[GitHub] [arrow] scampi commented on a change in pull request #6402: ARROW-7831: [Java] do not allocate a new offset buffer if the slice starts at 0 since the relative offset pointer would be unchanged

[GitBox]

scampi commented on a change in pull request #6402:
URL: https://github.com/apache/arrow/pull/6402#discussion_r446429063



##########
File path: 
java/vector/src/main/java/org/apache/arrow/vector/BaseVariableWidthVector.java
##########
@@ -751,55 +757,57 @@ private void splitAndTransferOffsetBuffer(int startIndex, 
int length, BaseVariab
    */
   private void splitAndTransferValidityBuffer(int startIndex, int length,
                                               BaseVariableWidthVector target) {
-    int firstByteSource = BitVectorHelper.byteIndex(startIndex);
-    int lastByteSource = BitVectorHelper.byteIndex(valueCount - 1);
-    int byteSizeTarget = getValidityBufferSizeFromCount(length);
-    int offset = startIndex % 8;
+    if (length <= 0) {

Review comment:
       >  It seems like you're leaving this function with a different number of 
references than the other exit points.
   
   I'm not sure I understand.
   
   Before, the body of the function was contained in a big if: I thought it was 
good to return early for clarity and avoid declaring variables like 
`firstByteSource` or `lastByteSource` for nothing.




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