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From "Liyin Tang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-6032) Port HFileBlockIndex improvement from HBASE-5987
Date Wed, 30 May 2012 21:49:24 GMT

    [ https://issues.apache.org/jira/browse/HBASE-6032?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13286099#comment-13286099
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Liyin Tang commented on HBASE-6032:
-----------------------------------

Thanks Ted for porting HBASE-5987 to trunk !
Some of the static functions in TestHBaseCase are still quite useful. It allows the unit test
play around in the region level.
Maybe we shall move these useful code to HBaseTestingUtility :)
                
> Port HFileBlockIndex improvement from HBASE-5987
> ------------------------------------------------
>
>                 Key: HBASE-6032
>                 URL: https://issues.apache.org/jira/browse/HBASE-6032
>             Project: HBase
>          Issue Type: Task
>            Reporter: Zhihong Yu
>            Assignee: Zhihong Yu
>             Fix For: 0.96.0
>
>         Attachments: 6032-ports-5987-v2.txt, 6032-ports-5987.txt
>
>
> Excerpt from HBASE-5987:
> First, we propose to lookahead for one more block index so that the HFileScanner would
know the start key value of next data block. So if the target key value for the scan(reSeekTo)
is "smaller" than that start kv of next data block, it means the target key value has a very
high possibility in the current data block (if not in current data block, then the start kv
of next data block should be returned. +Indexing on the start key has some defects here+)
and it shall NOT query the HFileBlockIndex in this case. On the contrary, if the target key
value is "bigger", then it shall query the HFileBlockIndex. This improvement shall help to
reduce the hotness of HFileBlockIndex and avoid some unnecessary IdLock Contention or Index
Block Cache lookup.
> This JIRA is to port the fix to HBase trunk, etc.

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