 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
>            Assignee: Amitanand Aiyer
>         Attachments: HBASE-5241.D1731.1.patch, HBASE-5241.D1731.2.patch, HBASE-5241.D1731.3.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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