org.apache.cassandra.dht

Interface IPartitioner

All Known Implementing Classes:

ByteOrderedPartitioner, LocalPartitioner, Murmur3Partitioner, OrderPreservingPartitioner, RandomPartitioner

public interface IPartitioner

Method Summary

Modifier and Type	Method and Description
DecoratedKey	decorateKey(java.nio.ByteBuffer key) Transform key to object representation of the on-disk format.
java.util.Map<Token,java.lang.Float>	describeOwnership(java.util.List<Token> sortedTokens) Calculate the deltas between tokens in the ring in order to compare relative sizes.
Token	getMinimumToken()
Token	getRandomToken()
Token	getToken(java.nio.ByteBuffer key)
Token.TokenFactory	getTokenFactory()
AbstractType<?>	getTokenValidator()
Token	midpoint(Token left, Token right) Calculate a Token representing the approximate "middle" of the given range.
AbstractType<?>	partitionOrdering() Abstract type that orders the same way as DecoratedKeys provided by this partitioner.
boolean	preservesOrder()

Method Detail

decorateKey

DecoratedKey decorateKey(java.nio.ByteBuffer key)

Transform key to object representation of the on-disk format.

Parameters:

key - the raw, client-facing key

Returns:

decorated version of key

midpoint

Token midpoint(Token left,
               Token right)

Calculate a Token representing the approximate "middle" of the given range.

Returns:

The approximate midpoint between left and right.

getMinimumToken

Token getMinimumToken()

Returns:

A Token smaller than all others in the range that is being partitioned. Not legal to assign to a node or key. (But legal to use in range scans.)

getToken

Token getToken(java.nio.ByteBuffer key)

Returns:

a Token that can be used to route a given key (This is NOT a method to create a Token from its string representation; for that, use TokenFactory.fromString.)

getRandomToken

Token getRandomToken()

Returns:

a randomly generated token

getTokenFactory

Token.TokenFactory getTokenFactory()

preservesOrder

boolean preservesOrder()

Returns:

True if the implementing class preserves key order in the Tokens it generates.

describeOwnership

java.util.Map<Token,java.lang.Float> describeOwnership(java.util.List<Token> sortedTokens)

Calculate the deltas between tokens in the ring in order to compare relative sizes.

Parameters:

sortedTokens - a sorted List of Tokens

Returns:

the mapping from 'token' to 'percentage of the ring owned by that token'.

getTokenValidator

AbstractType<?> getTokenValidator()

partitionOrdering

AbstractType<?> partitionOrdering()

Abstract type that orders the same way as DecoratedKeys provided by this partitioner. Used by secondary indices.