Implement IN-list multi-probing logic for hash joins.
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Key: DERBY-2503
URL: https://issues.apache.org/jira/browse/DERBY-2503
Project: Derby
Issue Type: Improvement
Components: Performance
Affects Versions: 10.3.0.0
Reporter: A B
Priority: Minor
DERBY-47 added a new MultiProbeTableScanResult to handle multi-probing for
nested loop joins, which leads to significant performance improvements for
certain IN-list queries. However, that Jira did not extend the multi-probing
functionality to hash joins. As a result, queries for which the optimizer
chooses to do hash joins cannot currently reap the benefits of IN-list
multi-probing (see DERBY-2500).
It would be good to enhance Derby's execution-time handling of
HashScanResultSets so that it can take advantage of IN-list multi-probing for
hash joins, as well. Doing so would allow Derby to read fewer rows from disk
(similar to DERBY-47) and would also have the convenient side-effect of
decreasing the size of the in-memory hash table.
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