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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Control Functions</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 9.2.24 Documentation" HREF="index.html"><LINK REL="UP" TITLE="libpq - C Library" HREF="libpq.html"><LINK REL="PREVIOUS" TITLE="Functions Associated with the COPY Command" HREF="libpq-copy.html"><LINK REL="NEXT" TITLE="Miscellaneous Functions" HREF="libpq-misc.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2017-11-06T22:43:11"></HEAD ><BODY CLASS="SECT1" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" ><A HREF="index.html" >PostgreSQL 9.2.24 Documentation</A ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A TITLE="Functions Associated with the COPY Command" HREF="libpq-copy.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="libpq.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 31. <SPAN CLASS="APPLICATION" >libpq</SPAN > - C Library</TD ><TD WIDTH="20%" ALIGN="right" VALIGN="top" ><A TITLE="Miscellaneous Functions" HREF="libpq-misc.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="LIBPQ-CONTROL" >31.10. Control Functions</A ></H1 ><P > These functions control miscellaneous details of <SPAN CLASS="APPLICATION" >libpq</SPAN >'s behavior. </P ><P ></P ><DIV CLASS="VARIABLELIST" ><DL ><DT ><A NAME="LIBPQ-PQCLIENTENCODING" ></A ><CODE CLASS="FUNCTION" >PQclientEncoding</CODE > </DT ><DD ><P > Returns the client encoding. </P><PRE CLASS="SYNOPSIS" >int PQclientEncoding(const PGconn *<TT CLASS="REPLACEABLE" ><I >conn</I ></TT >);</PRE ><P> Note that it returns the encoding ID, not a symbolic string such as <TT CLASS="LITERAL" >EUC_JP</TT >. To convert an encoding ID to an encoding name, you can use: </P><PRE CLASS="SYNOPSIS" >char *pg_encoding_to_char(int <TT CLASS="REPLACEABLE" ><I >encoding_id</I ></TT >);</PRE ><P> </P ></DD ><DT ><A NAME="LIBPQ-PQSETCLIENTENCODING" ></A ><CODE CLASS="FUNCTION" >PQsetClientEncoding</CODE > </DT ><DD ><P > Sets the client encoding. </P><PRE CLASS="SYNOPSIS" >int PQsetClientEncoding(PGconn *<TT CLASS="REPLACEABLE" ><I >conn</I ></TT >, const char *<TT CLASS="REPLACEABLE" ><I >encoding</I ></TT >);</PRE ><P> <TT CLASS="REPLACEABLE" ><I >conn</I ></TT > is a connection to the server, and <TT CLASS="REPLACEABLE" ><I >encoding</I ></TT > is the encoding you want to use. If the function successfully sets the encoding, it returns 0, otherwise -1. The current encoding for this connection can be determined by using <CODE CLASS="FUNCTION" >PQclientEncoding</CODE >. </P ></DD ><DT ><A NAME="LIBPQ-PQSETERRORVERBOSITY" ></A ><CODE CLASS="FUNCTION" >PQsetErrorVerbosity</CODE > </DT ><DD ><P > Determines the verbosity of messages returned by <CODE CLASS="FUNCTION" >PQerrorMessage</CODE > and <CODE CLASS="FUNCTION" >PQresultErrorMessage</CODE >. </P><PRE CLASS="SYNOPSIS" >typedef enum { PQERRORS_TERSE, PQERRORS_DEFAULT, PQERRORS_VERBOSE } PGVerbosity; PGVerbosity PQsetErrorVerbosity(PGconn *conn, PGVerbosity verbosity);</PRE ><P> <CODE CLASS="FUNCTION" >PQsetErrorVerbosity</CODE > sets the verbosity mode, returning the connection's previous setting. In <I CLASS="FIRSTTERM" >TERSE</I > mode, returned messages include severity, primary text, and position only; this will normally fit on a single line. The default mode produces messages that include the above plus any detail, hint, or context fields (these might span multiple lines). The <I CLASS="FIRSTTERM" >VERBOSE</I > mode includes all available fields. Changing the verbosity does not affect the messages available from already-existing <TT CLASS="STRUCTNAME" >PGresult</TT > objects, only subsequently-created ones. </P ></DD ><DT ><A NAME="LIBPQ-PQTRACE" ></A ><CODE CLASS="FUNCTION" >PQtrace</CODE > </DT ><DD ><P > Enables tracing of the client/server communication to a debugging file stream. </P><PRE CLASS="SYNOPSIS" >void PQtrace(PGconn *conn, FILE *stream);</PRE ><P> </P ><DIV CLASS="NOTE" ><BLOCKQUOTE CLASS="NOTE" ><P ><B >Note: </B > On Windows, if the <SPAN CLASS="APPLICATION" >libpq</SPAN > library and an application are compiled with different flags, this function call will crash the application because the internal representation of the <TT CLASS="LITERAL" >FILE</TT > pointers differ. Specifically, multithreaded/single-threaded, release/debug, and static/dynamic flags should be the same for the library and all applications using that library. </P ></BLOCKQUOTE ></DIV ></DD ><DT ><A NAME="LIBPQ-PQUNTRACE" ></A ><CODE CLASS="FUNCTION" >PQuntrace</CODE > </DT ><DD ><P > Disables tracing started by <CODE CLASS="FUNCTION" >PQtrace</CODE >. </P><PRE CLASS="SYNOPSIS" >void PQuntrace(PGconn *conn);</PRE ><P> </P ></DD ></DL ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="libpq-copy.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="libpq-misc.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Functions Associated with the <TT CLASS="COMMAND" >COPY</TT > Command</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="libpq.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Miscellaneous Functions</TD ></TR ></TABLE ></DIV ></BODY ></HTML >