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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-10163) CommonMergeJoinOperator calls WritableComparator.get() in the inner loop
Date Tue, 31 Mar 2015 07:41:52 GMT
Gopal V created HIVE-10163:
------------------------------

             Summary: CommonMergeJoinOperator calls WritableComparator.get() in the inner
loop
                 Key: HIVE-10163
                 URL: https://issues.apache.org/jira/browse/HIVE-10163
             Project: Hive
          Issue Type: Bug
          Components: Query Processor
    Affects Versions: 1.2.0
            Reporter: Gopal V


The CommonMergeJoinOperator wastes CPU looking up the correct comparator for each WritableComparable
in each row.

{code}
@SuppressWarnings("rawtypes")
  private int compareKeys(List<Object> k1, List<Object> k2) {
    int ret = 0;
....   
      ret = WritableComparator.get(key_1.getClass()).compare(key_1, key_2);
      if (ret != 0) {
        return ret;
      }
    }
{code}

The slow part of that get() is deep within {{ReflectionUtils.setConf}}, where it tries to
use reflection to set the Comparator config for each row being compared.



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