statistics: prioritize low selectivity indexes in ... (#20038) #20154
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zz-jason
changed the title
Selectivity() (#20038)
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cherry-pick #20038 to release-4.0
What problem does this PR solve?
Issue Number: close #19904
Problem Summary:
Optimal index is not chosen when computing selectivity.
What is changed and how it works?
What's Changed:
Consider the selectivity of combined conditions in the greedy search procedure to choose the covering indexes.
How it Works:
Different indexes may indicate that different set of conditions are covered, we should prefer the combined conditions with lower selectivity. The rationale behind is that lower selectivity tends to reflect more functional dependencies between columns.
Related changes
Check List
Tests
Side effects
N/A
Release note
Selectivity()