Package org.apache.calcite.rel.type

Interface RelDataTypeFactory

All Known Subinterfaces:
JavaTypeFactory
All Known Implementing Classes:
JavaTypeFactoryExtImpl, JavaTypeFactoryImpl, RelDataTypeFactoryImpl, SqlTypeFactoryImpl
public interface RelDataTypeFactory
RelDataTypeFactory is a factory for datatype descriptors. It defines methods for instantiating and combining SQL, Java, and collection types. The factory also provides methods for return type inference for arithmetic in cases where SQL 2003 is implementation defined or impractical.

This interface is an example of the abstract factory pattern. Any implementation of RelDataTypeFactory must ensure that type objects are canonical: two types are equal if and only if they are represented by the same Java object. This reduces memory consumption and comparison cost.

  • Method Details

    • getTypeSystem

      RelDataTypeSystem getTypeSystem()
      Returns the type system.
      Returns:
      Type system

    • createJavaType

      RelDataType createJavaType(Class clazz)
      Creates a type that corresponds to a Java class.
      Parameters:
      clazz - the Java class used to define the type
      Returns:
      canonical Java type descriptor

    • createJoinType

      RelDataType createJoinType(RelDataType... types)
      Creates a cartesian product type.
      Parameters:
      types - array of types to be joined
      Returns:
      canonical join type descriptor

    • createStructType

      RelDataType createStructType(StructKind kind, List<RelDataType> typeList, List<String> fieldNameList)
      Creates a type that represents a structured collection of fields, given lists of the names and types of the fields.
      Parameters:
      kind - Name resolution policy
      typeList - types of the fields
      fieldNameList - names of the fields
      Returns:
      canonical struct type descriptor

    • createStructType

      RelDataType createStructType(List<RelDataType> typeList, List<String> fieldNameList)
      Creates a type that represents a structured collection of fields. Shorthand for createStructType(StructKind.FULLY_QUALIFIED, typeList, fieldNameList).

    • createStructType

      @Deprecated RelDataType createStructType(RelDataTypeFactory.FieldInfo fieldInfo)
      Deprecated.
      Creates a type that represents a structured collection of fields, obtaining the field information via a callback.
      Parameters:
      fieldInfo - callback for field information
      Returns:
      canonical struct type descriptor

    • createStructType

      RelDataType createStructType(List<? extends Map.Entry<String,RelDataType>> fieldList)
      Creates a type that represents a structured collection of fieldList, obtaining the field information from a list of (name, type) pairs.
      Parameters:
      fieldList - List of (name, type) pairs
      Returns:
      canonical struct type descriptor

    • createArrayType

      RelDataType createArrayType(RelDataType elementType, long maxCardinality)
      Creates an array type. Arrays are ordered collections of elements.
      Parameters:
      elementType - type of the elements of the array
      maxCardinality - maximum array size, or -1 for unlimited
      Returns:
      canonical array type descriptor

    • createMapType

      RelDataType createMapType(RelDataType keyType, RelDataType valueType)
      Creates a map type. Maps are unordered collections of key/value pairs.
      Parameters:
      keyType - type of the keys of the map
      valueType - type of the values of the map
      Returns:
      canonical map type descriptor

    • createMeasureType

      RelDataType createMeasureType(RelDataType valueType)
      Creates a measure type.
      Parameters:
      valueType - type of the values of the measure
      Returns:
      canonical measure type descriptor

    • createMultisetType

      RelDataType createMultisetType(RelDataType elementType, long maxCardinality)
      Creates a multiset type. Multisets are unordered collections of elements.
      Parameters:
      elementType - type of the elements of the multiset
      maxCardinality - maximum collection size, or -1 for unlimited
      Returns:
      canonical multiset type descriptor

    • copyType

      RelDataType copyType(RelDataType type)
      Duplicates a type, making a deep copy. Normally, this is a no-op, since canonical type objects are returned. However, it is useful when copying a type from one factory to another.
      Parameters:
      type - input type
      Returns:
      output type, a new object equivalent to input type

    • createTypeWithNullability

      RelDataType createTypeWithNullability(RelDataType type, boolean nullable)
      Creates a type that is the same as another type but with possibly different nullability. The output type may be identical to the input type. For type systems without a concept of nullability, the return value is always the same as the input.
      Parameters:
      type - input type
      nullable - true to request a nullable type; false to request a NOT NULL type
      Returns:
      output type, same as input type except with specified nullability
      Throws:
      NullPointerException - if type is null

    • createTypeWithCharsetAndCollation

      RelDataType createTypeWithCharsetAndCollation(RelDataType type, Charset charset, SqlCollation collation)
      Creates a type that is the same as another type but with possibly different charset or collation. For types without a concept of charset or collation this function must throw an error.
      Parameters:
      type - input type
      charset - charset to assign
      collation - collation to assign
      Returns:
      output type, same as input type except with specified charset and collation

    • getDefaultCharset

      Charset getDefaultCharset()
      Returns the default Charset (valid if this is a string type).

    • leastRestrictive

      default @Nullable RelDataType leastRestrictive(List<RelDataType> types)
      Returns the most general of a set of types using the default type mapping rule.
      Parameters:
      types - input types to be combined using union (not null, not empty)
      Returns:
      canonical union type descriptor
      See Also:

    • leastRestrictive

      @Nullable RelDataType leastRestrictive(List<RelDataType> types, SqlTypeMappingRule mappingRule)
      Returns the most general of a set of types (that is, one type to which they can all be cast), or null if conversion is not possible. The result may be a new type that is less restrictive than any of the input types, e.g. leastRestrictive(INT, NUMERIC(3, 2)) could be NUMERIC(12, 2).

      Accepts a SqlTypeMappingRule that can be used to change casting behavior.

      Parameters:
      types - input types to be combined using union (not null, not empty)
      mappingRule - rule that determines whether types are convertible
      Returns:
      canonical union type descriptor

    • createSqlType

      RelDataType createSqlType(SqlTypeName typeName)
      Creates a SQL type with no precision or scale.
      Parameters:
      typeName - Name of the type, for example SqlTypeName.BOOLEAN, never null
      Returns:
      canonical type descriptor

    • createUnknownType

      RelDataType createUnknownType()
      Creates a SQL type that represents the "unknown" type. It is only equal to itself, and is distinct from the NULL type.
      Returns:
      unknown type

    • createSqlType

      RelDataType createSqlType(SqlTypeName typeName, int precision)
      Creates a SQL type with length (precision) but no scale.
      Parameters:
      typeName - Name of the type, for example SqlTypeName.VARCHAR. Never null.
      precision - Maximum length of the value (non-numeric types) or the precision of the value (numeric/datetime types). Must be non-negative or RelDataType.PRECISION_NOT_SPECIFIED.
      Returns:
      canonical type descriptor

    • createSqlType

      RelDataType createSqlType(SqlTypeName typeName, int precision, int scale)
      Creates a SQL type with precision and scale.
      Parameters:
      typeName - Name of the type, for example SqlTypeName.DECIMAL. Never null.
      precision - Precision of the value. Must be non-negative or RelDataType.PRECISION_NOT_SPECIFIED.
      scale - scale of the values, i.e. the number of decimal places to shift the value. For example, a NUMBER(10,3) value of "123.45" is represented "123450" (that is, multiplied by 10^3). A negative scale is valid.
      Returns:
      canonical type descriptor

    • createSqlIntervalType

      RelDataType createSqlIntervalType(SqlIntervalQualifier intervalQualifier)
      Creates a SQL interval type.
      Parameters:
      intervalQualifier - contains information if it is a year-month or a day-time interval along with precision information
      Returns:
      canonical type descriptor

    • createDecimalProduct

      @Deprecated @Nullable RelDataType createDecimalProduct(RelDataType type1, RelDataType type2)
      Deprecated.
      Use RelDataTypeSystem.deriveDecimalMultiplyType(RelDataTypeFactory, RelDataType, RelDataType)
      Infers the return type of a decimal multiplication. Decimal multiplication involves at least one decimal operand and requires both operands to have exact numeric types.
      Parameters:
      type1 - type of the first operand
      type2 - type of the second operand
      Returns:
      the result type for a decimal multiplication, or null if decimal multiplication should not be applied to the operands.

    • useDoubleMultiplication

      @Deprecated boolean useDoubleMultiplication(RelDataType type1, RelDataType type2)
      Deprecated.
      Use RelDataTypeSystem.shouldUseDoubleMultiplication(RelDataTypeFactory, RelDataType, RelDataType)
      Returns whether a decimal multiplication should be implemented by casting arguments to double values.

      Pre-condition: createDecimalProduct(type1, type2) != null

    • createDecimalQuotient

      @Deprecated @Nullable RelDataType createDecimalQuotient(RelDataType type1, RelDataType type2)
      Deprecated.
      Use RelDataTypeSystem.deriveDecimalDivideType(RelDataTypeFactory, RelDataType, RelDataType)
      Infers the return type of a decimal division. Decimal division involves at least one decimal operand and requires both operands to have exact numeric types.
      Parameters:
      type1 - type of the first operand
      type2 - type of the second operand
      Returns:
      the result type for a decimal division, or null if decimal division should not be applied to the operands.

    • decimalOf

      RelDataType decimalOf(RelDataType type)
      Create a decimal type equivalent to the numeric type, this is related to specific system implementation, you can override this logic if it is required.
      Parameters:
      type - the numeric type to create decimal type with
      Returns:
      decimal equivalence of the numeric type.

    • builder

      RelDataTypeFactory.FieldInfoBuilder builder()
      Creates a RelDataTypeFactory.FieldInfoBuilder. But since FieldInfoBuilder is deprecated, we recommend that you use its base class RelDataTypeFactory.Builder, which is not deprecated.