JingDas created CALCITE-5913:
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Summary: Support to get functional dependency metadata in
RelMetadataQuery
Key: CALCITE-5913
URL: https://issues.apache.org/jira/browse/CALCITE-5913
Project: Calcite
Issue Type: New Feature
Reporter: JingDas
Assignee: JingDas
Functional dependency analysis can be applied to various problems in query
optimization:
selectivity estimation, estimation of (intermediate) result sizes, *order
optimization*
*(in particular sort avoidance),* cost estimation, and various problems in the
area of semantic query optimization, as said in the paper《Exploiting Functional
Dependence in Query Optimization》
In calcite, it may be meta something like 'FunctionalDependency'
BuiltInMetadata as following:
{code:java}
public abstract class BuiltInMetadata {
// ...
public interface FunctionalDependency extends Metadata {
/** Returns whether column is functionally dependent on columns. */
Boolean functionallyDetermine(ImmutableBitSet columns, int column);
}
} {code}
As the book said, functional dependency analysis is a valuable and challenging
work. I think support order optimization
(in particular sort avoidance) by the relevant functional dependency metadata
firstly, and then complete to get functional dependency function step by step.
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