DBCacheTransactionShrinker Class Reference

This is the interface class of a database cacher, which enables transcation shrinking. More...

#include <DBCacheTransactionShrinker.hpp>

Inheritance diagram for DBCacheTransactionShrinker:

[legend]Collaboration diagram for DBCacheTransactionShrinker:

[legend]List of all members.

Public Types
typedef DBCache::params_t	params_t
Public Member Functions
	DBCacheTransactionShrinker (const params_t *par)
counter_t	nextTransactionBIS_modifyPrevious (BIS &transaction, std::vector< unsigned int > &filter)
	It returns the next transaction and modifies the previously returned transaction according to the filter.
void	setCandidateSize (const size_t candidate_size)
	This sets the size of the candidates.
template<class BIS>
counter_t	nextTransactionBIS (BIS &transaction)
template<class UAC>
bool	nextTransactionUAC (UAC &transaction)
void	rewind ()
	see: TransactionReader::rewind

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Detailed Description

This is the interface class of a database cacher, which enables transcation shrinking.

In the basic database cacher (see DBCache) it is not possible to modify the transactions that are stored in the cacher. Nevertheless it may significantly increase the efficiency if we could delete some item from certain transactions. For example unnecessary items slow down the support count of Apriori regardless of the data structure that is used to store the candidates.

An efficient transaction skrinking, which can be used in Apriori, was proposed by Park et al. It states that an item can be deleted from transaction t at iteration l, if it is not the element of l different candidates that are contained in t.

Definition at line 32 of file DBCacheTransactionShrinker.hpp.

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Member Typedef Documentation

typedef DBCache::params_t DBCacheTransactionShrinker::params_t

Reimplemented from DBCache< T_R >. Definition at line 35 of file DBCacheTransactionShrinker.hpp.

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Constructor & Destructor Documentation

DBCacheTransactionShrinker::DBCacheTransactionShrinker (  const params_t *  par  )  [inline]

Definition at line 36 of file DBCacheTransactionShrinker.hpp.

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Member Function Documentation

template<class T_R> template<class BIS> counter_t DBCache< T_R >::nextTransactionBIS (  BIS &  transaction  )  [inline, inherited]

Definition at line 55 of file DBCache.hpp.

counter_t DBCacheTransactionShrinker::nextTransactionBIS_modifyPrevious (  BIS &  transaction, std::vector< unsigned int > &  filter )

It returns the next transaction and modifies the previously returned transaction according to the filter. Parameters: transaction  the next transaction filter  the element of index i of the filter stores the number of candidates that contain item i and are contained in the previous transaction. According to the transaction shrinking proposed by Park et al. elements smaller than the size of the candidates can be removed from the transaction.

template<class T_R> template<class UAC> bool DBCache< T_R >::nextTransactionUAC (  UAC &  transaction  )  [inline, inherited]

Definition at line 58 of file DBCache.hpp.

template<class T_R> void DBCache< T_R >::rewind (   )  [inline, inherited]

see: TransactionReader::rewind Definition at line 62 of file DBCache.hpp.

void DBCacheTransactionShrinker::setCandidateSize (  const size_t  candidate_size  )

This sets the size of the candidates.

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

• DBCacheTransactionShrinker.hpp

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