org.apache.calcite.rel.type

Interface RelDataType

All Known Implementing Classes:

AbstractSqlType, ArraySqlType, BasicSqlType, IntervalSqlType, JavaRecordType, MapSqlType, MultisetSqlType, ObjectSqlType, RelCrossType, RelDataTypeFactoryImpl.JavaType, RelDataTypeImpl, RelRecordType

public interface RelDataType

RelDataType represents the type of a scalar expression or entire row returned from a relational expression.

This is a somewhat "fat" interface which unions the attributes of many different type classes into one. Inelegant, but since our type system was defined before the advent of Java generics, it avoids a lot of typecasting.

Field Summary

Fields

Modifier and Type	Field and Description
static int	PRECISION_NOT_SPECIFIED
static int	SCALE_NOT_SPECIFIED

Method Summary

Methods

Modifier and Type	Method and Description
Charset	getCharset() Gets this type's character set, or null if this type cannot carry a character set or has no character set defined.
SqlCollation	getCollation() Gets this type's collation, or null if this type cannot carry a collation or has no collation defined.
RelDataTypeComparability	getComparability()
RelDataType	getComponentType() Gets the component type if this type is a collection, otherwise null.
RelDataTypeFamily	getFamily() Gets a canonical object representing the family of this type.
RelDataTypeField	getField(String fieldName, boolean caseSensitive, boolean elideRecord) Looks up a field by name.
int	getFieldCount() Returns the number of fields in a struct type.
List<RelDataTypeField>	getFieldList() Gets the fields in a struct type.
List<String>	getFieldNames() Returns the names of the fields in a struct type.
String	getFullTypeString() Gets a string representation of this type with full detail such as character set and nullability.
SqlIntervalQualifier	getIntervalQualifier() Gets this type's interval qualifier, or null if this is not an interval type.
RelDataType	getKeyType() Gets the key type if this type is a map, otherwise null.
RelDataTypePrecedenceList	getPrecedenceList()
int	getPrecision() Gets the JDBC-defined precision for values of this type.
int	getScale() Gets the scale of this type.
SqlIdentifier	getSqlIdentifier() Gets the SqlIdentifier associated with this type.
SqlTypeName	getSqlTypeName() Gets the SqlTypeName of this type.
RelDataType	getValueType() Gets the value type if this type is a map, otherwise null.
boolean	isNullable() Queries whether this type allows null values.
boolean	isStruct() Queries whether this is a structured type.
String	toString() Gets a string representation of this type without detail such as character set and nullability.

Field Detail

SCALE_NOT_SPECIFIED

static final int SCALE_NOT_SPECIFIED

See Also:

Constant Field Values

PRECISION_NOT_SPECIFIED

static final int PRECISION_NOT_SPECIFIED

See Also:

Constant Field Values

Method Detail

isStruct

boolean isStruct()

Queries whether this is a structured type.

Returns:

whether this type has fields; examples include rows and user-defined structured types in SQL, and classes in Java

getFieldList

List<RelDataTypeField> getFieldList()

Gets the fields in a struct type. The field count is equal to the size of the returned list.

Returns:

read-only list of fields

getFieldNames

List<String> getFieldNames()

Returns the names of the fields in a struct type. The field count is equal to the size of the returned list.

Returns:

read-only list of field names

getFieldCount

int getFieldCount()

Returns the number of fields in a struct type.

This method is equivalent to getFieldList() ().size().

getField

RelDataTypeField getField(String fieldName,
                        boolean caseSensitive,
                        boolean elideRecord)

Looks up a field by name.

NOTE: Be careful choosing the value of caseSensitive:

• If the field name was supplied by an end-user (e.g. as a column alias in SQL), use your session's case-sensitivity setting.
• Only hard-code true if you are sure that the field name is internally generated.
• Hard-coding false is almost certainly wrong.

Parameters:

fieldName - Name of field to find

caseSensitive - Whether match is case-sensitive

elideRecord - Whether to find fields nested within records

Returns:

named field, or null if not found

isNullable

boolean isNullable()

Queries whether this type allows null values.

Returns:

whether type allows null values

getComponentType

RelDataType getComponentType()

Gets the component type if this type is a collection, otherwise null.

Returns:

canonical type descriptor for components

getKeyType

RelDataType getKeyType()

Gets the key type if this type is a map, otherwise null.

Returns:

canonical type descriptor for key

getValueType

RelDataType getValueType()

Gets the value type if this type is a map, otherwise null.

Returns:

canonical type descriptor for value

getCharset

Charset getCharset()

Gets this type's character set, or null if this type cannot carry a character set or has no character set defined.

Returns:

charset of type

getCollation

SqlCollation getCollation()

Gets this type's collation, or null if this type cannot carry a collation or has no collation defined.

Returns:

collation of type

getIntervalQualifier

SqlIntervalQualifier getIntervalQualifier()

Gets this type's interval qualifier, or null if this is not an interval type.

Returns:

interval qualifier

getPrecision

int getPrecision()

Gets the JDBC-defined precision for values of this type. Note that this is not always the same as the user-specified precision. For example, the type INTEGER has no user-specified precision, but this method returns 10 for an INTEGER type.

Returns PRECISION_NOT_SPECIFIED (-1) if precision is not applicable for this type.

Returns:

number of decimal digits for exact numeric types; number of decimal digits in mantissa for approximate numeric types; number of decimal digits for fractional seconds of datetime types; length in characters for character types; length in bytes for binary types; length in bits for bit types; 1 for BOOLEAN; -1 if precision is not valid for this type

getScale

int getScale()

Gets the scale of this type. Returns SCALE_NOT_SPECIFIED (-1) if scale is not valid for this type.

Returns:

number of digits of scale

getSqlTypeName

SqlTypeName getSqlTypeName()

Gets the SqlTypeName of this type.

Returns:

SqlTypeName, or null if this is not an SQL predefined type

getSqlIdentifier

SqlIdentifier getSqlIdentifier()

Gets the SqlIdentifier associated with this type. For a predefined type, this is a simple identifier based on getSqlTypeName(). For a user-defined type, this is a compound identifier which uniquely names the type.

Returns:

SqlIdentifier, or null if this is not an SQL type

toString

String toString()

Gets a string representation of this type without detail such as character set and nullability.

Overrides:

toString in class Object

Returns:

abbreviated type string

getFullTypeString

String getFullTypeString()

Gets a string representation of this type with full detail such as character set and nullability. The string must serve as a "digest" for this type, meaning two types can be considered identical iff their digests are equal.

Returns:

full type string

getFamily

RelDataTypeFamily getFamily()

Gets a canonical object representing the family of this type. Two values can be compared if and only if their types are in the same family.

Returns:

canonical object representing type family

getPrecedenceList

RelDataTypePrecedenceList getPrecedenceList()

Returns:

precedence list for this type

getComparability

RelDataTypeComparability getComparability()

Returns:

the category of comparison operators which make sense when applied to values of this type