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Posted to issues@drill.apache.org by "Andy Pernsteiner (JIRA)" <ji...@apache.org> on 2015/06/10 17:57:00 UTC
[jira] [Created] (DRILL-3270) Modify HbaseGroupScan to allow
multiple fragments per region
Andy Pernsteiner created DRILL-3270:
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Summary: Modify HbaseGroupScan to allow multiple fragments per region
Key: DRILL-3270
URL: https://issues.apache.org/jira/browse/DRILL-3270
Project: Apache Drill
Issue Type: Improvement
Components: Query Planning & Optimization, Storage - HBase
Affects Versions: 1.0.0
Reporter: Andy Pernsteiner
Assignee: Jinfeng Ni
Priority: Minor
When performing a full HBASE or MapR-DB table scan using drill, it is observed within the resulting query profile that only one minor fragment is assigned per region, regardless of the size of the region. In the case of extremely large regions, especially if there are regions of mismatching sizes, this can result in poor performance and a low degree of parallelism.
One possible option (mentioned by sphillips) is to lazily compute the splits by assuming that the keys within a given region were evenly distributed (not perfect, but better than nothing), and perhaps have a 'max-frags-per-region' setting.
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