Package org.terrier.structures

Interface MetaIndex

All Superinterfaces:

java.lang.AutoCloseable, java.io.Closeable

All Known Implementing Classes:

BaseCompressingMetaIndex, CompressingMetaIndex, ConcurrentDecodingMetaIndex, LZ4CompressedMetaIndex, MemoryCompressedMetaIndex, MemoryMetaIndex, MemoryMetaIndexMap, MultiMeta, UncompressedMetaIndex, ZstdCompressedMetaIndex

public interface MetaIndex
extends java.io.Closeable

Interface for document metadata. Metadata is stored compressed on disk. Use the getItem() methods to get the metadata for a given document. Use the getDocument() method to determine docid for a given metadata value.

Examples:

 MetaIndex meta = index.getMetaIndex();
 //get docno of document with id 10
 String docno = meta.getItem("docno", 10);
 //get URL of document with id 100
 String url = meta.getItem("url", 100);
 //get docid of documet with url http://www.bbc.co.uk/
 int docid = meta.getDocument("url", "http://www.bbc.co.uk/");
 

Since:

3.0

Author:

Craig Macdonald

Method Summary

Modifier and Type	Method	Description
java.lang.String[]	getAllItems(int docid)	Obtain all metadata for specified document.
int	getDocument(java.lang.String key, java.lang.String value)	Obtain docid where document has specified metadata value in the specified type.
java.lang.String	getItem(java.lang.String Key, int docid)	Obtain metadata of specified type for specified document.
java.lang.String[]	getItems(java.lang.String[] keys, int docid)	Obtain metadata of specified types for specified document.
java.lang.String[][]	getItems(java.lang.String[] Key, int[] docids)	Obtain metadata of specified types for specified documents.
java.lang.String[]	getItems(java.lang.String Key, int[] docids)	Obtain metadata of specified type for specified documents.
java.lang.String[]	getKeys()	Returns the keys of this meta index
default java.lang.String[]	getReverseKeys()	Returns the reverse keys of this meta index
int	size()	How many documents in this metaindex

Methods inherited from interface java.io.Closeable

close

Method Detail

size

int size()

How many documents in this metaindex

getItem

java.lang.String getItem(java.lang.String Key,
                         int docid)
                  throws java.io.IOException

Obtain metadata of specified type for specified document.

Throws:

java.io.IOException

getAllItems

java.lang.String[] getAllItems(int docid)
                        throws java.io.IOException

Obtain all metadata for specified document.

Throws:

java.io.IOException

getItems

java.lang.String[] getItems(java.lang.String Key,
                            int[] docids)
                     throws java.io.IOException

Obtain metadata of specified type for specified documents.

Throws:

java.io.IOException

getItems

java.lang.String[] getItems(java.lang.String[] keys,
                            int docid)
                     throws java.io.IOException

Obtain metadata of specified types for specified document.

Throws:

java.io.IOException

getItems

java.lang.String[][] getItems(java.lang.String[] Key,
                              int[] docids)
                       throws java.io.IOException

Obtain metadata of specified types for specified documents. Return array is indexed by documents, then by metakeys.

Throws:

java.io.IOException

getDocument

int getDocument(java.lang.String key,
                java.lang.String value)
         throws java.io.IOException

Obtain docid where document has specified metadata value in the specified type. Returns -1 if the value cannot be found for the specified key type.

Throws:

java.io.IOException

getKeys

java.lang.String[] getKeys()

Returns the keys of this meta index

getReverseKeys

default java.lang.String[] getReverseKeys()

Returns the reverse keys of this meta index