[HIVE-22641] Columns returned in sorted order when show columns query is run with no search pattern.

• Type: Improvement
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.1.0
• Component/s: Hive, HiveServer2
• Labels: pull-request-available
• Assignee: Chiran Ravani
• Reporter: Chiran Ravani
• Created: 12/Dec/19 19:46
• Updated: 26/Dec/20 00:59

Description

In Hive 1.2.1 and 2.0 while displaying columns for a table, it used to return in same order as it was created. for example

create table col_order_test(server_name string, task_name string, partition_name string, start_time string, end_time string, table_owner string, table_name string) stored as orc;
show columns in col_order_test;

+-----------------+--+
|      field      |
+-----------------+--+
| server_name     |
| task_name       |
| partition_name  |
| start_time      |
| end_time        |
| table_owner     |
| table_name      |
+-----------------+--+

For Hive 3 columns are returned in sorted order for the same query, below is output.

create table col_order_test(server_name string, task_name string, partition_name string, start_time string, end_time string, table_owner string, table_name string) stored as orc;
show columns in col_order_test;

+-----------------+
|      field      |
+-----------------+
| end_time        |
| partition_name  |
| server_name     |
| start_time      |
| table_name      |
| table_owner     |
| task_name       |
+-----------------+

Above behavior looks to be changed with the introduction of search column feature as part of Jira HIVE-18373

This behavior change can cause an existing process to fail in a few environments, for example, code to generate the INSERT OVERWRITE in a different manner, which may result in query failure.

I would like to request a community if we can improve the Jira HIVE-18373 by returning column order same as it was created if the search pattern provided by the user is null.

Attaching patch with the change.

Issue Links

• links to: GitHub Pull Request #1585
• links to: PR 1585