[jira] [Commented] (HIVE-7805) Support running multiple scans in hbase-handler

["Nick Dimiduk (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-7805?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14307771#comment-14307771 ] 

Nick Dimiduk commented on HIVE-7805:
------------------------------------

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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