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  1. <?xml version="1.0" encoding="UTF-8" standalone="no"?>

  2. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>33.10. Control Functions</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets V1.79.1" /><link rel="prev" href="libpq-copy.html" title="33.9. Functions Associated with the COPY Command" /><link rel="next" href="libpq-misc.html" title="33.11. Miscellaneous Functions" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">33.10. Control Functions</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="libpq-copy.html" title="33.9. Functions Associated with the COPY Command">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="libpq.html" title="Chapter 33. libpq - C Library">Up</a></td><th width="60%" align="center">Chapter 33. <span xmlns="http://www.w3.org/1999/xhtml" class="application">libpq</span> - C Library</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 12.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="libpq-misc.html" title="33.11. Miscellaneous Functions">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="LIBPQ-CONTROL"><div class="titlepage"><div><div><h2 class="title" style="clear: both">33.10. Control Functions</h2></div></div></div><p>

  3.    These functions control miscellaneous details of <span class="application">libpq</span>'s

  4.    behavior.

  5.   </p><div class="variablelist"><dl class="variablelist"><dt id="LIBPQ-PQCLIENTENCODING"><span class="term">

  6.      <code class="function">PQclientEncoding</code>

  7.      <a id="id-1.7.3.17.3.1.1.2" class="indexterm"></a>

  8.     </span></dt><dd><p>

  9.       Returns the client encoding.

  10. </p><pre class="synopsis">

  11. int PQclientEncoding(const PGconn *<em class="replaceable"><code>conn</code></em>);

  12. </pre><p>

  13. 

  14.       Note that it returns the encoding ID, not a symbolic string

  15.       such as <code class="literal">EUC_JP</code>. If unsuccessful, it returns -1.

  16.       To convert an encoding ID to an encoding name, you

  17.       can use:

  18. 

  19. </p><pre class="synopsis">

  20. char *pg_encoding_to_char(int <em class="replaceable"><code>encoding_id</code></em>);

  21. </pre><p>

  22.      </p></dd><dt id="LIBPQ-PQSETCLIENTENCODING"><span class="term">

  23.      <code class="function">PQsetClientEncoding</code>

  24.      <a id="id-1.7.3.17.3.2.1.2" class="indexterm"></a>

  25.     </span></dt><dd><p>

  26.       Sets the client encoding.

  27. </p><pre class="synopsis">

  28. int PQsetClientEncoding(PGconn *<em class="replaceable"><code>conn</code></em>, const char *<em class="replaceable"><code>encoding</code></em>);

  29. </pre><p>

  30. 

  31.       <em class="replaceable"><code>conn</code></em> is a connection to the server,

  32.       and <em class="replaceable"><code>encoding</code></em> is the encoding you want to

  33.       use. If the function successfully sets the encoding, it returns 0,

  34.       otherwise -1. The current encoding for this connection can be

  35.       determined by using <code class="function">PQclientEncoding</code>.

  36.      </p></dd><dt id="LIBPQ-PQSETERRORVERBOSITY"><span class="term">

  37.      <code class="function">PQsetErrorVerbosity</code>

  38.      <a id="id-1.7.3.17.3.3.1.2" class="indexterm"></a>

  39.     </span></dt><dd><p>

  40.       Determines the verbosity of messages returned by

  41.       <code class="function">PQerrorMessage</code> and <code class="function">PQresultErrorMessage</code>.

  42. </p><pre class="synopsis">

  43. typedef enum

  44. {

  45.     PQERRORS_TERSE,

  46.     PQERRORS_DEFAULT,

  47.     PQERRORS_VERBOSE,

  48.     PQERRORS_SQLSTATE

  49. } PGVerbosity;

  50. 

  51. PGVerbosity PQsetErrorVerbosity(PGconn *conn, PGVerbosity verbosity);

  52. </pre><p>

  53. 

  54.       <code class="function">PQsetErrorVerbosity</code> sets the verbosity mode,

  55.       returning the connection's previous setting.

  56.       In <em class="firstterm">TERSE</em> mode, returned messages include

  57.       severity, primary text, and position only; this will normally fit on a

  58.       single line.  The <em class="firstterm">DEFAULT</em> mode produces messages

  59.       that include the above plus any detail, hint, or context fields (these

  60.       might span multiple lines).  The <em class="firstterm">VERBOSE</em> mode

  61.       includes all available fields.  The <em class="firstterm">SQLSTATE</em>

  62.       mode includes only the error severity and the <code class="symbol">SQLSTATE</code>

  63.       error code, if one is available (if not, the output is like

  64.       <em class="firstterm">TERSE</em> mode).

  65.      </p><p>

  66.       Changing the verbosity setting does not affect the messages available

  67.       from already-existing <code class="structname">PGresult</code> objects, only

  68.       subsequently-created ones.

  69.       (But see <code class="function">PQresultVerboseErrorMessage</code> if you

  70.       want to print a previous error with a different verbosity.)

  71.      </p></dd><dt id="LIBPQ-PQSETERRORCONTEXTVISIBILITY"><span class="term">

  72.      <code class="function">PQsetErrorContextVisibility</code>

  73.      <a id="id-1.7.3.17.3.4.1.2" class="indexterm"></a>

  74.     </span></dt><dd><p>

  75.       Determines the handling of <code class="literal">CONTEXT</code> fields in messages

  76.       returned by <code class="function">PQerrorMessage</code>

  77.       and <code class="function">PQresultErrorMessage</code>.

  78. </p><pre class="synopsis">

  79. typedef enum

  80. {

  81.     PQSHOW_CONTEXT_NEVER,

  82.     PQSHOW_CONTEXT_ERRORS,

  83.     PQSHOW_CONTEXT_ALWAYS

  84. } PGContextVisibility;

  85. 

  86. PGContextVisibility PQsetErrorContextVisibility(PGconn *conn, PGContextVisibility show_context);

  87. </pre><p>

  88. 

  89.       <code class="function">PQsetErrorContextVisibility</code> sets the context display mode,

  90.       returning the connection's previous setting.  This mode controls

  91.       whether the <code class="literal">CONTEXT</code> field is included in messages.

  92.       The <em class="firstterm">NEVER</em> mode

  93.       never includes <code class="literal">CONTEXT</code>, while <em class="firstterm">ALWAYS</em> always

  94.       includes it if available.  In <em class="firstterm">ERRORS</em> mode (the

  95.       default), <code class="literal">CONTEXT</code> fields are included only in error

  96.       messages, not in notices and warnings.

  97.       (However, if the verbosity setting is <em class="firstterm">TERSE</em>

  98.       or <em class="firstterm">SQLSTATE</em>, <code class="literal">CONTEXT</code> fields

  99.       are omitted regardless of the context display mode.)

  100.      </p><p>

  101.       Changing this mode does not

  102.       affect the messages available from

  103.       already-existing <code class="structname">PGresult</code> objects, only

  104.       subsequently-created ones.

  105.       (But see <code class="function">PQresultVerboseErrorMessage</code> if you

  106.       want to print a previous error with a different display mode.)

  107.      </p></dd><dt id="LIBPQ-PQTRACE"><span class="term">

  108.      <code class="function">PQtrace</code>

  109.      <a id="id-1.7.3.17.3.5.1.2" class="indexterm"></a>

  110.     </span></dt><dd><p>

  111.       Enables  tracing of the client/server communication to a debugging file stream.

  112. </p><pre class="synopsis">

  113. void PQtrace(PGconn *conn, FILE *stream);

  114. </pre><p>

  115.      </p><div class="note"><h3 class="title">Note</h3><p>

  116.        On Windows, if the <span class="application">libpq</span> library and an application are

  117.        compiled with different flags, this function call will crash the

  118.        application because the internal representation of the <code class="literal">FILE</code>

  119.        pointers differ.  Specifically, multithreaded/single-threaded,

  120.        release/debug, and static/dynamic flags should be the same for the

  121.        library and all applications using that library.

  122.       </p></div></dd><dt id="LIBPQ-PQUNTRACE"><span class="term">

  123.      <code class="function">PQuntrace</code>

  124.      <a id="id-1.7.3.17.3.6.1.2" class="indexterm"></a>

  125.     </span></dt><dd><p>

  126.       Disables tracing started by <code class="function">PQtrace</code>.

  127. </p><pre class="synopsis">

  128. void PQuntrace(PGconn *conn);

  129. </pre><p>

  130.      </p></dd></dl></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="libpq-copy.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="libpq.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="libpq-misc.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">33.9. Functions Associated with the <code class="command">COPY</code> Command </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 33.11. Miscellaneous Functions</td></tr></table></div></body></html>
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