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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-3063) BloomMapFile - fail-fast version of MapFile for sparsely populated key space
Date Sat, 29 Mar 2008 23:05:24 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-3063?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12583379#action_12583379
] 

Hadoop QA commented on HADOOP-3063:
-----------------------------------

-1 overall.  Here are the results of testing the latest attachment 
http://issues.apache.org/jira/secure/attachment/12378873/bloommap-v2.patch
against trunk revision 619744.

    @author +1.  The patch does not contain any @author tags.

    tests included +1.  The patch appears to include 4 new or modified tests.

    javadoc -1.  The javadoc tool appears to have generated 1 warning messages.

    javac -1.  The applied patch generated 579 javac compiler warnings (more than the trunk's
current 568 warnings).

    release audit +1.  The applied patch does not generate any new release audit warnings.

    findbugs -1.  The patch appears to introduce 3 new Findbugs warnings.

    core tests +1.  The patch passed core unit tests.

    contrib tests +1.  The patch passed contrib unit tests.

Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2098/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2098/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2098/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2098/console

This message is automatically generated.

> BloomMapFile - fail-fast version of MapFile for sparsely populated key space
> ----------------------------------------------------------------------------
>
>                 Key: HADOOP-3063
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3063
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: io
>    Affects Versions: 0.17.0
>            Reporter: Andrzej Bialecki 
>         Attachments: bloommap-v2.patch, bloommap.patch
>
>
> The need for this improvement arose when working with large ancillary MapFile-s (essentially
used as external dictionaries). For each invokation of map() / reduce() it was necessary to
perform several look-ups in these MapFile-s, and in case of sparsely populated key-space the
cost of finding that a key is absent was too high.
> This patch implements a subclass of MapFile that creates a Bloom filter from all keys,
so that accurate tests for absence of keys can be performed quickly and with 100% accuracy.
> Writer.append() operations update a DynamicBloomFilter, which is then serialized when
the Writer is closed. This filter is loaded in memory when a Reader is created. Reader.get()
operation first checks the filter for the key membership, and if the key is absent it immediately
returns null without doing any further IO.

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