org.terrier.structures.indexing.singlepass

Class MemoryPostings

java.lang.Object

org.terrier.structures.indexing.singlepass.MemoryPostings

Direct Known Subclasses:

BlockMemoryPostings, FieldsMemoryPostings

public class MemoryPostings
extends Object

Class for handling Simple posting lists in memory while indexing.

Author:

Roi Blanco

Field Summary

Fields

Modifier and Type	Field and Description
protected long	keyBytes
protected static org.apache.log4j.Logger	logger logger to use in this class
protected int	maxSize The number of documents for any term in this run
protected long	numPointers Number of pointers ( tuples in memory in this run.
protected Map<String,Posting>	postings Hashmap indexed by the term, containing the posting lists
protected long	valueBytes

Constructor Summary

Constructors

Constructor and Description
MemoryPostings()

Method Summary

Methods

Modifier and Type	Method and Description
void	add(String term, int doc, int frequency) Adds an occurrence of a term in a document to the posting in memory.
void	addTerms(DocumentPostingList docPostings, int docid) Add the terms in a DocumentPostingList to the postings in memory.
void	finish(RunWriter runWriter) Triggers the writing of the postings in memory to the specified RunWriter.
void	finish(String[] file) Triggers the writing of the postings in memory to disk.
long	getMemoryConsumption() Returns the number of bytes consumed by this set of postings
long	getPointers() Returns the number of pointers in this posting list.
int	getSize() Returns the number of terms in this posting list.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

logger

protected static final org.apache.log4j.Logger logger

logger to use in this class

postings

protected Map<String,Posting> postings

Hashmap indexed by the term, containing the posting lists

maxSize

protected int maxSize

The number of documents for any term in this run

numPointers

protected long numPointers

Number of pointers ( tuples in memory in this run.

keyBytes

protected long keyBytes

valueBytes

protected long valueBytes

Constructor Detail

MemoryPostings

public MemoryPostings()

Method Detail

addTerms

public void addTerms(DocumentPostingList docPostings,
            int docid)
              throws IOException

Add the terms in a DocumentPostingList to the postings in memory.

Parameters:

docPostings - DocumentPostingList containing the term information for the denoted document.

docid - Current document Identifier.

Throws:

IOException - if an I/O error occurs.

add

public void add(String term,
       int doc,
       int frequency)
         throws IOException

Adds an occurrence of a term in a document to the posting in memory.

Parameters:

term - String representing the term.

doc - int containing the document identifier.

frequency - int containing the frequency of the term in the document.

Throws:

IOException - if an I/O error occurs.

finish

public void finish(String[] file)
            throws IOException

Triggers the writing of the postings in memory to disk. Uses the default RunWriter, writing to the specified files.

Parameters:

file - name of the file to write the postings.

Throws:

IOException - if an I/O error occurs.

finish

public void finish(RunWriter runWriter)
            throws IOException

Triggers the writing of the postings in memory to the specified RunWriter. If the RunWriter requires that terms are written in order, then this will happen.

Parameters:

runWriter -

Throws:

IOException

getSize

public int getSize()

Returns the number of terms in this posting list.

Returns:

the number of posting lists in memory.

getMemoryConsumption

public long getMemoryConsumption()

Returns the number of bytes consumed by this set of postings

getPointers

public long getPointers()

Returns the number of pointers in this posting list. Pointers are unique (term,docid) tuples.

Returns:

the number of pointers in memory.