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From "Vladimir Rodionov (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-12031) Parallel Scanners inside Region
Date Mon, 22 Sep 2014 23:36:35 GMT

    [ https://issues.apache.org/jira/browse/HBASE-12031?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14144039#comment-14144039
] 

Vladimir Rodionov commented on HBASE-12031:
-------------------------------------------

[~tedyu]

{quote}
What are the values held in tmp array ?
{quote}

*values* array is used in a predictor to keep last N skips. When we need to predict next skip,
we copy data from *values* into *tmp*, then sort "tmp" and discard outliers. So this just
a temporary buffer.

> Parallel Scanners inside Region
> -------------------------------
>
>                 Key: HBASE-12031
>                 URL: https://issues.apache.org/jira/browse/HBASE-12031
>             Project: HBase
>          Issue Type: New Feature
>          Components: Performance, Scanners
>    Affects Versions: 0.98.6
>            Reporter: Vladimir Rodionov
>            Assignee: Vladimir Rodionov
>             Fix For: 1.0.0, 2.0.0, 0.98.7, 0.99.1
>
>         Attachments: HBASE-12031.2.patch, HBASE-12031.patch, ParallelScannerDesign.pdf,
hbase-12031-tests.tar.gz
>
>
> This JIRA to improve performance of multiple scanners running on a same region in parallel.
The scenarios where we will get the performance benefits:
> * New TableInputFormat with input splits smaller than HBase Region.
> * Scanning during compaction (Compaction scanner and application scanner over the same
Region).
> Some JIRAs related to this one:
> https://issues.apache.org/jira/browse/HBASE-7336
> https://issues.apache.org/jira/browse/HBASE-5979 



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