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From "Andrew Mains (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-7805) Support running multiple scans in hbase-handler
Date Wed, 20 Aug 2014 19:56:25 GMT
Andrew Mains created HIVE-7805:
----------------------------------

             Summary: 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


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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