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.
default Token	getMaximumToken() The biggest token for this partitioner, unlike getMinimumToken, this token is actually used and users wanting to include all tokens need to do getMaximumToken().maxKeyBound() Not implemented for the ordered partitioners
Token	getMinimumToken()
Token	getRandomToken()
Token	getRandomToken(java.util.Random random)
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()
Token	split(Token left, Token right, double ratioToLeft) Calculate a Token which take approximate 0 <= ratioToLeft <= 1 ownership of the given range.
default java.util.Optional<Splitter>	splitter()

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.

split

Token split(Token left,
            Token right,
            double ratioToLeft)

Calculate a Token which take approximate 0 <= ratioToLeft <= 1 ownership of the given range.

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.)

getMaximumToken

default Token getMaximumToken()

The biggest token for this partitioner, unlike getMinimumToken, this token is actually used and users wanting to include all tokens need to do getMaximumToken().maxKeyBound() Not implemented for the ordered partitioners

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

getRandomToken

Token getRandomToken(java.util.Random random)

Parameters:

random - instance of Random to use when generating the token

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.

splitter

default java.util.Optional<Splitter> splitter()