A class to represent the per-PrimaryKey data in an index's postings file. More...

#include <postings_data.h>

Public Types
using	primary_key_type = PrimaryKey

using	secondary_key_type = SecondaryKey

using	pair_t = std::pair< SecondaryKey, double >

using	count_t = std::vector< pair_t >

Public Member Functions
	postings_data ()=default
	PrimaryKeys may only be integral types or strings; SecondaryKeys may only be integral types. More...

	postings_data (PrimaryKey p_id)
	Creates an empty postings_data for a given PrimaryKey. More...

void	merge_with (postings_data &other)

void	increase_count (SecondaryKey s_id, double amount)

double	count (SecondaryKey s_id) const

const count_t &	counts () const

void	set_counts (const count_t &counts)

bool	operator< (const postings_data &other) const

void	write_compressed (io::compressed_file_writer &writer) const
	Writes this postings_data to a compressed file. More...

void	read_compressed (io::compressed_file_reader &reader)
	Reads compressed postings_data into this object. More...

void	write_libsvm (std::ofstream &out) const

PrimaryKey	primary_key () const

void	set_primary_key (PrimaryKey new_key)

uint64_t	inverse_frequency () const

uint64_t	bytes_used () const

Private Attributes
PrimaryKey	p_id_
	Primary id this postings_data represents.

util::sparse_vector< SecondaryKey, double >	counts_
	The (secondary_key_type, count) pairs.

Static Private Attributes
static const uint64_t	delimiter_ = std::numeric_limits<uint64_t>::max()
	delimiter used when writing to compressed files

Friends
void	stream_helper (io::compressed_file_reader &in, postings_data< PrimaryKey, SecondaryKey > &pd)
	Helper function used by istream operator. More...

io::compressed_file_reader &	operator>> (io::compressed_file_reader &in, postings_data< PrimaryKey, SecondaryKey > &pd)
	Reads semi-compressed postings data from a compressed file. More...

io::compressed_file_writer &	operator<< (io::compressed_file_writer &out, const postings_data< PrimaryKey, SecondaryKey > &pd)
	Writes semi-compressed postings data to a compressed file. More...

Detailed Description

template<class PrimaryKey, class SecondaryKey>
class meta::index::postings_data< PrimaryKey, SecondaryKey >

A class to represent the per-PrimaryKey data in an index's postings file.

For a given PrimaryKey, a mapping of SecondaryKey -> count information is stored.

For example, for an inverted index, PrimaryKey = term_id, SecondaryKey = doc_id. For a forward_index, PrimaryKey = doc_id, SecondaryKey = term_id.

Constructor & Destructor Documentation

template<class PrimaryKey , class SecondaryKey >

meta::index::postings_data< PrimaryKey, SecondaryKey >::postings_data ( )

default

PrimaryKeys may only be integral types or strings; SecondaryKeys may only be integral types.

uint64_t and double must take up the same number of bytes since they are being casted to each other when compressing. postings_data is default-constructable.

template<class PrimaryKey , class SecondaryKey >

meta::index::postings_data< PrimaryKey, SecondaryKey >::postings_data ( PrimaryKey p_id )

Creates an empty postings_data for a given PrimaryKey.

Parameters

p_id	The PrimaryKey to be associated with this postings_data

Member Function Documentation

template<class PrimaryKey , class SecondaryKey >

void meta::index::postings_data< PrimaryKey, SecondaryKey >::merge_with ( postings_data< PrimaryKey, SecondaryKey > & other )

Parameters

other The other postings_data object to consume Adds the parameter's data to this object's data

template<class PrimaryKey , class SecondaryKey >

void meta::index::postings_data< PrimaryKey, SecondaryKey >::increase_count	(	SecondaryKey	s_id,
		double	amount
	)

Parameters

s_id	The SecondaryKey's id to add counts for
amount	The number of times to increase the count for a given SecondaryKey

template<class PrimaryKey , class SecondaryKey >

double meta::index::postings_data< PrimaryKey, SecondaryKey >::count ( SecondaryKey s_id ) const

Parameters

s_id	The SecondaryKey id to query

Returns: the number of times SecondaryKey occurred in this postings_data

template<class PrimaryKey , class SecondaryKey >

const std::vector< std::pair< SecondaryKey, double > > & meta::index::postings_data< PrimaryKey, SecondaryKey >::counts ( ) const

Returns: the per-SecondaryKey frequency information for this PrimaryKey

template<class PrimaryKey , class SecondaryKey >

void meta::index::postings_data< PrimaryKey, SecondaryKey >::set_counts ( const count_t & counts )

Parameters

counts A map of counts to assign into this postings_data

template<class PrimaryKey , class SecondaryKey >

bool meta::index::postings_data< PrimaryKey, SecondaryKey >::operator< ( const postings_data< PrimaryKey, SecondaryKey > & other ) const

Parameters

other The postings_data to compare with

Returns: whether this postings_data is less than (has a smaller PrimaryKey than) the parameter

template<class PrimaryKey , class SecondaryKey >

void meta::index::postings_data< PrimaryKey, SecondaryKey >::write_compressed ( io::compressed_file_writer & writer ) const

Writes this postings_data to a compressed file.

The mapping for the compressed file is already set, so we don't have to worry about it. We can also assume that we are already in the correct location of the file.

Parameters

writer The compressed file to write to

template<class PrimaryKey , class SecondaryKey >

void meta::index::postings_data< PrimaryKey, SecondaryKey >::read_compressed ( io::compressed_file_reader & reader )

Reads compressed postings_data into this object.

The mapping for the compressed file is already set, so we don't have to worry about it. We can also assume that we are already in the correct location of the file.

Parameters

reader The compressed file to read from

template<class PrimaryKey , class SecondaryKey >

void meta::index::postings_data< PrimaryKey, SecondaryKey >::write_libsvm ( std::ofstream & out ) const

inline

Parameters

out	The output stream to write to

template<class PrimaryKey , class SecondaryKey >

PrimaryKey meta::index::postings_data< PrimaryKey, SecondaryKey >::primary_key ( ) const

Returns: the term_id for this postings_data

template<class PrimaryKey , class SecondaryKey >

void meta::index::postings_data< PrimaryKey, SecondaryKey >::set_primary_key ( PrimaryKey new_key )

Parameters

new_key

template<class PrimaryKey , class SecondaryKey >

uint64_t meta::index::postings_data< PrimaryKey, SecondaryKey >::inverse_frequency ( ) const

Returns: the number of SecondaryKeys that this PrimaryKey occurs with

template<class PrimaryKey , class SecondaryKey >

uint64_t meta::index::postings_data< PrimaryKey, SecondaryKey >::bytes_used ( ) const

Returns: the number of bytes used for this postings_data

Friends And Related Function Documentation

template<class PrimaryKey , class SecondaryKey >

void stream_helper	(	io::compressed_file_reader &	in,
		postings_data< PrimaryKey, SecondaryKey > &	pd
	)

friend

Helper function used by istream operator.

Parameters

in	The stream to read from
pd	The postings data object to write the stream info to

template<class PrimaryKey , class SecondaryKey >

io::compressed_file_reader& operator>>	(	io::compressed_file_reader &	in,
		postings_data< PrimaryKey, SecondaryKey > &	pd
	)

friend

Reads semi-compressed postings data from a compressed file.

Parameters

in	The stream to read from
pd	The postings data object to write the stream info to

Returns: the input stream

template<class PrimaryKey , class SecondaryKey >

io::compressed_file_writer& operator<<	(	io::compressed_file_writer &	out,
		const postings_data< PrimaryKey, SecondaryKey > &	pd
	)

friend

Writes semi-compressed postings data to a compressed file.

Parameters

out	The stream to write to
pd	The postings data object to write to the stream

Returns: the output stream

The documentation for this class was generated from the following files:

/home/chase/projects/meta/include/index/forward_index.h
/home/chase/projects/meta/include/index/postings_data.h
/home/chase/projects/meta/include/index/postings_data.tcc

Public Types

Public Member Functions

Private Attributes

Static Private Attributes

Friends

Detailed Description

template<class PrimaryKey, class SecondaryKey> class meta::index::postings_data< PrimaryKey, SecondaryKey >

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation

template<class PrimaryKey, class SecondaryKey>
class meta::index::postings_data< PrimaryKey, SecondaryKey >