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From "He Yongqiang (JIRA)" <j...@apache.org>
Subject [jira] Created: (HIVE-477) Some optimization thoughts for Hive
Date Thu, 07 May 2009 11:05:30 GMT
Some optimization thoughts for Hive
-----------------------------------

                 Key: HIVE-477
                 URL: https://issues.apache.org/jira/browse/HIVE-477
             Project: Hadoop Hive
          Issue Type: Improvement
            Reporter: He Yongqiang


Before we can start working on Hive-461. I am doing some profiling for hive. And here are
some thoughts for improvements:

minor :
1) add a new HiveText to replace Text. It can avoid byte copy when init LazyString. I have
done a draft one, it shows  ~1% performance gains.
2) let StructObjectInspector's 
    {noformat}
     public List<Object> getStructFieldsDataAsList(Object data);
    {noformat}
to be 
    {noformat}
     public Object[] getStructFieldsDataAsArray(Object data);
    {noformat}

In my profile, it shows some performace gains. but in acutal execution it did not. Anyway,
let it return java array will reduce gc's burden of collection ArrayList

not so minor:
3) split FileSinkOperator's Writer into another Thread. Adding a producer-consumer array as
the bridge between the Operators thread and the Writer thread.
4) the operator stack is kind of deep. In order to avoid instruction cache, and increase the
efficiency data cache. I suggest to let Hive's operator can process an array of rows instead
of processing only one row at a time.

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