org.apache.cassandra.db

Interface ClusteringPrefix<V>

All Superinterfaces:

Clusterable<V>, IMeasurableMemory

All Known Subinterfaces:

Clustering<V>, ClusteringBound<V>, ClusteringBoundary<V>, ClusteringBoundOrBoundary<V>

All Known Implementing Classes:

AbstractArrayClusteringPrefix, AbstractBufferClusteringPrefix, AbstractOnHeapClusteringPrefix, ArrayClustering, ArrayClusteringBound, ArrayClusteringBoundary, ArrayClusteringBoundOrBoundary, BufferClustering, BufferClusteringBound, BufferClusteringBoundary, BufferClusteringBoundOrBoundary, NativeClustering

public interface ClusteringPrefix<V>
extends IMeasurableMemory, Clusterable<V>

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 ClusteringBound/ClusteringBoundary, where: 1) Clustering represents the clustering values for a row, i.e. the values for it's clustering columns. 2) ClusteringBound represents a bound (start or end) of a slice (of rows) or a range tombstone. 3) ClusteringBoundary represents the threshold between two adjacent range tombstones. 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
ValueAccessor<V>	accessor()
default java.nio.ByteBuffer	bufferAt(int i)
default int	dataSize() The size of the data hold by this prefix.
default void	digest(Digest digest) Adds the data of this clustering prefix to the provided Digest instance.
static boolean	equals(ClusteringPrefix<?> prefix, java.lang.Object o)
static <V1,V2> boolean	equals(ClusteringPrefix<V1> left, ClusteringPrefix<V2> right)
V	get(int i) Retrieves the ith value of this prefix.
java.nio.ByteBuffer[]	getBufferArray()
V[]	getRawValues() The values of this prefix as an array.
static <V> int	hashCode(ClusteringPrefix<V> prefix)
default boolean	isBottom()
default boolean	isEmpty()
default boolean	isTop()
ClusteringPrefix.Kind	kind()
ClusteringPrefix<V>	minimize() If the prefix contains byte buffers that can be minimized (see ByteBufferUtil.minimalBufferFor(ByteBuffer)), this will return a copy of the prefix with minimized values, otherwise it returns itself.
default java.nio.ByteBuffer	serializeAsPartitionKey()
int	size() The number of values in this prefix.
default java.lang.String	stringAt(int i, ClusteringComparator comparator)
java.lang.String	toString(TableMetadata metadata) Generates a proper string representation of the prefix.
default void	validate(int i, ClusteringComparator comparator)

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

isBottom

default boolean isBottom()

isTop

default boolean isTop()

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.

isEmpty

default boolean isEmpty()

get

V 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.

accessor

ValueAccessor<V> accessor()

bufferAt

default java.nio.ByteBuffer bufferAt(int i)

stringAt

default java.lang.String stringAt(int i,
                                  ClusteringComparator comparator)

validate

default void validate(int i,
                      ClusteringComparator comparator)

digest

default void digest(Digest digest)

Adds the data of this clustering prefix to the provided Digest instance.

Parameters:

digest - the Digest instance to which to add this prefix.

dataSize

default 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(TableMetadata 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.

serializeAsPartitionKey

default java.nio.ByteBuffer serializeAsPartitionKey()

getRawValues

V[] 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.

getBufferArray

java.nio.ByteBuffer[] getBufferArray()

minimize

ClusteringPrefix<V> minimize()

If the prefix contains byte buffers that can be minimized (see ByteBufferUtil.minimalBufferFor(ByteBuffer)), this will return a copy of the prefix with minimized values, otherwise it returns itself.

hashCode

static <V> int hashCode(ClusteringPrefix<V> prefix)

equals

static <V1,V2> boolean equals(ClusteringPrefix<V1> left,
                              ClusteringPrefix<V2> right)

equals

static boolean equals(ClusteringPrefix<?> prefix,
                      java.lang.Object o)