Package org.apache.druid.segment.column

Enum ValueType

  • All Implemented Interfaces:
    Serializable, Comparable<ValueType>, TypeDescriptor
    public enum ValueType
extends Enum<ValueType>
implements TypeDescriptor
    This enumeration defines the high level classification of the Druid type system, used by ColumnType to indicate the type of data stored in columns and produced by expressions and aggregations, used to allow query processing engine algorithms to compute results, used to compute query result row signatures, and all other type needs. Currently, only the primitive types (isPrimitive() is true) and COMPLEX can be stored in columns and are also the only types handled directly by the query engines. Array types can currently be produced by expressions and by some post-aggregators, but do not currently have special engine handling, and should be used by implementors sparingly until full engine support is in place. Aggregators should never specify array types as their output type until the engines fully support these types.
    See Also:
    ColumnType, TypeSignature

    • Enum Constant Detail

      • DOUBLE

        public static final ValueType DOUBLE
        64-bit double precision floating point number primitive type. This type may be used as a grouping key, or as an input to any aggregators which support primitive numerical operations like sums, minimums, maximums, etc, as well as an input to expression virtual columns.

      • FLOAT

        public static final ValueType FLOAT
        32-bit single precision floating point number primitive type. This type may be used as a grouping key, or as an input to any aggregators which support primitive numerical operations like sums, minimums, maximums, etc, as well as an input to expression virtual columns.

      • LONG

        public static final ValueType LONG
        64-bit integer number primitve type. This type may be used as a grouping key, or as an input to any aggregators which support primitive numerical operations like sums, minimums, maximums, etc, as well as an input to expression virtual columns.

      • STRING

        public static final ValueType STRING
        String object type. This type may be used as a grouping key, an input to certain types of complex sketch aggregators, and as an input to expression virtual columns. String types might potentially be 'multi-valued' when stored in segments, and contextually at various layers of query processing, but this information is not available at this level. Strings are typically represented as String. Multi-value strings appear as List when necessary to represent multiple values, and can vary between string and list from one row to the next.

      • COMPLEX

        public static final ValueType COMPLEX
        Placeholder for arbitrary 'complex' types, which have a corresponding serializer/deserializer implementation. Note that knowing a type is complex alone isn't enough information to work with it directly, and additional information in the form of a type name which must be registered in the complex type registry. Complex types are not currently supported as a grouping key for aggregations. Complex types can be used as inputs to aggregators, in cases where the specific aggregator supports the specific complex type. Filtering on these types with standard filters is not well supported, and will be treated as null values. These types are represented by the individual Java type associated with the complex type name as defined in the type registry.

      • ARRAY

        public static final ValueType ARRAY
        Placeholder for arbitrary arrays of other ValueType. This type has limited support as a grouping key for aggregations, ARRAY of STRING, LONG, DOUBLE, and FLOAT are supported, but ARRAY types in general are not. ARRAY types cannot be used as an input for numerical primitive aggregations such as sums, and have limited support as an input among complex type sketch aggregators. There are currently no native ARRAY typed columns, but they may be produced by expression virtual columns, aggregators, and post-aggregators. Arrays are represented as Object[], long[], double[], or float[]. The preferred type is Object[], since the expression system is the main consumer of arrays, and the expression system uses Object[] internally. Some code represents arrays in other ways; in particular the groupBy engine and SQL result layer. Over time we expect these usages to migrate to Object[], long[], double[], and float[].

    • Method Detail

      • values

        public static ValueType[] values()
        Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows: 
        for (ValueType c : ValueType.values())
    System.out.println(c);
        Returns:
        an array containing the constants of this enum type, in the order they are declared

      • valueOf

        public static ValueType valueOf​(String name)
        Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
        Parameters:
        name - the name of the enum constant to be returned.
        Returns:
        the enum constant with the specified name
        Throws:
        IllegalArgumentException - if this enum type has no constant with the specified name
        NullPointerException - if the argument is null

      • isNumeric

        public static boolean isNumeric​(ValueType type)

      • isArray

        public static boolean isArray​(ValueType type)