[HIVE-21292] Break up DDLTask - extract Database related operations

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.1.1
• Fix Version/s: 4.0.0-alpha-1
• Component/s: Hive
• Labels: pull-request-available refactor-ddl
• Assignee: Miklos Gergely
• Reporter: Miklos Gergely
• Created: 19/Feb/19 16:37
• Updated: 17/Nov/22 08:55
• Resolved: 28/Feb/19 08:39

Description

DDLTask is a huge class, more than 5000 lines long. The related DDLWork is also a huge class, which has a field for each DDL operation it supports. The goal is to refactor these in order to have everything cut into more handleable classes under the package  org.apache.hadoop.hive.ql.exec.ddl:

• have a separate class for each operation
• have a package for each operation group (database ddl, table ddl, etc), so the amount of classes under a package is more manageable
• make all the requests (DDLDesc subclasses) immutable
• DDLTask should be agnostic to the actual operations
• right now let's ignore the issue of having some operations handled by DDLTask which are not actual DDL operations (lock, unlock, desc...)

In the interim time when there are two DDLTask and DDLWork classes in the code base the new ones in the new package are called DDLTask2 and DDLWork2 thus avoiding the usage of fully qualified class names where both the old and the new classes are in use.

Step #1: extract all the database related operations from the old DDLTask, and move them under the new package. Also create the new internal framework.

Issue Links

• links to: GitHub Pull Request #543