Package org.apache.druid.segment.column

Class ColumnType

java.lang.Object

org.apache.druid.segment.column.BaseTypeSignature<ValueType>

org.apache.druid.segment.column.ColumnType

All Implemented Interfaces:

Cacheable, TypeSignature<ValueType>

public class ColumnType
extends BaseTypeSignature<ValueType>
implements Cacheable

Native Druid types.

See Also:

• TypeSignature

Field Summary

Fields

Modifier and Type	Field	Description
static final ColumnType	DOUBLE	Druid 64-bit double precision floating point number primitive type.
static final ColumnType	DOUBLE_ARRAY	An array of Doubles.
static final ColumnType	FLOAT	Druid 32-bit single precision floating point number primitive type.
static final ColumnType	FLOAT_ARRAY	An array of Floats.
static final ColumnType	LONG	Druid 64-bit integer number primitive type.
static final ColumnType	LONG_ARRAY	An array of Longs.
static final ColumnType	NESTED_DATA
static final ColumnType	STRING	Druid string type.
static final ColumnType	STRING_ARRAY	An array of Strings.
static final ColumnType	UNKNOWN_COMPLEX	Placeholder type for an "unknown" complex, which is used when the complex type name was "lost" or unavailable for whatever reason, to indicate an opaque type that cannot be generically handled with normal complex type handling mechanisms.

Fields inherited from class org.apache.druid.segment.column.BaseTypeSignature

complexTypeName, elementType, type

Constructor Summary

Constructors

Constructor	Description
ColumnType(ValueType type, String complexTypeName, ColumnType elementType)

Method Summary

Modifier and Type	Method	Description
static ColumnType	fromCapabilities(ColumnCapabilities capabilities)
static ColumnType	fromString(String typeName)
byte[]	getCacheKey()	Get a byte array used as a cache key.
static ColumnType	leastRestrictiveType(Iterable<ColumnType> types)
static ColumnType	leastRestrictiveType(ColumnType type, ColumnType other)	Finds the type that can best represent both types, or none if there is no type information.
static ColumnType	ofArray(ColumnType elementType)
static ColumnType	ofComplex(String complexTypeName)

Methods inherited from class org.apache.druid.segment.column.BaseTypeSignature

equals, getComplexTypeName, getElementType, getNullableStrategy, getStrategy, getType, hashCode, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.druid.segment.column.TypeSignature

anyOf, asTypeString, is, isArray, isNumeric, isPrimitive, isPrimitiveArray

Field Details

STRING

public static final ColumnType STRING

Druid string type. Values will be represented as String or List<String> in the case of multi-value string columns. ColumnType has insufficient information to distinguish between single and multi-value strings, this requires a specific TypeSignature implementation which is supplied by segments, 'ColumnCapabilities', which is available at a higher layer and provides the method 'hasMultipleValues'.

See Also:

• ValueType.STRING

LONG

public static final ColumnType LONG

Druid 64-bit integer number primitive type. Values will be represented as Java long or Long.

See Also:

• ValueType.LONG

DOUBLE

public static final ColumnType DOUBLE

Druid 64-bit double precision floating point number primitive type. Values will be represented as Java double or Double.

See Also:

• ValueType.DOUBLE

FLOAT

public static final ColumnType FLOAT

Druid 32-bit single precision floating point number primitive type. Values will be represented as Java float or Float.

See Also:

• ValueType.FLOAT

STRING_ARRAY

public static final ColumnType STRING_ARRAY

An array of Strings. Values will be represented as Object[]

See Also:

• ValueType.ARRAY
• ValueType.STRING

LONG_ARRAY

public static final ColumnType LONG_ARRAY

An array of Longs. Values will be represented as Object[] or long[]

See Also:

• ValueType.ARRAY
• ValueType.LONG

DOUBLE_ARRAY

public static final ColumnType DOUBLE_ARRAY

An array of Doubles. Values will be represented as Object[] or double[].

See Also:

• ValueType.ARRAY
• ValueType.DOUBLE

FLOAT_ARRAY

public static final ColumnType FLOAT_ARRAY

An array of Floats. Values will be represented as Object[] or float[].

See Also:

• ValueType.ARRAY
• ValueType.FLOAT

NESTED_DATA

public static final ColumnType NESTED_DATA

UNKNOWN_COMPLEX

public static final ColumnType UNKNOWN_COMPLEX

Placeholder type for an "unknown" complex, which is used when the complex type name was "lost" or unavailable for whatever reason, to indicate an opaque type that cannot be generically handled with normal complex type handling mechanisms. Prefer to use a ColumnType with the BaseTypeSignature.complexTypeName set for most complex type matters if at all possible.

See Also:

• ValueType.COMPLEX

Constructor Details

ColumnType

public ColumnType(ValueType type,
 @Nullable
 String complexTypeName,
 @Nullable
 ColumnType elementType)

Method Details

fromString

@Nullable
public static ColumnType fromString(@Nullable
 String typeName)

fromCapabilities

@Nullable
public static ColumnType fromCapabilities(@Nullable
 ColumnCapabilities capabilities)

ofArray

public static ColumnType ofArray(ColumnType elementType)

ofComplex

public static ColumnType ofComplex(@Nullable
 String complexTypeName)

leastRestrictiveType

@Nullable
public static ColumnType leastRestrictiveType(@Nullable
 ColumnType type,
 @Nullable
 ColumnType other)
                                       throws Types.IncompatibleTypeException

Finds the type that can best represent both types, or none if there is no type information. If either type is null, the other type is returned. If both types are null, this method returns null as we cannot determine any useful type information. If the types are ValueType.COMPLEX, they must be the same complex type, else this function throws a IllegalArgumentException as the types are truly incompatible, with the exception of NESTED_DATA which is complex and represents nested AND mixed type data so is instead treated as the 'least restrictive type' if present. If both types are ValueType.ARRAY, the result is an array of the result of calling this method again on BaseTypeSignature.elementType. If only one type is an array, the result is an array type of calling this method on the non-array type and the array element type. After arrays, if either type is ValueType.STRING, the result is ValueType.STRING. If both types are numeric, then the result will be ValueType.LONG if both are longs, ValueType.FLOAT if both are floats, else ValueType.DOUBLE.

Throws:

Types.IncompatibleTypeException

See Also:

• for a similar method used for expression type inference

leastRestrictiveType

@Nullable
public static ColumnType leastRestrictiveType(Iterable<ColumnType> types)

getCacheKey

public byte[] getCacheKey()

Description copied from interface: Cacheable

Get a byte array used as a cache key.

Specified by:

getCacheKey in interface Cacheable

Returns:

bytes to be used as cache key - or null if this object should not be cached.