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From "ZhangXin (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-21313) Use faster function to prevent copying immutable byte array twice
Date Sun, 24 Feb 2019 07:39:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-21313?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

ZhangXin updated HIVE-21313:
----------------------------
    Description: 
In file ql/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorAssignRow.java

We may find code like this:

```

Text text = (Text) convertTargetWritable;
 if (text == null)

{     text = new Text(); }

text.set(string);
 ((BytesColumnVector) columnVector).setVal(
     batchIndex, text.getBytes(), 0, text.getLength());

```

 

Using `setVal` method can copy the bytes array generated by `text.getBytes()`. This is totally
unnecessary at all. Since the bytes array is immutable, we can just use `setRef` method to
point to the specific  byte array, which will also lower the memory usage.

 

 

 

 

 

  was:
In file ql/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorAssignRow.java

We may find code like this:

```

Text text = (Text) convertTargetWritable;
if (text == null) {
    text = new Text();
}
text.set(string);
((BytesColumnVector) columnVector).setVal(
    batchIndex, text.getBytes(), 0, text.getLength());

```

 

Using `setVal` method can copy the bytes array generated by `text.getBytes()`. This is totally
unnecessary at all. Since the bytes array is immutable, we can just use `setRef` method to
point to the specific  byte array, which will also lower the memory usage.

 

 

 


> Use faster function to prevent copying immutable byte array twice
> -----------------------------------------------------------------
>
>                 Key: HIVE-21313
>                 URL: https://issues.apache.org/jira/browse/HIVE-21313
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: ZhangXin
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> In file ql/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorAssignRow.java
> We may find code like this:
> ```
> Text text = (Text) convertTargetWritable;
>  if (text == null)
> {     text = new Text(); }
> text.set(string);
>  ((BytesColumnVector) columnVector).setVal(
>      batchIndex, text.getBytes(), 0, text.getLength());
> ```
>  
> Using `setVal` method can copy the bytes array generated by `text.getBytes()`. This is
totally unnecessary at all. Since the bytes array is immutable, we can just use `setRef`
method to point to the specific  byte array, which will also lower the memory usage.
>  
>  
>  
>  
>  



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