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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HBASE-4583) Integrate RWCC with Append and Increment operations
Date Sun, 28 Oct 2012 00:11:12 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13485529#comment-13485529
] 

Lars Hofhansl edited comment on HBASE-4583 at 10/28/12 12:09 AM:
-----------------------------------------------------------------

Here's a pretty radical change!

It removes Memstore.upsert completely along with all callers and all tests that were testing
that functionality.

Note that while upsert is no longer needed for *correctness* (it used to set the memstoreTS
to 0 so that other increments/appends would be guaranteed to see the previous values), it
was still a potential performance improvement because stale KVs were removed immediately.

However, this actually used to violate the HBase VERSIONS contract.
TestAtomicOperation.testIncrementMultiThreads is not measurably slower on my machine.

With this patch Increment and Append are no longer special w.r.t. MVCC.

                
      was (Author: lhofhansl):
    Here's a pretty radical change!

It remove Memstore.upsert completely along with all callers and all tests that testing this
functionality.

Note that while upsert is no longer needed for *correctness* (it used to set the memstoreTS
to 0 so that other increments/appends would be guaranteed to see the previous values), it
was still a potential performance improvement because stale KVs were removed immediately.

However, this actually violated the HBase VERSIONS contract.
TestAtomicOperation.testIncrementMultiThreads is not measurably slower on my machine.
                  
> Integrate RWCC with Append and Increment operations
> ---------------------------------------------------
>
>                 Key: HBASE-4583
>                 URL: https://issues.apache.org/jira/browse/HBASE-4583
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>             Fix For: 0.94.3, 0.96.0
>
>         Attachments: 4583-trunk-radical.txt, 4583.txt, 4583-v2.txt, 4583-v3.txt, 4583-v4.txt
>
>
> Currently Increment and Append operations do not work with RWCC and hence a client could
see the results of multiple such operation mixed in the same Get/Scan.
> The semantics might be a bit more interesting here as upsert adds and removes to and
from the memstore.

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