Tim Armstrong created IMPALA-8834:
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Summary: Investigate enabling safe version of
OPTIMIZE_PARTITION_KEY_SCANS by default
Key: IMPALA-8834
URL: https://issues.apache.org/jira/browse/IMPALA-8834
Project: IMPALA
Issue Type: Improvement
Components: Backend
Reporter: Tim Armstrong
Assignee: Tim Armstrong
Just an idea I had while updating the docs. We already have the logic in the
planner to determine when a partition key scan has "distinct" semantics - i.e.
you obtain the correct results so long as the scan returns 0 rows for a
partition when there are no rows present, and at least one row when there is a
row present (but the exact number doesn't affect correctness).
We could push this knowledge down into the scan nodes and have them terminate
early. This would be quite efficient if file handles and footers were already
cached and greatly reduce the number of rows flowing through the rest of the
plan.
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