Package org.apache.calcite.rel.metadata
Interface BuiltInMetadata.UniqueKeys
- All Superinterfaces:
Metadata
- Enclosing class:
- BuiltInMetadata
Metadata about which combinations of columns are unique identifiers.
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Nested Class Summary
Nested ClassesModifier and TypeInterfaceDescriptionstatic interface
Handler API. -
Field Summary
Fields -
Method Summary
Modifier and TypeMethodDescription@Nullable Set<ImmutableBitSet>
getUniqueKeys
(boolean ignoreNulls) Determines the set of unique minimal keys for this expression.
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Field Details
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DEF
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Method Details
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getUniqueKeys
Determines the set of unique minimal keys for this expression. A key is represented as anImmutableBitSet
, where each bit position represents a 0-based output column ordinal.Nulls can be ignored if the relational expression has filtered out null values.
- Parameters:
ignoreNulls
- if true, ignore null values when determining whether the keys are unique- Returns:
- set of keys, or null if this information cannot be determined (whereas empty set indicates definitely no keys at all)
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