[TRAFODION-2321] Fix other issues related to statement reuse and Hive tables in CSEs

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: sql-general
• Assignee: Hans Zeller
• Reporter: Hans Zeller
• Created: 27/Oct/16 21:05
• Updated: 27/Oct/16 21:05

Description

Besides the security issue, there are a few more problems with using Hive tables to materialize common subexpressions:

• Query caching has to be disabled, since we drop the table as a query ends, but a cached query would reference the same dropped table.

• Executor frees resources of a prepared statement, which drops the table. Then the client executes this statement again.

• Issue with query caching and running two queries with identical plans at the same time. They would conflict in the same table.

Dave Birdsall suggested a solution in a comment in PR772: Create a Hive table at runtime for each statement and bind the name of it at runtime as well. This approach would fix all of the issues listed here.