org.apache.calcite.adapter.clone

Enum ArrayTable.RepresentationType

java.lang.Object

java.lang.Enum<ArrayTable.RepresentationType>

org.apache.calcite.adapter.clone.ArrayTable.RepresentationType

All Implemented Interfaces:

Serializable, Comparable<ArrayTable.RepresentationType>

Enclosing class:

ArrayTable

static enum ArrayTable.RepresentationType
extends Enum<ArrayTable.RepresentationType>

How a column's values are represented.

Enum Constant Summary

Enum Constants

Enum Constant and Description
BIT_SLICED_PRIMITIVE_ARRAY Bit-sliced primitive array.
BYTE_STRING_DICTIONARY Compressed byte array table.
CONSTANT Constant.
OBJECT_ARRAY Object array.
OBJECT_DICTIONARY Dictionary of objects.
PRIMITIVE_ARRAY Array of primitives.
PRIMITIVE_DICTIONARY Dictionary of primitives.
STRING_DICTIONARY Compressed string table.

Method Summary

Modifier and Type	Method and Description
static ArrayTable.RepresentationType	valueOf(String name) Returns the enum constant of this type with the specified name.
static ArrayTable.RepresentationType[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

CONSTANT

public static final ArrayTable.RepresentationType CONSTANT

Constant. Contains only one value.

We can't store 0-bit values in an array: we'd have no way of knowing how many there were.

See Also:

ArrayTable.Constant

OBJECT_ARRAY

public static final ArrayTable.RepresentationType OBJECT_ARRAY

Object array. Null values are represented by null. Values may or may not be canonized; if canonized, = and != can be implemented using pointer.

See Also:

ArrayTable.ObjectArray

PRIMITIVE_ARRAY

public static final ArrayTable.RepresentationType PRIMITIVE_ARRAY

Array of primitives. Null values not possible. Only for primitive types (and not optimal for boolean).

See Also:

ArrayTable.PrimitiveArray

BIT_SLICED_PRIMITIVE_ARRAY

public static final ArrayTable.RepresentationType BIT_SLICED_PRIMITIVE_ARRAY

Bit-sliced primitive array. Values are bitCount bits each, and interpreted as signed. Stored as an array of long values.

If gcd(bitCount, 64) != 0, some values will cross boundaries. bits each. But for all of those values except 4, there is a primitive type (8 byte, 16 short, 32 int) which is more efficient.

See Also:

ArrayTable.BitSlicedPrimitiveArray

PRIMITIVE_DICTIONARY

public static final ArrayTable.RepresentationType PRIMITIVE_DICTIONARY

Dictionary of primitives. Use one of the previous methods to store unsigned offsets into the dictionary. Dictionary is canonized and sorted, so v1 < v2 if and only if code(v1) < code(v2). The dictionary may or may not contain a null value.

The dictionary is not beneficial unless the codes are significantly shorter than the values. A column of long values with many duplicates is a win; a column of mostly distinct short values is likely a loss. The other win is if there are null values; otherwise the best option would be an OBJECT_ARRAY.

See Also:

ArrayTable.PrimitiveDictionary

OBJECT_DICTIONARY

public static final ArrayTable.RepresentationType OBJECT_DICTIONARY

Dictionary of objects. Use one of the previous methods to store unsigned offsets into the dictionary.

See Also:

ArrayTable.ObjectDictionary

STRING_DICTIONARY

public static final ArrayTable.RepresentationType STRING_DICTIONARY

Compressed string table. Block of char data. Strings represented using an unsigned offset into the table (stored using one of the previous methods).

First 2 bytes are unsigned length; subsequent bytes are string contents. The null value, strings longer than 64k and strings that occur very commonly are held in an 'exceptions' array and are recognized by their high offsets. Other strings are created on demand (this reduces the number of objects that need to be created during deserialization from cache.

See Also:

ArrayTable.StringDictionary

BYTE_STRING_DICTIONARY

public static final ArrayTable.RepresentationType BYTE_STRING_DICTIONARY

Compressed byte array table. Similar to compressed string table.

See Also:

ArrayTable.ByteStringDictionary

Method Detail

values

public static ArrayTable.RepresentationType[] 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 (ArrayTable.RepresentationType c : ArrayTable.RepresentationType.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static ArrayTable.RepresentationType 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