it.unimi.di.big.mg4j.index.cluster

Interface DocumentalPartitioningStrategy

All Superinterfaces:

PartitioningStrategy, Serializable

All Known Implementing Classes:

ContiguousDocumentalStrategy

public interface DocumentalPartitioningStrategy
extends PartitioningStrategy

A way to associate a document with a local index out of a given set and a local document number in the local index.

When partitioning documentally an index, we need a way to associate to each global document pointer a local index (the index that will contain the postings of that document) and a local document pointer (the document pointer actually represented in the local index).

Usually, a documental partitioning strategy has a matching DocumentalClusteringStrategy whose methods satisfy the following equations:

 globalPointer(localIndex(d), localPointer(d)) = d
 <localIndex(globalPointer(i, l)), localPointer(globalPointer(i, l))> = <i, l>
 

Author:

Alessandro Arrabito, Sebastiano Vigna

Method Summary

Methods

Modifier and Type	Method and Description
int	localIndex(long globalPointer) Returns the index to which a given global document pointer is be mapped by this strategy.
long	localPointer(long globalPointer) Returns the local document pointer corresponding to a global document pointer.
long	numberOfDocuments(int localIndex) Returns the number of documents that will be assigned to the given local index.

Methods inherited from interface it.unimi.di.big.mg4j.index.cluster.PartitioningStrategy

numberOfLocalIndices, properties

Method Detail

localIndex

int localIndex(long globalPointer)

Returns the index to which a given global document pointer is be mapped by this strategy.

Parameters:

globalPointer - a global document pointer.

Returns:

the corresponding local index.

localPointer

long localPointer(long globalPointer)

Returns the local document pointer corresponding to a global document pointer.

Parameters:

globalPointer - a global document pointer.

Returns:

the corresponding local document pointer.

numberOfDocuments

long numberOfDocuments(int localIndex)

Returns the number of documents that will be assigned to the given local index.

Parameters:

localIndex - the local index.

Returns:

the number of documents that will be assigned to localIndex.