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https://issues.apache.org/jira/browse/SOLR-1301?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13841058#comment-13841058
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Mark Miller commented on SOLR-1301:
-----------------------------------
Getting started at the moment might be a bit daunting - to help people get
started, to help with testing, and to help with figuring out what we need to
provide to improve usability, I've started the following GitHub project:
https://github.com/markrmiller/solr-map-reduce-example
It's a script that downloads Hadoop and a nightly build of Solr and then builds
an index via map-reduce and deploys that index to Solr.
For now, it's just for looking - it won't actually work until I make a couple
commits so that the standard example config files will correctly work with the
map-reduce module.
This should lower the barrier to entry for anyone that wants to play with
things and serve as a nice guide for those looking to try this out on a real
cluster.
I'll make the commit(s) I referenced above sometime today later when I wake up.
> Add a Solr contrib that allows for building Solr indexes via Hadoop's
> Map-Reduce.
> ---------------------------------------------------------------------------------
>
> Key: SOLR-1301
> URL: https://issues.apache.org/jira/browse/SOLR-1301
> Project: Solr
> Issue Type: New Feature
> Reporter: Andrzej Bialecki
> Assignee: Mark Miller
> Fix For: 5.0, 4.7
>
> Attachments: README.txt, SOLR-1301-hadoop-0-20.patch,
> SOLR-1301-hadoop-0-20.patch, SOLR-1301-maven-intellij.patch, SOLR-1301.patch,
> SOLR-1301.patch, SOLR-1301.patch, SOLR-1301.patch, SOLR-1301.patch,
> SOLR-1301.patch, SOLR-1301.patch, SOLR-1301.patch, SOLR-1301.patch,
> SOLR-1301.patch, SOLR-1301.patch, SOLR-1301.patch, SOLR-1301.patch,
> SOLR-1301.patch, SOLR-1301.patch, SOLR-1301.patch, SOLR-1301.patch,
> SOLR-1301.patch, SolrRecordWriter.java, commons-logging-1.0.4.jar,
> commons-logging-api-1.0.4.jar, hadoop-0.19.1-core.jar,
> hadoop-0.20.1-core.jar, hadoop-core-0.20.2-cdh3u3.jar, hadoop.patch,
> log4j-1.2.15.jar
>
>
> This patch contains a contrib module that provides distributed indexing
> (using Hadoop) to Solr EmbeddedSolrServer. The idea behind this module is
> twofold:
> * provide an API that is familiar to Hadoop developers, i.e. that of
> OutputFormat
> * avoid unnecessary export and (de)serialization of data maintained on HDFS.
> SolrOutputFormat consumes data produced by reduce tasks directly, without
> storing it in intermediate files. Furthermore, by using an
> EmbeddedSolrServer, the indexing task is split into as many parts as there
> are reducers, and the data to be indexed is not sent over the network.
> Design
> ----------
> Key/value pairs produced by reduce tasks are passed to SolrOutputFormat,
> which in turn uses SolrRecordWriter to write this data. SolrRecordWriter
> instantiates an EmbeddedSolrServer, and it also instantiates an
> implementation of SolrDocumentConverter, which is responsible for turning
> Hadoop (key, value) into a SolrInputDocument. This data is then added to a
> batch, which is periodically submitted to EmbeddedSolrServer. When reduce
> task completes, and the OutputFormat is closed, SolrRecordWriter calls
> commit() and optimize() on the EmbeddedSolrServer.
> The API provides facilities to specify an arbitrary existing solr.home
> directory, from which the conf/ and lib/ files will be taken.
> This process results in the creation of as many partial Solr home directories
> as there were reduce tasks. The output shards are placed in the output
> directory on the default filesystem (e.g. HDFS). Such part-NNNNN directories
> can be used to run N shard servers. Additionally, users can specify the
> number of reduce tasks, in particular 1 reduce task, in which case the output
> will consist of a single shard.
> An example application is provided that processes large CSV files and uses
> this API. It uses a custom CSV processing to avoid (de)serialization overhead.
> This patch relies on hadoop-core-0.19.1.jar - I attached the jar to this
> issue, you should put it in contrib/hadoop/lib.
> Note: the development of this patch was sponsored by an anonymous contributor
> and approved for release under Apache License.
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