[jira] Commented: (HIVE-477) Some optimization thoughts for Hive

["He Yongqiang (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12707194#action_12707194 ] 

He Yongqiang commented on HIVE-477:
-----------------------------------

one refrence for 4):
Breaking the Memory Wall in MonetDB.
And there are also many other references of Array-based execution.

> 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 profiling test, 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 misses, 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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