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https://issues.apache.org/jira/browse/SPARK-25354?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Apache Spark reassigned SPARK-25354:
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    Assignee: Apache Spark

> Parquet vectorized record reader has unneeded operation in several methods
> --------------------------------------------------------------------------
>
>                 Key: SPARK-25354
>                 URL: https://issues.apache.org/jira/browse/SPARK-25354
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 2.4.0
>            Reporter: SongYadong
>            Assignee: Apache Spark
>            Priority: Major
>   Original Estimate: 6h
>  Remaining Estimate: 6h
>
> VectorizedParquetRecordReader class has unneeded operation in nextKeyValue 
> method and other functions called from it:
> 1. In nextKeyValue() method, we call resultBatch() for only initializing a 
> columnar batch if not initialized, not for a return of columnar batch. so we 
> can move initBatch() operation to nextBatch();
> 2. In nextBatch() method, we need not reset columnVectors every time. When 
> rowsReturned >= totalRowCount, function return, reset cost is vasted. so we 
> can put "if (rowsReturned >= totalRowCount) return false;" before 
> columnVectors reset for performance.
> 3. In nextBatch() method, we need not call checkEndOfRowGroup() every time. 
> When rowsReturned != totalCountLoadedSoFar is true, checkEndOfRowGroup do 
> nothing but just return, so we can call checkEndOfRowGroup only when 
> rowsReturned == totalCountLoadedSoFar for reducing function calling.
> 4. In checkEndOfRowGroup() function, we need not get columns of 
> requestedSchema every time. we can get columns only for the first time and 
> save it for future use for performance.
> Accoring to analysis of spark application with JMC tool, we found parquet 
> vectorized record reader call nextKeyValue() and subsequent function very 
> very frequent, performance gains from optimizition of this process is worth 
> to do.



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