org.apache.calcite.rel.metadata

Interface BuiltInMetadata.ColumnUniqueness

All Superinterfaces:

Metadata

Enclosing class:

BuiltInMetadata

public static interface BuiltInMetadata.ColumnUniqueness
extends Metadata

Metadata about whether a set of columns uniquely identifies a row.

Method Summary

Methods

Modifier and Type	Method and Description
Boolean	areColumnsUnique(ImmutableBitSet columns, boolean ignoreNulls) Determines whether a specified set of columns from a specified relational expression are unique.

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

rel

Method Detail

areColumnsUnique

Boolean areColumnsUnique(ImmutableBitSet columns,
                       boolean ignoreNulls)

Determines whether a specified set of columns from a specified relational expression are unique.

Nulls can be ignored if the relational expression has filtered out null values.

Parameters:

columns - column mask representing the subset of columns for which uniqueness will be determined

ignoreNulls - if true, ignore null values when determining column uniqueness

Returns:

whether the columns are unique, or null if not enough information is available to make that determination