Matt McCline created HIVE-18600:
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Summary: Vectorization: Top-Level Vector Expression Scratch Column
Deallocation
Key: HIVE-18600
URL: https://issues.apache.org/jira/browse/HIVE-18600
Project: Hive
Issue Type: Bug
Components: Hive
Reporter: Matt McCline
Assignee: Matt McCline
Fix For: 3.0.0
The operators create various vector expression *arrays* for predicates, SELECT
clauses, key expressions, etc. We could have those be marked as special "top
level" vector expression then we could defer deallocation until the top level
expression is complete. This could be a simple solution that avoids trying fix
our current eager deallocation that tries to reuse scratch columns as soon as
possible. It *isn't optimal*, but it *shouldn't be too bad*. This solution is
much better than not deallocating at all - especially for queries that SELECT a
large number of columns or have a lot of expressions in the operator tree.
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