[GitHub] ZhangXinJason opened a new pull request #548: HIVE-21313: Use faster method to prevent copying bytes twice

[GitBox <gi...@apache.org>]

ZhangXinJason opened a new pull request #548: HIVE-21313: Use faster method to prevent copying bytes twice
URL: https://github.com/apache/hive/pull/548
 
 
   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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