[jira] [Commented] (HBASE-9272) A parallel, unordered scanner

["Hadoop QA (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-9272?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13791238#comment-13791238 ] 

Hadoop QA commented on HBASE-9272:
----------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12607740/9272-trunk-v3.txt
  against trunk revision .

    {color:green}+1 @author{color}.  The patch does not contain any @author tags.

    {color:red}-1 tests included{color}.  The patch doesn't appear to include any new or modified tests.
                        Please justify why no new tests are needed for this patch.
                        Also please list what manual steps were performed to verify this patch.

    {color:green}+1 hadoop1.0{color}.  The patch compiles against the hadoop 1.0 profile.

    {color:green}+1 hadoop2.0{color}.  The patch compiles against the hadoop 2.0 profile.

    {color:green}+1 javadoc{color}.  The javadoc tool did not generate any warning messages.

    {color:green}+1 javac{color}.  The applied patch does not increase the total number of javac compiler warnings.

    {color:red}-1 findbugs{color}.  The patch appears to cause Findbugs (version 1.3.9) to fail.

    {color:green}+1 release audit{color}.  The applied patch does not increase the total number of release audit warnings.

    {color:green}+1 lineLengths{color}.  The patch does not introduce lines longer than 100

    {color:red}-1 site{color}.  The patch appears to cause mvn site goal to fail.

     {color:red}-1 core tests{color}.  The patch failed these unit tests:
                       org.apache.hadoop.hbase.coprocessor.TestRegionObserverScannerOpenHook

Test results: https://builds.apache.org/job/PreCommit-HBASE-Build/7512//testReport/
Console output: https://builds.apache.org/job/PreCommit-HBASE-Build/7512//console

This message is automatically generated.

> A parallel, unordered scanner
> -----------------------------
>
>                 Key: HBASE-9272
>                 URL: https://issues.apache.org/jira/browse/HBASE-9272
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>            Priority: Minor
>         Attachments: 9272-0.94.txt, 9272-0.94-v2.txt, 9272-0.94-v3.txt, 9272-0.94-v4.txt, 9272-trunk.txt, 9272-trunk-v2.txt, 9272-trunk-v3.txt, ParallelClientScanner.java, ParallelClientScanner.java
>
>
> The contract of ClientScanner is to return rows in sort order. That limits the order in which region can be scanned.
> I propose a simple ParallelScanner that does not have this requirement and queries regions in parallel, return whatever gets returned first.
> This is generally useful for scans that filter a lot of data on the server, or in cases where the client can very quickly react to the returned data.
> I have a simple prototype (doesn't do error handling right, and might be a bit heavy on the synchronization side - it used a BlockingQueue to hand data between the client using the scanner and the threads doing the scanning, it also could potentially starve some scanners long enugh to time out at the server).
> On the plus side, it's only a 130 lines of code. :)



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