org.apache.cassandra.db

Interface ClusteringPrefix

All Superinterfaces:

Clusterable, IMeasurableMemory

All Known Implementing Classes:

AbstractClusteringPrefix, Clustering, RangeTombstone.Bound, Slice.Bound

public interface ClusteringPrefix
extends IMeasurableMemory, Clusterable

A clustering prefix is the unit of what a ClusteringComparator can compare.

It holds values for the clustering columns of a table (potentially only a prefix of all of them) and has a "kind" that allows us to implement slices with inclusive and exclusive bounds.

In practice, ClusteringPrefix is just the common parts to its 3 main subtype: Clustering and Slice.Bound/RangeTombstone.Bound, where: 1) Clustering represents the clustering values for a row, i.e. the values for it's clustering columns. 2) Slice.Bound represents a bound (start or end) of a slice (of rows). 3) RangeTombstoneBoundMarker.Bound represents a range tombstone marker "bound". See those classes for more details.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ClusteringPrefix.Deserializer Helper class that makes the deserialization of clustering prefixes faster.
static class	ClusteringPrefix.Kind The kind of clustering prefix this actually is.
static class	ClusteringPrefix.Serializer

Field Summary

Fields

Modifier and Type	Field and Description
static ClusteringPrefix.Serializer	serializer

Method Summary

Modifier and Type	Method and Description
int	dataSize() The size of the data hold by this prefix.
void	digest(java.security.MessageDigest digest) Adds the data of this clustering prefix to the provided digest.
java.nio.ByteBuffer	get(int i) Retrieves the ith value of this prefix.
java.nio.ByteBuffer[]	getRawValues() The values of this prefix as an array.
ClusteringPrefix.Kind	kind()
int	size() The number of values in this prefix.
java.lang.String	toString(CFMetaData metadata) Generates a proper string representation of the prefix.

Methods inherited from interface org.apache.cassandra.cache.IMeasurableMemory

unsharedHeapSize

Methods inherited from interface org.apache.cassandra.db.Clusterable

clustering

Field Detail

serializer

static final ClusteringPrefix.Serializer serializer

Method Detail

kind

ClusteringPrefix.Kind kind()

size

int size()

The number of values in this prefix. There can't be more values that the this is a prefix of has of clustering columns.

Returns:

the number of values in this prefix.

get

java.nio.ByteBuffer get(int i)

Retrieves the ith value of this prefix.

Parameters:

i - the index of the value to retrieve. Must be such that 0 <= i < size().

Returns:

the ith value of this prefix. Note that a value can be null.

digest

void digest(java.security.MessageDigest digest)

Adds the data of this clustering prefix to the provided digest.

Parameters:

digest - the digest to which to add this prefix.

dataSize

int dataSize()

The size of the data hold by this prefix.

Returns:

the size of the data hold by this prefix (this is not the size of the object in memory, just the size of the data it stores).

toString

java.lang.String toString(CFMetaData metadata)

Generates a proper string representation of the prefix.

Parameters:

metadata - the metadata for the table the clustering prefix is of.

Returns:

a human-readable string representation fo this prefix.

getRawValues

java.nio.ByteBuffer[] getRawValues()

The values of this prefix as an array.

Please note that this may or may not require an array creation. So 1) you should *not* modify the returned array and 2) it's more efficient to use size() and get(int) unless you actually need an array.

Returns:

the values for this prefix as an array.