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https://issues.apache.org/jira/browse/HBASE-3996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13050368#comment-13050368
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Eran Kutner commented on HBASE-3996:
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I've added three new classes:
MultiTableInputCollection is a collection of table+scanner pairs that should be
used as input to the mapper.
MultiTableInputFormatBase and MultiTableInputFormat are closely based on the
"non-multi" version with required adaptations.
I've also updated TableMapReduceUtil and TableSplit to support these new
classes.
Usage example:
Scan scan1 = new Scan();
scan1.setStartRow(start1);
scan1.setStopRow(end1);
Scan scan2 = new Scan();
scan2.setStartRow(start2);
scan2.setStopRow(end2);
MultiTableInputCollection mtic = new MultiTableInputCollection();
mtic.Add(tableName1, scan1);
mtic.Add(tableName2, scan2);
TableMapReduceUtil.initTableMapperJob(mtic, TestTableMapper.class,
Text.class, IntWritable.class, job1);
> Support multiple tables and scanners as input to the mapper in map/reduce jobs
> ------------------------------------------------------------------------------
>
> Key: HBASE-3996
> URL: https://issues.apache.org/jira/browse/HBASE-3996
> Project: HBase
> Issue Type: Improvement
> Components: mapreduce
> Reporter: Eran Kutner
> Fix For: 0.90.4
>
> Attachments: MultiTableInputCollection.java,
> MultiTableInputFormat.java, MultiTableInputFormatBase.java,
> TableMapReduceUtil.java, TableSplit.java
>
>
> It seems that in many cases feeding data from multiple tables or multiple
> scanners on a single table can save a lot of time when running map/reduce
> jobs.
> I propose a new MultiTableInputFormat class that would allow doing this.
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