<HTML ><HEAD ><TITLE >Threading Behavior</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.73 "><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 7.3.2 Documentation" HREF="index.html"><LINK REL="UP" TITLE="libpq - C Library" HREF="libpq.html"><LINK REL="PREVIOUS" TITLE="Files" HREF="libpq-files.html"><LINK REL="NEXT" TITLE="Building Libpq Programs" HREF="libpq-build.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META NAME="creation" CONTENT="2003-02-03T20:17:34"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >PostgreSQL 7.3.2 Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="libpq-files.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 1. <SPAN CLASS="APPLICATION" >libpq</SPAN > - C Library</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="libpq-build.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="LIBPQ-THREADING" >1.12. Threading Behavior</A ></H1 ><A NAME="AEN25831" ></A ><P ><TT CLASS="FILENAME" >libpq</TT > is thread-safe as of <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > 7.0, so long as no two threads attempt to manipulate the same <TT CLASS="STRUCTNAME" >PGconn</TT > object at the same time. In particular, you cannot issue concurrent queries from different threads through the same connection object. (If you need to run concurrent queries, start up multiple connections.)</P ><P ><TT CLASS="STRUCTNAME" >PGresult</TT > objects are read-only after creation, and so can be passed around freely between threads.</P ><P >The deprecated functions <TT CLASS="FUNCTION" >PQoidStatus</TT > and <TT CLASS="FUNCTION" >fe_setauthsvc</TT > are not thread-safe and should not be used in multithread programs. <TT CLASS="FUNCTION" >PQoidStatus</TT > can be replaced by <TT CLASS="FUNCTION" >PQoidValue</TT >. There is no good reason to call <TT CLASS="FUNCTION" >fe_setauthsvc</TT > at all.</P ><P ><TT CLASS="FILENAME" >Libpq</TT > clients using the <TT CLASS="LITERAL" >crypt</TT > encryption method rely on the <TT CLASS="LITERAL" >crypt()</TT > operating system function, which is often not thread-safe. It is better to use <TT CLASS="LITERAL" >MD5</TT > encryption, which is thread-safe on all platforms.</P ></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-files.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-build.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Files</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="libpq.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Building <SPAN CLASS="APPLICATION" >Libpq</SPAN > Programs</TD ></TR ></TABLE ></DIV ></BODY ></HTML >
