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https://issues.apache.org/jira/browse/HIVE-7805?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14307771#comment-14307771
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Nick Dimiduk commented on HIVE-7805:
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Bumping priority for a nice, easy performance gain.
> Support running multiple scans in hbase-handler
> -----------------------------------------------
>
> Key: HIVE-7805
> URL: https://issues.apache.org/jira/browse/HIVE-7805
> Project: Hive
> Issue Type: Improvement
> Components: HBase Handler
> Affects Versions: 0.14.0
> Reporter: Andrew Mains
> Assignee: Andrew Mains
> Attachments: HIVE-7805.1.patch, HIVE-7805.patch
>
>
> Currently, the HiveHBaseTableInputFormat only supports running a single scan.
> This can be less efficient than running multiple disjoint scans in certain
> cases, particularly when using a composite row key. For instance, given a row
> key schema of:
> {code}
> struct<bucket int, time timestamp>
> {code}
> if one wants to push down the predicate:
> {code}
> bucket IN (1, 10, 100) AND timestamp >= 1408333927 AND timestamp < 1408506670
> {code}
> it's much more efficient to run a scan for each bucket over the time range
> (particularly if there's a large amount of data per day). With a single scan,
> the MR job has to process the data for all time for buckets in between 1 and
> 100.
> hive should allow HBaseKeyFactory's to decompose a predicate into one or more
> scans in order to take advantage of this fact.
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