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<title>Enable tracing a PostgreSQL connection</title>
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<h1 class="refname">pg_trace</h1>
<p class="verinfo">(PHP 4 >= 4.0.1, PHP 5)</p><p class="refpurpose"><span class="refname">pg_trace</span> — <span class="dc-title">Enable tracing a PostgreSQL connection</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.pg-trace-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>pg_trace</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$pathname</code></span>
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$mode</code><span class="initializer"> = "w"</span></span>
[, <span class="methodparam"><span class="type">resource</span> <code class="parameter">$connection</code></span>
]] )</div>
<p class="para rdfs-comment">
<span class="function"><strong>pg_trace()</strong></span> enables tracing of the PostgreSQL
frontend/backend communication to a file. To fully understand the results,
one needs to be familiar with the internals of PostgreSQL
communication protocol.
</p>
<p class="para">For those who are not, it can still be
useful for tracing errors in queries sent to the server, you
could do for example <strong class="command">grep '^To backend'
trace.log</strong> and see what queries actually were sent to the
PostgreSQL server. For more information, refer to the
<a href="http://www.postgresql.org/docs/current/interactive/" class="link external">» PostgreSQL Documentation</a>.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.pg-trace-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">pathname</code></em></span>
<dd>
<p class="para">
The full path and file name of the file in which to write the
trace log. Same as in <span class="function"><a href="function.fopen.html" class="function">fopen()</a></span>.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">mode</code></em></span>
<dd>
<p class="para">
An optional file access mode, same as for <span class="function"><a href="function.fopen.html" class="function">fopen()</a></span>.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">connection</code></em></span>
<dd>
<p class="para">
PostgreSQL database connection resource. When
<em><code class="parameter">connection</code></em> is not present, the default connection
is used. The default connection is the last connection made by
<span class="function"><a href="function.pg-connect.html" class="function">pg_connect()</a></span> or <span class="function"><a href="function.pg-pconnect.html" class="function">pg_pconnect()</a></span>.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.pg-trace-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> on success or <strong><code>FALSE</code></strong> on failure.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.pg-trace-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-2123">
<p><strong>Example #1 <span class="function"><strong>pg_trace()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$pgsql_conn </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">"dbname=mark host=localhost"</span><span style="color: #007700">);<br /><br />if (</span><span style="color: #0000BB">$pgsql_conn</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">pg_trace</span><span style="color: #007700">(</span><span style="color: #DD0000">'/tmp/trace.log'</span><span style="color: #007700">, </span><span style="color: #DD0000">'w'</span><span style="color: #007700">, </span><span style="color: #0000BB">$pgsql_conn</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">pg_query</span><span style="color: #007700">(</span><span style="color: #DD0000">"SELECT 1"</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">pg_untrace</span><span style="color: #007700">(</span><span style="color: #0000BB">$pgsql_conn</span><span style="color: #007700">);<br /> </span><span style="color: #FF8000">// Now /tmp/trace.log will contain backend communication<br /></span><span style="color: #007700">} else {<br /> print </span><span style="color: #0000BB">pg_last_error</span><span style="color: #007700">(</span><span style="color: #0000BB">$pgsql_conn</span><span style="color: #007700">);<br /> exit;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.pg-trace-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.fopen.html" class="function" rel="rdfs-seeAlso">fopen()</a> - Opens file or URL</span></li>
<li class="member"> <span class="function"><a href="function.pg-untrace.html" class="function" rel="rdfs-seeAlso">pg_untrace()</a> - Disable tracing of a PostgreSQL connection</span></li>
</ul>
</p>
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