classxapian_1_1database.tex

xapian 是一个“Xapian 是一个开源概率论信息检索库

\hypertarget{classXapian_1_1Database}{
\section{Xapian::Database Class Reference}
\label{classXapian_1_1Database}\index{Xapian::Database@{Xapian::Database}}
}
This class is used to access a database, or a group of databases.  


{\tt \#include $<$database.h$>$}

Inheritance diagram for Xapian::Database:\begin{figure}[H]
\begin{center}
\leavevmode
\includegraphics[width=86pt]{classXapian_1_1Database__inherit__graph}
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\subsection*{Public Member Functions}
\begin{CompactItemize}
\item 
void \hyperlink{classXapian_1_1Database_2fc5aa368a7097ca787a831211a2e3bc}{add\_\-database} (const \hyperlink{classXapian_1_1Database}{Database} \&database)
\begin{CompactList}\small\item\em Add an existing database (or group of databases) to those accessed by this object. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1Database_24f8197f3ac8bfd8c2526e0b8dff4ff7}{Database} ()
\begin{CompactList}\small\item\em Create a \hyperlink{classXapian_1_1Database}{Database} with no databases in. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1Database_b180b01a76a9d73a9315b181514a2f25}{Database} (const std::string \&path)
\begin{CompactList}\small\item\em Open a \hyperlink{classXapian_1_1Database}{Database}, automatically determining the database backend to use. \item\end{CompactList}\item 
\hypertarget{classXapian_1_1Database_7d737e6a640931dcb67c3e7eb702679c}{
{\bf Database} (Internal $\ast$internal)}
\label{classXapian_1_1Database_7d737e6a640931dcb67c3e7eb702679c}

\item 
virtual \hyperlink{classXapian_1_1Database_0352b3a47dca16d57c071252e84f1043}{$\sim$Database} ()
\begin{CompactList}\small\item\em Destroy this handle on the database. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1Database_aae498b70286ba1c588b7cbeb0972d38}{Database} (const \hyperlink{classXapian_1_1Database}{Database} \&other)
\begin{CompactList}\small\item\em Copying is allowed. \item\end{CompactList}\item 
void \hyperlink{classXapian_1_1Database_4e8badea7a9d7292c13f99429c6a2b79}{operator=} (const \hyperlink{classXapian_1_1Database}{Database} \&other)
\begin{CompactList}\small\item\em Assignment is allowed. \item\end{CompactList}\item 
void \hyperlink{classXapian_1_1Database_f140b1f8d948d13cf7be4a11a7c699a4}{reopen} ()
\begin{CompactList}\small\item\em Re-open the database. \item\end{CompactList}\item 
virtual std::string \hyperlink{classXapian_1_1Database_59e5889c489ce77fb4e7ffd80b6bc52c}{get\_\-description} () const 
\begin{CompactList}\small\item\em Introspection method. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1PostingIterator}{Posting\-Iterator} \hyperlink{classXapian_1_1Database_504d8e800384d12a8f9defee39362f5e}{postlist\_\-begin} (const std::string \&tname) const 
\begin{CompactList}\small\item\em An iterator pointing to the start of the postlist for a given term. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1PostingIterator}{Posting\-Iterator} \hyperlink{classXapian_1_1Database_c1661ac2876a4a69f327907ef47a003d}{postlist\_\-end} (const std::string \&) const 
\begin{CompactList}\small\item\em Corresponding end iterator to \hyperlink{classXapian_1_1Database_504d8e800384d12a8f9defee39362f5e}{postlist\_\-begin()}. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1TermIterator}{Term\-Iterator} \hyperlink{classXapian_1_1Database_c26b8f8f564c37586c7a0bd35cfefe15}{termlist\_\-begin} (\hyperlink{types_8h_53073891e45d892a8d8a5d8f87f41402}{Xapian::docid} did) const 
\begin{CompactList}\small\item\em An iterator pointing to the start of the termlist for a given document. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1TermIterator}{Term\-Iterator} \hyperlink{classXapian_1_1Database_a6f20c07f93d53f35caf6c97c795a5a1}{termlist\_\-end} (\hyperlink{types_8h_53073891e45d892a8d8a5d8f87f41402}{Xapian::docid}) const 
\begin{CompactList}\small\item\em Corresponding end iterator to \hyperlink{classXapian_1_1Database_c26b8f8f564c37586c7a0bd35cfefe15}{termlist\_\-begin()}. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1PositionIterator}{Position\-Iterator} \hyperlink{classXapian_1_1Database_9fb4987b5f0e13b8344a89d1898f5500}{positionlist\_\-begin} (\hyperlink{types_8h_53073891e45d892a8d8a5d8f87f41402}{Xapian::docid} did, const std::string \&tname) const 
\begin{CompactList}\small\item\em An iterator pointing to the start of the position list for a given term in a given document. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1PositionIterator}{Position\-Iterator} \hyperlink{classXapian_1_1Database_ef7093cb5cfd969c4b07593e26d208e3}{positionlist\_\-end} (\hyperlink{types_8h_53073891e45d892a8d8a5d8f87f41402}{Xapian::docid}, const std::string \&) const 
\begin{CompactList}\small\item\em Corresponding end iterator to \hyperlink{classXapian_1_1Database_9fb4987b5f0e13b8344a89d1898f5500}{positionlist\_\-begin()}. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1TermIterator}{Term\-Iterator} \hyperlink{classXapian_1_1Database_1bef542ac6af6749b95ba6547d5139fe}{allterms\_\-begin} () const 
\begin{CompactList}\small\item\em An iterator which runs across all terms in the database. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1TermIterator}{Term\-Iterator} \hyperlink{classXapian_1_1Database_03a144e5b1aa8104ea82aa5031ba2943}{allterms\_\-end} () const 
\begin{CompactList}\small\item\em Corresponding end iterator to \hyperlink{classXapian_1_1Database_1bef542ac6af6749b95ba6547d5139fe}{allterms\_\-begin()}. \item\end{CompactList}\item 
\hyperlink{types_8h_b4166dca4ac15d88c933bbb8e0d55d23}{Xapian::doccount} \hyperlink{classXapian_1_1Database_c13c9f754b55edf7e25d754a150bd970}{get\_\-doccount} () const 
\begin{CompactList}\small\item\em Get the number of documents in the database. \item\end{CompactList}\item 
\hyperlink{types_8h_53073891e45d892a8d8a5d8f87f41402}{Xapian::docid} \hyperlink{classXapian_1_1Database_0c180d6facca7ca0e8486e7b995a6747}{get\_\-lastdocid} () const 
\begin{CompactList}\small\item\em Get the highest document id which has been used in the database. \item\end{CompactList}\item 
\hyperlink{types_8h_7272583216038f810105df7dc927723c}{Xapian::doclength} \hyperlink{classXapian_1_1Database_7be264cfd482d19e6ca1c99382838032}{get\_\-avlength} () const 
\begin{CompactList}\small\item\em Get the average length of the documents in the database. \item\end{CompactList}\item 
\hyperlink{types_8h_b4166dca4ac15d88c933bbb8e0d55d23}{Xapian::doccount} \hyperlink{classXapian_1_1Database_61d9b1e634aff99280a5fcdfc5087cdc}{get\_\-termfreq} (const std::string \&tname) const 
\begin{CompactList}\small\item\em Get the number of documents in the database indexed by a given term. \item\end{CompactList}\item 
bool \hyperlink{classXapian_1_1Database_22509662f07387074beb1e9919e8e1e9}{term\_\-exists} (const std::string \&tname) const 
\begin{CompactList}\small\item\em Check if a given term exists in the database. \item\end{CompactList}\item 
\hyperlink{types_8h_6979d98ebbe67186bd31e5ee2a7585cb}{Xapian::termcount} \hyperlink{classXapian_1_1Database_eb8b2a78e6a7834bf0cc9e863bcfb95b}{get\_\-collection\_\-freq} (const std::string \&tname) const 
\begin{CompactList}\small\item\em Return the total number of occurrences of the given term. \item\end{CompactList}\item 
\hyperlink{types_8h_7272583216038f810105df7dc927723c}{Xapian::doclength} \hyperlink{classXapian_1_1Database_36b565741b2d7a5f0cfe600f811b13e7}{get\_\-doclength} (\hyperlink{types_8h_53073891e45d892a8d8a5d8f87f41402}{Xapian::docid} did) const 
\begin{CompactList}\small\item\em Get the length of a document. \item\end{CompactList}\item 
void \hyperlink{classXapian_1_1Database_759d1fde0d3d8a2ed74b83c0ebd10974}{keep\_\-alive} ()
\begin{CompactList}\small\item\em Send a \char`\"{}keep-alive\char`\"{} to remote databases to stop them timing out. \item\end{CompactList}\item 
\hyperlink{classXapian_1_1Document}{Xapian::Document} \hyperlink{classXapian_1_1Database_c36eafdcf748e11e533149674329f90b}{get\_\-document} (\hyperlink{types_8h_53073891e45d892a8d8a5d8f87f41402}{Xapian::docid} did) const 
\begin{CompactList}\small\item\em Get a document from the database, given its document id. \item\end{CompactList}\end{CompactItemize}
\subsection*{Public Attributes}
\begin{CompactItemize}
\item 
\hypertarget{classXapian_1_1Database_d0480f48d4eaea44c05c893260f9c05c}{
std::vector$<$ \hyperlink{classXapian_1_1Internal_1_1RefCntPtr}{Xapian::Internal::Ref\-Cnt\-Ptr}$<$ Internal $>$ $>$ {\bf internal}}
\label{classXapian_1_1Database_d0480f48d4eaea44c05c893260f9c05c}

\end{CompactItemize}


\subsection{Detailed Description}
This class is used to access a database, or a group of databases. 

For searching, this class is used in conjunction with an \hyperlink{classXapian_1_1Enquire}{Enquire} object.

\begin{Desc}
\item[Exceptions:]
\begin{description}
\item[{\em Invalid\-Argument\-Error}]will be thrown if an invalid argument is supplied, for example, an unknown database type.\item[{\em Database\-Opening\-Error}]may be thrown if the database cannot be opened (for example, a required file cannot be found). \end{description}
\end{Desc}




\subsection{Constructor \& Destructor Documentation}
\hypertarget{classXapian_1_1Database_24f8197f3ac8bfd8c2526e0b8dff4ff7}{
\index{Xapian::Database@{Xapian::Database}!Database@{Database}}
\index{Database@{Database}!Xapian::Database@{Xapian::Database}}
\subsubsection[Database]{\setlength{\rightskip}{0pt plus 5cm}Xapian::Database::Database ()}}
\label{classXapian_1_1Database_24f8197f3ac8bfd8c2526e0b8dff4ff7}


Create a \hyperlink{classXapian_1_1Database}{Database} with no databases in. 

\hypertarget{classXapian_1_1Database_b180b01a76a9d73a9315b181514a2f25}{
\index{Xapian::Database@{Xapian::Database}!Database@{Database}}
\index{Database@{Database}!Xapian::Database@{Xapian::Database}}
\subsubsection[Database]{\setlength{\rightskip}{0pt plus 5cm}Xapian::Database::Database (const std::string \& {\em path})}}
\label{classXapian_1_1Database_b180b01a76a9d73a9315b181514a2f25}


Open a \hyperlink{classXapian_1_1Database}{Database}, automatically determining the database backend to use. 

\begin{Desc}
\item[Parameters:]
\begin{description}
\item[{\em path}]directory that the database is stored in. \end{description}
\end{Desc}
\hypertarget{classXapian_1_1Database_0352b3a47dca16d57c071252e84f1043}{
\index{Xapian::Database@{Xapian::Database}!~Database@{$\sim$Database}}
\index{~Database@{$\sim$Database}!Xapian::Database@{Xapian::Database}}
\subsubsection[$\sim$Database]{\setlength{\rightskip}{0pt plus 5cm}virtual Xapian::Database::$\sim$Database ()\hspace{0.3cm}{\tt  \mbox{[}virtual\mbox{]}}}}
\label{classXapian_1_1Database_0352b3a47dca16d57c071252e84f1043}


Destroy this handle on the database. 

If there are no copies of this object remaining, the database(s) will be closed. \hypertarget{classXapian_1_1Database_aae498b70286ba1c588b7cbeb0972d38}{
\index{Xapian::Database@{Xapian::Database}!Database@{Database}}
\index{Database@{Database}!Xapian::Database@{Xapian::Database}}
\subsubsection[Database]{\setlength{\rightskip}{0pt plus 5cm}Xapian::Database::Database (const \hyperlink{classXapian_1_1Database}{Database} \& {\em other})}}
\label{classXapian_1_1Database_aae498b70286ba1c588b7cbeb0972d38}


Copying is allowed. 

The internals are reference counted, so copying is cheap. 

\subsection{Member Function Documentation}
\hypertarget{classXapian_1_1Database_2fc5aa368a7097ca787a831211a2e3bc}{
\index{Xapian::Database@{Xapian::Database}!add_database@{add\_\-database}}
\index{add_database@{add\_\-database}!Xapian::Database@{Xapian::Database}}
\subsubsection[add\_\-database]{\setlength{\rightskip}{0pt plus 5cm}void Xapian::Database::add\_\-database (const \hyperlink{classXapian_1_1Database}{Database} \& {\em database})}}
\label{classXapian_1_1Database_2fc5aa368a7097ca787a831211a2e3bc}


Add an existing database (or group of databases) to those accessed by this object. 

\begin{Desc}
\item[Parameters:]
\begin{description}
\item[{\em database}]the database(s) to add. \end{description}
\end{Desc}
\hypertarget{classXapian_1_1Database_1bef542ac6af6749b95ba6547d5139fe}{
\index{Xapian::Database@{Xapian::Database}!allterms_begin@{allterms\_\-begin}}
\index{allterms_begin@{allterms\_\-begin}!Xapian::Database@{Xapian::Database}}
\subsubsection[allterms\_\-begin]{\setlength{\rightskip}{0pt plus 5cm}\hyperlink{classXapian_1_1TermIterator}{Term\-Iterator} Xapian::Database::allterms\_\-begin () const}}
\label{classXapian_1_1Database_1bef542ac6af6749b95ba6547d5139fe}


An iterator which runs across all terms in the database. 

\hypertarget{classXapian_1_1Database_03a144e5b1aa8104ea82aa5031ba2943}{
\index{Xapian::Database@{Xapian::Database}!allterms_end@{allterms\_\-end}}
\index{allterms_end@{allterms\_\-end}!Xapian::Database@{Xapian::Database}}
\subsubsection[allterms\_\-end]{\setlength{\rightskip}{0pt plus 5cm}\hyperlink{classXapian_1_1TermIterator}{Term\-Iterator} Xapian::Database::allterms\_\-end () const\hspace{0.3cm}{\tt  \mbox{[}inline\mbox{]}}}}
\label{classXapian_1_1Database_03a144e5b1aa8104ea82aa5031ba2943}


Corresponding end iterator to \hyperlink{classXapian_1_1Database_1bef542ac6af6749b95ba6547d5139fe}{allterms\_\-begin()}. 

\hypertarget{classXapian_1_1Database_7be264cfd482d19e6ca1c99382838032}{
\index{Xapian::Database@{Xapian::Database}!get_avlength@{get\_\-avlength}}
\index{get_avlength@{get\_\-avlength}!Xapian::Database@{Xapian::Database}}
\subsubsection[get\_\-avlength]{\setlength{\rightskip}{0pt plus 5cm}\hyperlink{types_8h_7272583216038f810105df7dc927723c}{Xapian::doclength} Xapian::Database::get\_\-avlength () const}}
\label{classXapian_1_1Database_7be264cfd482d19e6ca1c99382838032}


Get the average length of the documents in the database. 

\hypertarget{classXapian_1_1Database_eb8b2a78e6a7834bf0cc9e863bcfb95b}{