org.apache.flink.types

Interface NormalizableKey<T>

All Superinterfaces:

Comparable<T>, IOReadableWritable, Key<T>, Serializable, Value

All Known Implementing Classes:

BooleanValue, ByteValue, CharValue, IntValue, LongValue, NullValue, ShortValue, StringValue

public interface NormalizableKey<T>
extends Key<T>

The base interface for normalizable keys. Normalizable keys can create a binary representation of themselves that is byte-wise comparable. The byte-wise comparison of two normalized keys proceeds until all bytes are compared or two bytes at the corresponding positions are not equal. If two corresponding byte values are not equal, the lower byte value indicates the lower key. If both normalized keys are byte-wise identical, the actual key may have to be looked at to determine which one is actually lower.

The latter depends on whether the normalized key covers the entire key or is just a prefix of the key. A normalized key is considered a prefix, if its length is less than the maximal normalized key length.

Method Summary

Methods

Modifier and Type	Method and Description
void	copyNormalizedKey(MemorySegment memory, int offset, int len) Writes a normalized key for the given record into the target byte array, starting at the specified position an writing exactly the given number of bytes.
int	getMaxNormalizedKeyLen() Gets the maximal length of normalized keys that the data type would produce to determine the order of instances solely by the normalized key.

Methods inherited from interface org.apache.flink.types.Key

equals, hashCode

Methods inherited from interface org.apache.flink.core.io.IOReadableWritable

read, write

Methods inherited from interface java.lang.Comparable

compareTo

Method Detail

getMaxNormalizedKeyLen

int getMaxNormalizedKeyLen()

Gets the maximal length of normalized keys that the data type would produce to determine the order of instances solely by the normalized key. A value of Integer.MAX_VALUE is interpreted as infinite.

For example, 32 bit integers return four, while Strings (potentially unlimited in length) return Integer.MAX_VALUE.

Returns:

The maximal length of normalized keys.

copyNormalizedKey

void copyNormalizedKey(MemorySegment memory,
                     int offset,
                     int len)

Writes a normalized key for the given record into the target byte array, starting at the specified position an writing exactly the given number of bytes. Note that the comparison of the bytes is treating the bytes as unsigned bytes: int byteI = bytes[i] & 0xFF;

If the meaningful part of the normalized key takes less than the given number of bytes, than it must be padded. Padding is typically required for variable length data types, such as strings. The padding uses a special character, either 0 or 0xff, depending on whether shorter values are sorted to the beginning or the end.

Parameters:

memory - The memory segment to put the normalized key bytes into.

offset - The offset in the byte array where the normalized key's bytes should start.

len - The number of bytes to put.