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From "Billy Pearson (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-493) Write-If-Not-Modified-Since support
Date Wed, 02 Jul 2008 20:15:45 GMT

    [ https://issues.apache.org/jira/browse/HBASE-493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12610028#action_12610028

Billy Pearson commented on HBASE-493:

I would like to see this method add if we can get it. This would allow people to use the client
to support updating a column safely in a multi threaded job where the old column value is
needed to make the new value. 
example a counter like Bigtable allows cells to be used as integer counters but with this
type of check on a update the column could be anything not just a integer.
so I will +1 on voting for this.

> Write-If-Not-Modified-Since support
> -----------------------------------
>                 Key: HBASE-493
>                 URL: https://issues.apache.org/jira/browse/HBASE-493
>             Project: Hadoop HBase
>          Issue Type: New Feature
>          Components: client, io, regionserver
>            Reporter: Chris Richard
>            Priority: Minor
> Write-If-Not-Modified-Since for optimistic concurrency control:
> Client retrieves cell (or row) and stores timestamp.
> Client writes to same cell (or row) and passes timestamp.
> If the cell's (or row's) latest timestamp matches the passed timestamp, the write succeeds.
If the timestamps do not match, the write fails and the client is notified. The client must
re-retrieve the cell/row to get the latest timestamp before attempting to write back.
> This behavior would be optional, if the client doesn't pass a timestamp to the write
method, no modified check would be enforced.
> Note: blocked behind HBASE-489 due to requirement that client be able to access timestamp

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