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Date: Tue, 1 May 2012 16:13:50 +0000 (UTC)
From: "Sam Tunnicliffe (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
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Subject: [jira] [Issue Comment Edited] (CASSANDRA-4116) check most recent TS
 values in SSTables when a row tombstone has already been encountered
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    [ https://issues.apache.org/jira/browse/CASSANDRA-4116?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265881#comment-13265881 ] 

Sam Tunnicliffe edited comment on CASSANDRA-4116 at 5/1/12 4:12 PM:
--------------------------------------------------------------------

Updated patches as per comments. In {{collectAllData}}, collect the eligible iterators in a multimap with key = maxTimestamp (I guess that its pretty unlikely for two sstables to have the exact same timestamp, but using a Multimap doesn't really add any cost). Then, if we did find a row tombstone, only keep the iterators from younger sstables. Otherwise, keep all that we collected.
                
      was (Author: beobal):
    Updated patches as per comments. In {code}collectAllData{code}, collect the eligible iterators in a multimap with key = maxTimestamp (I guess that its pretty unlikely for two sstables to have the exact same timestamp, but using a Multimap doesn't really add any cost). Then, if we did find a row tombstone, only keep the iterators from younger sstables. Otherwise, keep all that we collected.
                  
> check most recent TS values in SSTables when a row tombstone has already been encountered
> -----------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-4116
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4116
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Matthew F. Dennis
>            Assignee: Sam Tunnicliffe
>             Fix For: 1.2
>
>         Attachments: v1-0001-CASSANDRA-4116-After-Row-tombstone-skip-earlier-SSTabl.txt, v1-0002-CASSANDRA-4116-Set-SSTable-maxTimestamp-correctly-for-.txt
>
>
> once C* comes across a row tombstone, C* should check the TS on the tombstone against all SSTables.  If the most recent TS in an SST is older than the row tombstone, that entire SST (or the remainder of it) can be safely ignored.
> There are two drivers for this.
> * avoid checking column values that could not possibly be in the result set
> * avoid OOMing because all the tombstones are temporarily kept in memory.

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