org.apache.calcite.rel.metadata

Interface BuiltInMetadata.UniqueKeys

All Superinterfaces:

Metadata

All Known Subinterfaces:

BuiltInMetadata.All

Enclosing class:

BuiltInMetadata

public static interface BuiltInMetadata.UniqueKeys
extends Metadata

Metadata about which combinations of columns are unique identifiers.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	BuiltInMetadata.UniqueKeys.Handler Handler API.

Field Summary

Fields

Modifier and Type	Field and Description
static MetadataDef<BuiltInMetadata.UniqueKeys>	DEF

Method Summary

Modifier and Type	Method and Description
Set<ImmutableBitSet>	getUniqueKeys(boolean ignoreNulls) Determines the set of unique minimal keys for this expression.

Methods inherited from interface org.apache.calcite.rel.metadata.Metadata

rel

Field Detail

DEF

static final MetadataDef<BuiltInMetadata.UniqueKeys> DEF

Method Detail

getUniqueKeys

Set<ImmutableBitSet> getUniqueKeys(boolean ignoreNulls)

Determines the set of unique minimal keys for this expression. A key is represented as an ImmutableBitSet, 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)