Package org.apache.flink.table.types.logical

Class MultisetType

java.lang.Object
org.apache.flink.table.types.logical.LogicalType
org.apache.flink.table.types.logical.MultisetType
All Implemented Interfaces:
Serializable
@PublicEvolving public final class MultisetType extends LogicalType
Logical type of a multiset (=bag). Unlike a set, it allows for multiple instances for each of its elements with a common subtype. Each unique value (including NULL) is mapped to some multiplicity. There is no restriction of element types; it is the responsibility of the user to ensure uniqueness.

The serialized string representation is MULTISET<t> where t is the logical type of the contained elements. t MULTISET is a synonym for being closer to the SQL standard.

A conversion is possible through a map that assigns each value to an integer multiplicity (Map<t, Integer>).

See Also:

  • Field Details

  • Constructor Details

    • MultisetType

      public MultisetType(boolean isNullable, LogicalType elementType)

    • MultisetType

      public MultisetType(LogicalType elementType)

  • Method Details

    • getElementType

      public LogicalType getElementType()

    • copy

      public LogicalType copy(boolean isNullable)
      Description copied from class: LogicalType
      Returns a deep copy of this type with possibly different nullability.
      Specified by:
      copy in class LogicalType
      Parameters:
      isNullable - the intended nullability of the copied type
      Returns:
      a deep copy

    • asSummaryString

      public String asSummaryString()
      Description copied from class: LogicalType
      Returns a string that summarizes this type for printing to a console. An implementation might shorten long names or skips very specific properties.

      Use LogicalType.asSerializableString() for a type string that fully serializes this instance.

      Overrides:
      asSummaryString in class LogicalType
      Returns:
      summary string of this type for debugging purposes

    • asSerializableString

      public String asSerializableString()
      Description copied from class: LogicalType
      Returns a string that fully serializes this instance. The serialized string can be used for transmitting or persisting a type.

      See LogicalTypeParser for the reverse operation.

      Specified by:
      asSerializableString in class LogicalType
      Returns:
      detailed string for transmission or persistence

    • supportsInputConversion

      public boolean supportsInputConversion(Class<?> clazz)
      Description copied from class: LogicalType
      Returns whether an instance of the given class can be represented as a value of this logical type when entering the table ecosystem. This method helps for the interoperability between JVM-based languages and the relational type system.

      A supported conversion directly maps an input class to a logical type without loss of precision or type widening.

      For example, java.lang.Long or long can be used as input for BIGINT independent of the set nullability.

      Specified by:
      supportsInputConversion in class LogicalType
      Parameters:
      clazz - input class to be converted into this logical type
      Returns:
      flag that indicates if instances of this class can be used as input into the table ecosystem
      See Also:

    • supportsOutputConversion

      public boolean supportsOutputConversion(Class<?> clazz)
      Description copied from class: LogicalType
      Returns whether a value of this logical type can be represented as an instance of the given class when leaving the table ecosystem. This method helps for the interoperability between JVM-based languages and the relational type system.

      A supported conversion directly maps a logical type to an output class without loss of precision or type widening.

      For example, java.lang.Long or long can be used as output for BIGINT if the type is not nullable. If the type is nullable, only java.lang.Long can represent this.

      Specified by:
      supportsOutputConversion in class LogicalType
      Parameters:
      clazz - output class to be converted from this logical type
      Returns:
      flag that indicates if instances of this class can be used as output from the table ecosystem
      See Also:

    • getDefaultConversion

      public Class<?> getDefaultConversion()
      Description copied from class: LogicalType
      Returns the default conversion class. A value of this logical type is expected to be an instance of the given class when entering or is represented as an instance of the given class when leaving the table ecosystem if no other conversion has been specified.

      For example, java.lang.Long is the default input and output for BIGINT.

      Specified by:
      getDefaultConversion in class LogicalType
      Returns:
      default class to represent values of this logical type
      See Also:

    • getChildren

      public List<LogicalType> getChildren()
      Specified by:
      getChildren in class LogicalType

    • accept

      public <R> R accept(LogicalTypeVisitor<R> visitor)
      Specified by:
      accept in class LogicalType

    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class LogicalType

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class LogicalType