Hans Zeller created TRAFODION-2321:
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Summary: Fix other issues related to statement reuse and Hive
tables in CSEs
Key: TRAFODION-2321
URL: https://issues.apache.org/jira/browse/TRAFODION-2321
Project: Apache Trafodion
Issue Type: Sub-task
Components: sql-general
Reporter: Hans Zeller
Assignee: Hans Zeller
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.
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