asfimport opened a new issue, #275:
URL: https://github.com/apache/arrow-java/issues/275

   For a fixed/variable width vector, each of its data element can be 
represented as an ArrowBufPointer object, which represents a contiguous memory 
segment. This makes many tasks easier and more efficient (without memory copy): 
calculating hash code, comparing values, etc.
   
   This cannot be achieved for complex vectors, because their values often 
reside in more than one contiguous memory regions. However, it can be seen that 
the contiguous memory regions for each data element forms a tree-like 
structure, whose leaf nodes are the contiguous memory regions. For example, a 
data element for a struct vector forms a tree, whose root corresponds to the 
struct vector, while the child vectors corresponds to the child nodes of the 
tree root. 
   
   In this issue, we provide a data structure that represents each data element 
of a vector as a tree, whose leaf nodes are ArrowBufPointers, representing 
contiguous memory regions for the data element. 
   
   With this data structure, many tasks also becomes easier and more efficient: 
calculating hash code, comparing vector elements (ordering & equality). In 
addition, we can do something that could not have been done in the past, like 
placing data elements into a hash table/hash set, etc. 
   
   
   **Reporter**: [Liya Fan](https://issues.apache.org/jira/browse/ARROW-7213) / 
@liyafan82
   #### PRs and other links:
   - [GitHub Pull Request 
apache/arrow#5883](https://github.com/apache/arrow/pull/5883)
   
   <sub>**Note**: *This issue was originally created as 
[ARROW-7213](https://issues.apache.org/jira/browse/ARROW-7213). Please see the 
[migration documentation](https://github.com/apache/arrow/issues/14542) for 
further details.*</sub>


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