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  <div class="section" id="module-psycopg2.extensions">
<span id="psycopg2-extensions-extensions-to-the-db-api"></span><h1><a class="reference internal" href="#module-psycopg2.extensions" title="psycopg2.extensions"><tt class="xref py py-obj docutils literal"><span class="pre">psycopg2.extensions</span></tt></a> &#8211; Extensions to the DB API<a class="headerlink" href="#module-psycopg2.extensions" title="Permalink to this headline"></a></h1>
<p>The module contains a few objects and function extending the minimum set of
functionalities defined by the <a class="reference external" href="http://www.python.org/dev/peps/pep-0249/">DB API 2.0</a>.</p>
<dl class="class">
<dt id="psycopg2.extensions.connection">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">connection</tt><a class="headerlink" href="#psycopg2.extensions.connection" title="Permalink to this definition"></a></dt>
<dd><p>Is the class usually returned by the <a class="reference internal" href="module.html#psycopg2.connect" title="psycopg2.connect"><tt class="xref py py-obj docutils literal"><span class="pre">connect()</span></tt></a> function.
It is exposed by the <tt class="xref py py-obj docutils literal"><span class="pre">extensions</span></tt> module in order to allow
subclassing to extend its behaviour: the subclass should be passed to the
<tt class="xref py py-obj docutils literal"><span class="pre">connect()</span></tt> function using the <tt class="xref py py-obj docutils literal"><span class="pre">connection_factory</span></tt> parameter.
See also <a class="reference internal" href="advanced.html#subclassing-connection"><em>Connection and cursor factories</em></a>.</p>
<p>Subclasses should have constructor signature <tt class="samp docutils literal"><span class="pre">(</span><em><span class="pre">dsn</span></em><span class="pre">,</span> <em><span class="pre">async</span></em><span class="pre">=0)</span></tt>.</p>
<p>For a complete description of the class, see <a class="reference internal" href="connection.html#connection" title="connection"><tt class="xref py py-obj docutils literal"><span class="pre">connection</span></tt></a>.</p>
</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.cursor">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">cursor</tt><a class="headerlink" href="#psycopg2.extensions.cursor" title="Permalink to this definition"></a></dt>
<dd><p>It is the class usually returnded by the <a class="reference internal" href="connection.html#connection.cursor" title="connection.cursor"><tt class="xref py py-obj docutils literal"><span class="pre">connection.cursor()</span></tt></a>
method. It is exposed by the <tt class="xref py py-obj docutils literal"><span class="pre">extensions</span></tt> module in order to allow
subclassing to extend its behaviour: the subclass should be passed to the
<tt class="xref py py-obj docutils literal"><span class="pre">cursor()</span></tt> method using the <tt class="xref py py-obj docutils literal"><span class="pre">cursor_factory</span></tt> parameter. See
also <a class="reference internal" href="advanced.html#subclassing-cursor"><em>Connection and cursor factories</em></a>.</p>
<p>For a complete description of the class, see <a class="reference internal" href="cursor.html#cursor" title="cursor"><tt class="xref py py-obj docutils literal"><span class="pre">cursor</span></tt></a>.</p>
</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.lobject">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">lobject</tt><big>(</big><em>conn</em><span class="optional">[</span>, <em>oid</em><span class="optional">[</span>, <em>mode</em><span class="optional">[</span>, <em>new_oid</em><span class="optional">[</span>, <em>new_file</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#psycopg2.extensions.lobject" title="Permalink to this definition"></a></dt>
<dd><p>Wrapper for a PostgreSQL large object. See <a class="reference internal" href="usage.html#large-objects"><em>Access to PostgreSQL large objects</em></a> for an
overview.</p>
<p>The class can be subclassed: see the <a class="reference internal" href="connection.html#connection.lobject" title="connection.lobject"><tt class="xref py py-obj docutils literal"><span class="pre">connection.lobject()</span></tt></a> to know
how to specify a <tt class="xref py py-obj docutils literal"><span class="pre">lobject</span></tt> subclass.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.0.8.</span></p>
</div>
<dl class="attribute">
<dt id="psycopg2.extensions.lobject.oid">
<tt class="descname">oid</tt><a class="headerlink" href="#psycopg2.extensions.lobject.oid" title="Permalink to this definition"></a></dt>
<dd><p>Database OID of the object.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.lobject.mode">
<tt class="descname">mode</tt><a class="headerlink" href="#psycopg2.extensions.lobject.mode" title="Permalink to this definition"></a></dt>
<dd><p>The mode the database was open. See <a class="reference internal" href="connection.html#connection.lobject" title="connection.lobject"><tt class="xref py py-obj docutils literal"><span class="pre">connection.lobject()</span></tt></a> for a
description of the available modes.</p>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.lobject.read">
<tt class="descname">read</tt><big>(</big><em>bytes=-1</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.lobject.read" title="Permalink to this definition"></a></dt>
<dd><p>Read a chunk of data from the current file position. If -1 (default)
read all the remaining data.</p>
<p>The result is an Unicode string (decoded according to
<a class="reference internal" href="connection.html#connection.encoding" title="connection.encoding"><tt class="xref py py-obj docutils literal"><span class="pre">connection.encoding</span></tt></a>) if the file was open in <tt class="docutils literal"><span class="pre">t</span></tt> mode, a bytes
string for <tt class="docutils literal"><span class="pre">b</span></tt> mode.</p>
<div class="versionchanged">
<p><span class="versionmodified">Changed in version 2.4: </span>added Unicode support.</p>
</div>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.lobject.write">
<tt class="descname">write</tt><big>(</big><em>str</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.lobject.write" title="Permalink to this definition"></a></dt>
<dd><p>Write a string to the large object. Return the number of bytes
written. Unicode strings are encoded in the <a class="reference internal" href="connection.html#connection.encoding" title="connection.encoding"><tt class="xref py py-obj docutils literal"><span class="pre">connection.encoding</span></tt></a>
before writing.</p>
<div class="versionchanged">
<p><span class="versionmodified">Changed in version 2.4: </span>added Unicode support.</p>
</div>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.lobject.export">
<tt class="descname">export</tt><big>(</big><em>file_name</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.lobject.export" title="Permalink to this definition"></a></dt>
<dd><p>Export the large object content to the file system.</p>
<p>The method uses the efficient <a class="reference external" href="http://www.postgresql.org/docs/current/static/lo-interfaces.html#LO-EXPORT"><tt class="xref py py-obj docutils literal"><span class="pre">lo_export()</span></tt></a> libpq function.</p>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.lobject.seek">
<tt class="descname">seek</tt><big>(</big><em>offset</em>, <em>whence=0</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.lobject.seek" title="Permalink to this definition"></a></dt>
<dd><p>Set the lobject current position.</p>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.lobject.tell">
<tt class="descname">tell</tt><big>(</big><big>)</big><a class="headerlink" href="#psycopg2.extensions.lobject.tell" title="Permalink to this definition"></a></dt>
<dd><p>Return the lobject current position.</p>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.lobject.truncate">
<tt class="descname">truncate</tt><big>(</big><em>len=0</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.lobject.truncate" title="Permalink to this definition"></a></dt>
<dd><div class="versionadded">
<p><span class="versionmodified">New in version 2.2.0.</span></p>
</div>
<p>Truncate the lobject to the given size.</p>
<p>The method will only be available if Psycopg has been built against libpq
from PostgreSQL 8.3 or later and can only be used with PostgreSQL servers
running these versions. It uses the <a class="reference external" href="http://www.postgresql.org/docs/current/static/lo-interfaces.html#LO-TRUNCATE"><tt class="xref py py-obj docutils literal"><span class="pre">lo_truncate()</span></tt></a> libpq function.</p>
<div class="admonition warning">
<p class="first admonition-title">Warning</p>
<p class="last">If Psycopg is built with <tt class="xref py py-obj docutils literal"><span class="pre">lo_truncate()</span></tt> support (i.e. if the
<strong class="program">pg_config</strong> used during setup is version &gt;= 8.3), but at
runtime an older libpq is found, Psycopg will fail to import.  See
<a class="reference internal" href="faq.html#faq-lo-truncate"><em>the lo_truncate FAQ</em></a> about the problem.</p>
</div>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.lobject.close">
<tt class="descname">close</tt><big>(</big><big>)</big><a class="headerlink" href="#psycopg2.extensions.lobject.close" title="Permalink to this definition"></a></dt>
<dd><p>Close the object.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.lobject.closed">
<tt class="descname">closed</tt><a class="headerlink" href="#psycopg2.extensions.lobject.closed" title="Permalink to this definition"></a></dt>
<dd><p>Boolean attribute specifying if the object is closed.</p>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.lobject.unlink">
<tt class="descname">unlink</tt><big>(</big><big>)</big><a class="headerlink" href="#psycopg2.extensions.lobject.unlink" title="Permalink to this definition"></a></dt>
<dd><p>Close the object and remove it from the database.</p>
</dd></dl>

</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.Notify">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">Notify</tt><big>(</big><em>pid</em>, <em>channel</em>, <em>payload=''</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.Notify" title="Permalink to this definition"></a></dt>
<dd><p>A notification received from the backend.</p>
<p><tt class="xref py py-obj docutils literal"><span class="pre">Notify</span></tt> instances are made available upon reception on the
<a class="reference internal" href="connection.html#connection.notifies" title="connection.notifies"><tt class="xref py py-obj docutils literal"><span class="pre">notifies</span></tt></a> member of the listening connection. The object
can be also accessed as a 2 items tuple returning the members
<tt class="samp docutils literal"><span class="pre">(</span><em><span class="pre">pid</span></em><span class="pre">,</span><em><span class="pre">channel</span></em><span class="pre">)</span></tt> for backward compatibility.</p>
<p>See <a class="reference internal" href="advanced.html#async-notify"><em>Asynchronous notifications</em></a> for details.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.3.</span></p>
</div>
<dl class="attribute">
<dt id="psycopg2.extensions.Notify.channel">
<tt class="descname">channel</tt><a class="headerlink" href="#psycopg2.extensions.Notify.channel" title="Permalink to this definition"></a></dt>
<dd><p>The name of the channel to which the notification was sent.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.Notify.payload">
<tt class="descname">payload</tt><a class="headerlink" href="#psycopg2.extensions.Notify.payload" title="Permalink to this definition"></a></dt>
<dd><p>The payload message of the notification.</p>
<p>Attaching a payload to a notification is only available since
PostgreSQL 9.0: for notifications received from previous versions
of the server this member is always the empty string.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.Notify.pid">
<tt class="descname">pid</tt><a class="headerlink" href="#psycopg2.extensions.Notify.pid" title="Permalink to this definition"></a></dt>
<dd><p>The ID of the backend process that sent the notification.</p>
<p>Note: if the sending session was handled by Psycopg, you can use
<a class="reference internal" href="connection.html#connection.get_backend_pid" title="connection.get_backend_pid"><tt class="xref py py-obj docutils literal"><span class="pre">get_backend_pid()</span></tt></a> to know its PID.</p>
</dd></dl>

</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.Xid">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">Xid</tt><big>(</big><em>format_id</em>, <em>gtrid</em>, <em>bqual</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.Xid" title="Permalink to this definition"></a></dt>
<dd><p>A transaction identifier used for two-phase commit.</p>
<p>Usually returned by the connection methods <a class="reference internal" href="connection.html#connection.xid" title="connection.xid"><tt class="xref py py-obj docutils literal"><span class="pre">xid()</span></tt></a> and
<a class="reference internal" href="connection.html#connection.tpc_recover" title="connection.tpc_recover"><tt class="xref py py-obj docutils literal"><span class="pre">tpc_recover()</span></tt></a>.
<tt class="xref py py-obj docutils literal"><span class="pre">Xid</span></tt> instances can be unpacked as a 3-item tuples containing the items
<tt class="samp docutils literal"><span class="pre">(</span><em><span class="pre">format_id</span></em><span class="pre">,</span><em><span class="pre">gtrid</span></em><span class="pre">,</span><em><span class="pre">bqual</span></em><span class="pre">)</span></tt>.
The <tt class="xref py py-obj docutils literal"><span class="pre">str()</span></tt> of the object returns the <em>transaction ID</em> used
in the commands sent to the server.</p>
<p>See <a class="reference internal" href="usage.html#tpc"><em>Two-Phase Commit protocol support</em></a> for an introduction.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.3.</span></p>
</div>
<dl class="method">
<dt id="psycopg2.extensions.Xid.from_string">
<tt class="descname">from_string</tt><big>(</big><em>s</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.Xid.from_string" title="Permalink to this definition"></a></dt>
<dd><p>Create a <tt class="xref py py-obj docutils literal"><span class="pre">Xid</span></tt> object from a string representation. Static method.</p>
<p>If <em>s</em> is a PostgreSQL transaction ID produced by a XA transaction,
the returned object will have <a class="reference internal" href="#psycopg2.extensions.Xid.format_id" title="psycopg2.extensions.Xid.format_id"><tt class="xref py py-obj docutils literal"><span class="pre">format_id</span></tt></a>, <a class="reference internal" href="#psycopg2.extensions.Xid.gtrid" title="psycopg2.extensions.Xid.gtrid"><tt class="xref py py-obj docutils literal"><span class="pre">gtrid</span></tt></a>, <a class="reference internal" href="#psycopg2.extensions.Xid.bqual" title="psycopg2.extensions.Xid.bqual"><tt class="xref py py-obj docutils literal"><span class="pre">bqual</span></tt></a> set to
the values of the preparing XA id.
Otherwise only the <tt class="xref py py-obj docutils literal"><span class="pre">gtrid</span></tt> is populated with the unparsed string.
The operation is the inverse of the one performed by <tt class="xref py py-obj docutils literal"><span class="pre">str(xid)</span></tt>.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.Xid.bqual">
<tt class="descname">bqual</tt><a class="headerlink" href="#psycopg2.extensions.Xid.bqual" title="Permalink to this definition"></a></dt>
<dd><p>Branch qualifier of the transaction.</p>
<p>In a XA transaction every resource participating to a transaction
receives a distinct branch qualifier.
<tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt> if the transaction doesn&#8217;t follow the XA standard.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.Xid.database">
<tt class="descname">database</tt><a class="headerlink" href="#psycopg2.extensions.Xid.database" title="Permalink to this definition"></a></dt>
<dd><p>Database the recovered transaction belongs to.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.Xid.format_id">
<tt class="descname">format_id</tt><a class="headerlink" href="#psycopg2.extensions.Xid.format_id" title="Permalink to this definition"></a></dt>
<dd><p>Format ID in a XA transaction.</p>
<p>A non-negative 32 bit integer.
<tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt> if the transaction doesn&#8217;t follow the XA standard.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.Xid.gtrid">
<tt class="descname">gtrid</tt><a class="headerlink" href="#psycopg2.extensions.Xid.gtrid" title="Permalink to this definition"></a></dt>
<dd><p>Global transaction ID in a XA transaction.</p>
<p>If the transaction doesn&#8217;t follow the XA standard, it is the plain
<em>transaction ID</em> used in the server commands.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.Xid.owner">
<tt class="descname">owner</tt><a class="headerlink" href="#psycopg2.extensions.Xid.owner" title="Permalink to this definition"></a></dt>
<dd><p>Name of the user who prepared a recovered transaction.</p>
</dd></dl>

<dl class="attribute">
<dt id="psycopg2.extensions.Xid.prepared">
<tt class="descname">prepared</tt><a class="headerlink" href="#psycopg2.extensions.Xid.prepared" title="Permalink to this definition"></a></dt>
<dd><p>Timestamp (with timezone) in which a recovered transaction was prepared.</p>
</dd></dl>

</dd></dl>

<dl class="function">
<dt id="psycopg2.extensions.set_wait_callback">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">set_wait_callback</tt><big>(</big><em>f</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.set_wait_callback" title="Permalink to this definition"></a></dt>
<dd><p>Register a callback function to block waiting for data.</p>
<p>The callback should have signature <tt class="samp docutils literal"><span class="pre">fun(</span><em><span class="pre">conn</span></em><span class="pre">)</span></tt> and
is called to wait for data available whenever a blocking function from the
libpq is called.  Use <tt class="xref py py-obj docutils literal"><span class="pre">set_wait_callback(None)</span></tt> to revert to the
original behaviour (i.e. using blocking libpq functions).</p>
<p>The function is an hook to allow coroutine-based libraries (such as
<a class="reference external" href="http://eventlet.net/">Eventlet</a> or <a class="reference external" href="http://www.gevent.org/">gevent</a>) to switch when Psycopg is blocked, allowing
other coroutines to run concurrently.</p>
<p>See <a class="reference internal" href="extras.html#psycopg2.extras.wait_select" title="psycopg2.extras.wait_select"><tt class="xref py py-obj docutils literal"><span class="pre">wait_select()</span></tt></a> for an example of a wait callback
implementation.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.2.0.</span></p>
</div>
</dd></dl>

<dl class="function">
<dt id="psycopg2.extensions.get_wait_callback">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">get_wait_callback</tt><big>(</big><big>)</big><a class="headerlink" href="#psycopg2.extensions.get_wait_callback" title="Permalink to this definition"></a></dt>
<dd><p>Return the currently registered wait callback.</p>
<p>Return <tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt> if no callback is currently registered.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.2.0.</span></p>
</div>
</dd></dl>

<div class="section" id="sql-adaptation-protocol-objects">
<span id="sql-adaptation-objects"></span><h2>SQL adaptation protocol objects<a class="headerlink" href="#sql-adaptation-protocol-objects" title="Permalink to this headline"></a></h2>
<p>Psycopg provides a flexible system to adapt Python objects to the SQL syntax
(inspired to the <span class="target" id="index-0"></span><a class="pep reference external" href="http://www.python.org/dev/peps/pep-0246"><strong>PEP 246</strong></a>), allowing serialization in PostgreSQL. See
<a class="reference internal" href="advanced.html#adapting-new-types"><em>Adapting new Python types to SQL syntax</em></a> for a detailed description.  The following objects
deal with Python objects adaptation:</p>
<dl class="function">
<dt id="psycopg2.extensions.adapt">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">adapt</tt><big>(</big><em>obj</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.adapt" title="Permalink to this definition"></a></dt>
<dd><p>Return the SQL representation of <em>obj</em> as a string.  Raise a
<a class="reference internal" href="module.html#psycopg2.ProgrammingError" title="psycopg2.ProgrammingError"><tt class="xref py py-obj docutils literal"><span class="pre">ProgrammingError</span></tt></a> if how to adapt the object is unknown.
In order to allow new objects to be adapted, register a new adapter for it
using the <a class="reference internal" href="#psycopg2.extensions.register_adapter" title="psycopg2.extensions.register_adapter"><tt class="xref py py-obj docutils literal"><span class="pre">register_adapter()</span></tt></a> function.</p>
<p>The function is the entry point of the adaptation mechanism: it can be
used to write adapters for complex objects by recursively calling
<tt class="xref py py-obj docutils literal"><span class="pre">adapt()</span></tt> on its components.</p>
</dd></dl>

<dl class="function">
<dt id="psycopg2.extensions.register_adapter">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">register_adapter</tt><big>(</big><em>class</em>, <em>adapter</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.register_adapter" title="Permalink to this definition"></a></dt>
<dd><p>Register a new adapter for the objects of class <em>class</em>.</p>
<p><em>adapter</em> should be a function taking a single argument (the object
to adapt) and returning an object conforming the <a class="reference internal" href="#psycopg2.extensions.ISQLQuote" title="psycopg2.extensions.ISQLQuote"><tt class="xref py py-obj docutils literal"><span class="pre">ISQLQuote</span></tt></a>
protocol (e.g. exposing a <tt class="xref py py-obj docutils literal"><span class="pre">getquoted()</span></tt> method).  The <a class="reference internal" href="#psycopg2.extensions.AsIs" title="psycopg2.extensions.AsIs"><tt class="xref py py-obj docutils literal"><span class="pre">AsIs</span></tt></a> is
often useful for this task.</p>
<p>Once an object is registered, it can be safely used in SQL queries and by
the <a class="reference internal" href="#psycopg2.extensions.adapt" title="psycopg2.extensions.adapt"><tt class="xref py py-obj docutils literal"><span class="pre">adapt()</span></tt></a> function.</p>
</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.ISQLQuote">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">ISQLQuote</tt><big>(</big><em>wrapped_object</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.ISQLQuote" title="Permalink to this definition"></a></dt>
<dd><p>Represents the SQL adaptation protocol.  Objects conforming this protocol
should implement a <a class="reference internal" href="#psycopg2.extensions.ISQLQuote.getquoted" title="psycopg2.extensions.ISQLQuote.getquoted"><tt class="xref py py-obj docutils literal"><span class="pre">getquoted()</span></tt></a> and optionally a <a class="reference internal" href="#psycopg2.extensions.ISQLQuote.prepare" title="psycopg2.extensions.ISQLQuote.prepare"><tt class="xref py py-obj docutils literal"><span class="pre">prepare()</span></tt></a> method.</p>
<p>Adapters may subclass <tt class="xref py py-obj docutils literal"><span class="pre">ISQLQuote</span></tt>, but is not necessary: it is
enough to expose a <tt class="xref py py-obj docutils literal"><span class="pre">getquoted()</span></tt> method to be conforming.</p>
<dl class="attribute">
<dt id="psycopg2.extensions.ISQLQuote._wrapped">
<tt class="descname">_wrapped</tt><a class="headerlink" href="#psycopg2.extensions.ISQLQuote._wrapped" title="Permalink to this definition"></a></dt>
<dd><p>The wrapped object passes to the constructor</p>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.ISQLQuote.getquoted">
<tt class="descname">getquoted</tt><big>(</big><big>)</big><a class="headerlink" href="#psycopg2.extensions.ISQLQuote.getquoted" title="Permalink to this definition"></a></dt>
<dd><p>Subclasses or other conforming objects should return a valid SQL
string representing the wrapped object. In Python 3 the SQL must be
returned in a <tt class="xref py py-obj docutils literal"><span class="pre">bytes</span></tt> object. The <tt class="xref py py-obj docutils literal"><span class="pre">ISQLQuote</span></tt> implementation does
nothing.</p>
</dd></dl>

<dl class="method">
<dt id="psycopg2.extensions.ISQLQuote.prepare">
<tt class="descname">prepare</tt><big>(</big><em>conn</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.ISQLQuote.prepare" title="Permalink to this definition"></a></dt>
<dd><p>Prepare the adapter for a connection.  The method is optional: if
implemented, it will be invoked before <tt class="xref py py-obj docutils literal"><span class="pre">getquoted()</span></tt> with the
connection to adapt for as argument.</p>
<p>A conform object can implement this method if the SQL
representation depends on any server parameter, such as the server
version or the <span class="target" id="index-1"></span><tt class="xref std std-envvar docutils literal"><span class="pre">standard_conforming_string</span></tt> setting.  Container
objects may store the connection and use it to recursively prepare
contained objects: see the implementation for
<a class="reference internal" href="#psycopg2.extensions.SQL_IN" title="psycopg2.extensions.SQL_IN"><tt class="xref py py-obj docutils literal"><span class="pre">psycopg2.extensions.SQL_IN</span></tt></a> for a simple example.</p>
</dd></dl>

</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.AsIs">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">AsIs</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.AsIs" title="Permalink to this definition"></a></dt>
<dd><p>Adapter conform to the <a class="reference internal" href="#psycopg2.extensions.ISQLQuote" title="psycopg2.extensions.ISQLQuote"><tt class="xref py py-obj docutils literal"><span class="pre">ISQLQuote</span></tt></a> protocol useful for objects
whose string representation is already valid as SQL representation.</p>
<dl class="method">
<dt id="psycopg2.extensions.AsIs.getquoted">
<tt class="descname">getquoted</tt><big>(</big><big>)</big><a class="headerlink" href="#psycopg2.extensions.AsIs.getquoted" title="Permalink to this definition"></a></dt>
<dd><p>Return the <tt class="xref py py-obj docutils literal"><span class="pre">str()</span></tt> conversion of the wrapped object.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">AsIs</span><span class="p">(</span><span class="mi">42</span><span class="p">)</span><span class="o">.</span><span class="n">getquoted</span><span class="p">()</span>
<span class="go">&#39;42&#39;</span>
</pre></div>
</div>
</dd></dl>

</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.QuotedString">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">QuotedString</tt><big>(</big><em>str</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.QuotedString" title="Permalink to this definition"></a></dt>
<dd><p>Adapter conform to the <a class="reference internal" href="#psycopg2.extensions.ISQLQuote" title="psycopg2.extensions.ISQLQuote"><tt class="xref py py-obj docutils literal"><span class="pre">ISQLQuote</span></tt></a> protocol for string-like
objects.</p>
<dl class="method">
<dt id="psycopg2.extensions.QuotedString.getquoted">
<tt class="descname">getquoted</tt><big>(</big><big>)</big><a class="headerlink" href="#psycopg2.extensions.QuotedString.getquoted" title="Permalink to this definition"></a></dt>
<dd><p>Return the string enclosed in single quotes.  Any single quote
appearing in the the string is escaped by doubling it according to SQL
string constants syntax.  Backslashes are escaped too.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">QuotedString</span><span class="p">(</span><span class="s">r&quot;O&#39;Reilly&quot;</span><span class="p">)</span><span class="o">.</span><span class="n">getquoted</span><span class="p">()</span>
<span class="go">&quot;&#39;O&#39;&#39;Reilly&#39;&quot;</span>
</pre></div>
</div>
</dd></dl>

</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.Binary">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">Binary</tt><big>(</big><em>str</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.Binary" title="Permalink to this definition"></a></dt>
<dd><p>Adapter conform to the <a class="reference internal" href="#psycopg2.extensions.ISQLQuote" title="psycopg2.extensions.ISQLQuote"><tt class="xref py py-obj docutils literal"><span class="pre">ISQLQuote</span></tt></a> protocol for binary objects.</p>
<dl class="method">
<dt id="psycopg2.extensions.Binary.getquoted">
<tt class="descname">getquoted</tt><big>(</big><big>)</big><a class="headerlink" href="#psycopg2.extensions.Binary.getquoted" title="Permalink to this definition"></a></dt>
<dd><p>Return the string enclosed in single quotes.  It performs the same
escaping of the <a class="reference internal" href="#psycopg2.extensions.QuotedString" title="psycopg2.extensions.QuotedString"><tt class="xref py py-obj docutils literal"><span class="pre">QuotedString</span></tt></a> adapter, plus it knows how to
escape non-printable chars.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">Binary</span><span class="p">(</span><span class="s">&quot;</span><span class="se">\x00\x08\x0F</span><span class="s">&quot;</span><span class="p">)</span><span class="o">.</span><span class="n">getquoted</span><span class="p">()</span>
<span class="go">&quot;&#39;\\\\000\\\\010\\\\017&#39;&quot;</span>
</pre></div>
</div>
</dd></dl>

<div class="versionchanged">
<p><span class="versionmodified">Changed in version 2.0.14: </span>previously the adapter was not exposed by the <tt class="xref py py-obj docutils literal"><span class="pre">extensions</span></tt>
module. In older versions it can be imported from the implementation
module <tt class="xref py py-obj docutils literal"><span class="pre">psycopg2._psycopg</span></tt>.</p>
</div>
</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.Boolean">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">Boolean</tt><a class="headerlink" href="#psycopg2.extensions.Boolean" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.Float">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">Float</tt><a class="headerlink" href="#psycopg2.extensions.Float" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.SQL_IN">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">SQL_IN</tt><a class="headerlink" href="#psycopg2.extensions.SQL_IN" title="Permalink to this definition"></a></dt>
<dd><p>Specialized adapters for builtin objects.</p>
</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.DateFromPy">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">DateFromPy</tt><a class="headerlink" href="#psycopg2.extensions.DateFromPy" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.TimeFromPy">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TimeFromPy</tt><a class="headerlink" href="#psycopg2.extensions.TimeFromPy" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.TimestampFromPy">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TimestampFromPy</tt><a class="headerlink" href="#psycopg2.extensions.TimestampFromPy" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.IntervalFromPy">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">IntervalFromPy</tt><a class="headerlink" href="#psycopg2.extensions.IntervalFromPy" title="Permalink to this definition"></a></dt>
<dd><p>Specialized adapters for Python datetime objects.</p>
</dd></dl>

<dl class="class">
<dt id="psycopg2.extensions.DateFromMx">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">DateFromMx</tt><a class="headerlink" href="#psycopg2.extensions.DateFromMx" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.TimeFromMx">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TimeFromMx</tt><a class="headerlink" href="#psycopg2.extensions.TimeFromMx" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.TimestampFromMx">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TimestampFromMx</tt><a class="headerlink" href="#psycopg2.extensions.TimestampFromMx" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.IntervalFromMx">
<em class="property">class </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">IntervalFromMx</tt><a class="headerlink" href="#psycopg2.extensions.IntervalFromMx" title="Permalink to this definition"></a></dt>
<dd><p>Specialized adapters for <a class="reference external" href="http://www.egenix.com/products/python/mxBase/mxDateTime/">mx.DateTime</a> objects.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.adapters">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">adapters</tt><a class="headerlink" href="#psycopg2.extensions.adapters" title="Permalink to this definition"></a></dt>
<dd><p>Dictionary of the currently registered object adapters.  Use
<a class="reference internal" href="#psycopg2.extensions.register_adapter" title="psycopg2.extensions.register_adapter"><tt class="xref py py-obj docutils literal"><span class="pre">register_adapter()</span></tt></a> to add an adapter for a new type.</p>
</dd></dl>

</div>
<div class="section" id="database-types-casting-functions">
<h2>Database types casting functions<a class="headerlink" href="#database-types-casting-functions" title="Permalink to this headline"></a></h2>
<p>These functions are used to manipulate type casters to convert from PostgreSQL
types to Python objects.  See <a class="reference internal" href="advanced.html#type-casting-from-sql-to-python"><em>Type casting of SQL types into Python objects</em></a> for
details.</p>
<dl class="function">
<dt id="psycopg2.extensions.new_type">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">new_type</tt><big>(</big><em>oids</em>, <em>name</em>, <em>adapter</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.new_type" title="Permalink to this definition"></a></dt>
<dd><p>Create a new type caster to convert from a PostgreSQL type to a Python
object.  The object created must be registered using
<a class="reference internal" href="#psycopg2.extensions.register_type" title="psycopg2.extensions.register_type"><tt class="xref py py-obj docutils literal"><span class="pre">register_type()</span></tt></a> to be used.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>oids</strong> &#8211; tuple of OIDs of the PostgreSQL type to convert.</li>
<li><strong>name</strong> &#8211; the name of the new type adapter.</li>
<li><strong>adapter</strong> &#8211; the adaptation function.</li>
</ul>
</td>
</tr>
</tbody>
</table>
<p>The object OID can be read from the <a class="reference internal" href="cursor.html#cursor.description" title="cursor.description"><tt class="xref py py-obj docutils literal"><span class="pre">cursor.description</span></tt></a> attribute
or by querying from the PostgreSQL catalog.</p>
<p><em>adapter</em> should have signature <tt class="samp docutils literal"><span class="pre">fun(</span><em><span class="pre">value</span></em><span class="pre">,</span> <em><span class="pre">cur</span></em><span class="pre">)</span></tt> where
<em>value</em> is the string representation returned by PostgreSQL and
<em>cur</em> is the cursor from which data are read. In case of
<tt class="sql docutils literal"><span class="pre">NULL</span></tt>, <em>value</em> will be <tt class="xref py py-obj docutils literal"><span class="pre">None</span></tt>. The adapter should return the
converted object.</p>
<p>See <a class="reference internal" href="advanced.html#type-casting-from-sql-to-python"><em>Type casting of SQL types into Python objects</em></a> for an usage example.</p>
</dd></dl>

<dl class="function">
<dt id="psycopg2.extensions.new_array_type">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">new_array_type</tt><big>(</big><em>oids</em>, <em>name</em>, <em>base_caster</em><big>)</big><a class="headerlink" href="#psycopg2.extensions.new_array_type" title="Permalink to this definition"></a></dt>
<dd><p>Create a new type caster to convert from a PostgreSQL array type to a list
of Python object.  The object created must be registered using
<a class="reference internal" href="#psycopg2.extensions.register_type" title="psycopg2.extensions.register_type"><tt class="xref py py-obj docutils literal"><span class="pre">register_type()</span></tt></a> to be used.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>oids</strong> &#8211; tuple of OIDs of the PostgreSQL type to convert. It should
probably be the oid of the array type (e.g. the <tt class="docutils literal"><span class="pre">typarray</span></tt> field in
the <tt class="docutils literal"><span class="pre">pg_type</span></tt> table.</li>
<li><strong>name</strong> &#8211; the name of the new type adapter.</li>
<li><strong>base_caster</strong> &#8211; a Psycopg typecaster, e.g. created using the
<a class="reference internal" href="#psycopg2.extensions.new_type" title="psycopg2.extensions.new_type"><tt class="xref py py-obj docutils literal"><span class="pre">new_type()</span></tt></a> function. The caster should be able to parse a single
item of the desired type.</li>
</ul>
</td>
</tr>
</tbody>
</table>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.4.3.</span></p>
</div>
<div class="admonition note" id="cast-array-unknown">
<p class="first admonition-title">Note</p>
<p>The function can be used to create a generic array typecaster,
returning a list of strings: just use the <a class="reference internal" href="module.html#psycopg2.STRING" title="psycopg2.STRING"><tt class="xref py py-obj docutils literal"><span class="pre">STRING</span></tt></a> as base
typecaster. For instance, if you want to receive from the database an
array of <tt class="sql docutils literal"><span class="pre">macaddr</span></tt>, each address represented by string, you can
use:</p>
<div class="last highlight-python"><div class="highlight"><pre><span class="n">psycopg2</span><span class="o">.</span><span class="n">extensions</span><span class="o">.</span><span class="n">register_type</span><span class="p">(</span>
    <span class="n">psycopg2</span><span class="o">.</span><span class="n">extensions</span><span class="o">.</span><span class="n">new_array_type</span><span class="p">(</span>
        <span class="p">(</span><span class="mi">1040</span><span class="p">,),</span> <span class="s">&#39;MACADDR[]&#39;</span><span class="p">,</span> <span class="n">psycopg2</span><span class="o">.</span><span class="n">STRING</span><span class="p">))</span>
</pre></div>
</div>
</div>
</dd></dl>

<dl class="function">
<dt id="psycopg2.extensions.register_type">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">register_type</tt><big>(</big><em>obj</em><span class="optional">[</span>, <em>scope</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#psycopg2.extensions.register_type" title="Permalink to this definition"></a></dt>
<dd><p>Register a type caster created using <a class="reference internal" href="#psycopg2.extensions.new_type" title="psycopg2.extensions.new_type"><tt class="xref py py-obj docutils literal"><span class="pre">new_type()</span></tt></a>.</p>
<p>If <em>scope</em> is specified, it should be a <a class="reference internal" href="connection.html#connection" title="connection"><tt class="xref py py-obj docutils literal"><span class="pre">connection</span></tt></a> or a
<a class="reference internal" href="cursor.html#cursor" title="cursor"><tt class="xref py py-obj docutils literal"><span class="pre">cursor</span></tt></a>: the type caster will be effective only limited to the
specified object.  Otherwise it will be globally registered.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.string_types">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">string_types</tt><a class="headerlink" href="#psycopg2.extensions.string_types" title="Permalink to this definition"></a></dt>
<dd><p>The global register of type casters.</p>
</dd></dl>

<span class="target" id="index-2"></span><dl class="data">
<dt id="psycopg2.extensions.encodings">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">encodings</tt><a class="headerlink" href="#psycopg2.extensions.encodings" title="Permalink to this definition"></a></dt>
<dd><p>Mapping from <a class="reference external" href="http://www.postgresql.org/docs/current/static/multibyte.html">PostgreSQL encoding</a> names to <a class="reference external" href="http://docs.python.org/library/codecs.html#standard-encodings">Python codec</a> names.
Used by Psycopg when adapting or casting unicode strings. See
<a class="reference internal" href="usage.html#unicode-handling"><em>Unicode handling</em></a>.</p>
</dd></dl>

</div>
<div class="section" id="additional-exceptions">
<span id="index-3"></span><h2>Additional exceptions<a class="headerlink" href="#additional-exceptions" title="Permalink to this headline"></a></h2>
<p>The module exports a few exceptions in addition to the <a class="reference internal" href="module.html#dbapi-exceptions"><em>standard ones</em></a> defined by the <a class="reference external" href="http://www.python.org/dev/peps/pep-0249/">DB API 2.0</a>.</p>
<dl class="exception">
<dt id="psycopg2.extensions.QueryCanceledError">
<em class="property">exception </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">QueryCanceledError</tt><a class="headerlink" href="#psycopg2.extensions.QueryCanceledError" title="Permalink to this definition"></a></dt>
<dd><p>(subclasses <a class="reference internal" href="module.html#psycopg2.OperationalError" title="psycopg2.OperationalError"><tt class="xref py py-obj docutils literal"><span class="pre">OperationalError</span></tt></a>)</p>
<p>Error related to SQL query cancellation.  It can be trapped specifically to
detect a timeout.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.0.7.</span></p>
</div>
</dd></dl>

<dl class="exception">
<dt id="psycopg2.extensions.TransactionRollbackError">
<em class="property">exception </em><tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TransactionRollbackError</tt><a class="headerlink" href="#psycopg2.extensions.TransactionRollbackError" title="Permalink to this definition"></a></dt>
<dd><p>(subclasses <a class="reference internal" href="module.html#psycopg2.OperationalError" title="psycopg2.OperationalError"><tt class="xref py py-obj docutils literal"><span class="pre">OperationalError</span></tt></a>)</p>
<p>Error causing transaction rollback (deadlocks, serialisation failures,
etc).  It can be trapped specifically to detect a deadlock.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.0.7.</span></p>
</div>
</dd></dl>

</div>
<div class="section" id="isolation-level-constants">
<span id="index-4"></span><span id="id3"></span><h2>Isolation level constants<a class="headerlink" href="#isolation-level-constants" title="Permalink to this headline"></a></h2>
<p>Psycopg2 <a class="reference internal" href="connection.html#connection" title="connection"><tt class="xref py py-obj docutils literal"><span class="pre">connection</span></tt></a> objects hold informations about the PostgreSQL
<a class="reference external" href="http://www.postgresql.org/docs/current/static/transaction-iso.html">transaction isolation level</a>.  The current transaction level can be read
from the <a class="reference internal" href="connection.html#connection.isolation_level" title="connection.isolation_level"><tt class="xref py py-obj docutils literal"><span class="pre">isolation_level</span></tt></a> attribute.  The default isolation
level is <tt class="sql docutils literal"><span class="pre">READ</span> <span class="pre">COMMITTED</span></tt>.  A different isolation level con be set
through the <a class="reference internal" href="connection.html#connection.set_isolation_level" title="connection.set_isolation_level"><tt class="xref py py-obj docutils literal"><span class="pre">set_isolation_level()</span></tt></a> method.  The level can be
set to one of the following constants:</p>
<dl class="data">
<dt id="psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">ISOLATION_LEVEL_AUTOCOMMIT</tt><a class="headerlink" href="#psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT" title="Permalink to this definition"></a></dt>
<dd><p>No transaction is started when command are issued and no
<a class="reference internal" href="connection.html#connection.commit" title="connection.commit"><tt class="xref py py-obj docutils literal"><span class="pre">commit()</span></tt></a> or <a class="reference internal" href="connection.html#connection.rollback" title="connection.rollback"><tt class="xref py py-obj docutils literal"><span class="pre">rollback()</span></tt></a> is required.
Some PostgreSQL command such as <tt class="sql docutils literal"><span class="pre">CREATE</span> <span class="pre">DATABASE</span></tt> or <tt class="sql docutils literal"><span class="pre">VACUUM</span></tt>
can&#8217;t run into a transaction: to run such command use:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">conn</span><span class="o">.</span><span class="n">set_isolation_level</span><span class="p">(</span><span class="n">ISOLATION_LEVEL_AUTOCOMMIT</span><span class="p">)</span>
</pre></div>
</div>
<p>See also <a class="reference internal" href="usage.html#transactions-control"><em>Transactions control</em></a>.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.ISOLATION_LEVEL_READ_UNCOMMITTED">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">ISOLATION_LEVEL_READ_UNCOMMITTED</tt><a class="headerlink" href="#psycopg2.extensions.ISOLATION_LEVEL_READ_UNCOMMITTED" title="Permalink to this definition"></a></dt>
<dd><p>The <tt class="sql docutils literal"><span class="pre">READ</span> <span class="pre">UNCOMMITTED</span></tt> isolation level is defined in the SQL standard
but not available in the <abbr title="Multiversion concurrency control">MVCC</abbr> model of PostgreSQL: it is replaced by the
stricter <tt class="sql docutils literal"><span class="pre">READ</span> <span class="pre">COMMITTED</span></tt>.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.ISOLATION_LEVEL_READ_COMMITTED">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">ISOLATION_LEVEL_READ_COMMITTED</tt><a class="headerlink" href="#psycopg2.extensions.ISOLATION_LEVEL_READ_COMMITTED" title="Permalink to this definition"></a></dt>
<dd><p>This is usually the the default PostgreSQL value, but a different default
may be set in the database configuration.</p>
<p>A new transaction is started at the first <a class="reference internal" href="cursor.html#cursor.execute" title="cursor.execute"><tt class="xref py py-obj docutils literal"><span class="pre">execute()</span></tt></a> command on a
cursor and at each new <tt class="xref py py-obj docutils literal"><span class="pre">execute()</span></tt> after a <a class="reference internal" href="connection.html#connection.commit" title="connection.commit"><tt class="xref py py-obj docutils literal"><span class="pre">commit()</span></tt></a> or a
<a class="reference internal" href="connection.html#connection.rollback" title="connection.rollback"><tt class="xref py py-obj docutils literal"><span class="pre">rollback()</span></tt></a>.  The transaction runs in the PostgreSQL
<tt class="sql docutils literal"><span class="pre">READ</span> <span class="pre">COMMITTED</span></tt> isolation level: a <tt class="sql docutils literal"><span class="pre">SELECT</span></tt> query sees only
data committed before the query began; it never sees either uncommitted
data or changes committed during query execution by concurrent
transactions.</p>
<div class="admonition seealso">
<p class="first admonition-title">See also</p>
<p class="last"><a class="reference external" href="http://www.postgresql.org/docs/current/static/transaction-iso.html#XACT-READ-COMMITTED">Read Committed Isolation Level</a> in PostgreSQL
documentation.</p>
</div>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.ISOLATION_LEVEL_REPEATABLE_READ">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">ISOLATION_LEVEL_REPEATABLE_READ</tt><a class="headerlink" href="#psycopg2.extensions.ISOLATION_LEVEL_REPEATABLE_READ" title="Permalink to this definition"></a></dt>
<dd><p>As in <tt class="xref py py-obj docutils literal"><span class="pre">ISOLATION_LEVEL_READ_COMMITTED</span></tt>, a new transaction is started at
the first <a class="reference internal" href="cursor.html#cursor.execute" title="cursor.execute"><tt class="xref py py-obj docutils literal"><span class="pre">execute()</span></tt></a> command.  Transactions run at a
<tt class="sql docutils literal"><span class="pre">REPEATABLE</span> <span class="pre">READ</span></tt> isolation level: all the queries in a transaction
see a snapshot as of the start of the transaction, not as of the start of
the current query within the transaction.  However applications using this
level must be prepared to retry transactions due to serialization
failures.</p>
<p>While this level provides a guarantee that each transaction sees a
completely stable view of the database, this view will not necessarily
always be consistent with some serial (one at a time) execution of
concurrent transactions of the same level.</p>
<div class="versionchanged">
<p><span class="versionmodified">Changed in version 2.4.2: </span>The value was an alias for <tt class="xref py py-obj docutils literal"><span class="pre">ISOLATION_LEVEL_SERIALIZABLE</span></tt> before. The
two levels are distinct since PostgreSQL 9.1</p>
</div>
<div class="admonition seealso">
<p class="first admonition-title">See also</p>
<p class="last"><a class="reference external" href="http://www.postgresql.org/docs/current/static/transaction-iso.html#XACT-REPEATABLE-READ">Repeatable Read Isolation Level</a> in PostgreSQL
documentation.</p>
</div>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.ISOLATION_LEVEL_SERIALIZABLE">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">ISOLATION_LEVEL_SERIALIZABLE</tt><a class="headerlink" href="#psycopg2.extensions.ISOLATION_LEVEL_SERIALIZABLE" title="Permalink to this definition"></a></dt>
<dd><p>As in <tt class="xref py py-obj docutils literal"><span class="pre">ISOLATION_LEVEL_READ_COMMITTED</span></tt>, a new transaction is started at
the first <a class="reference internal" href="cursor.html#cursor.execute" title="cursor.execute"><tt class="xref py py-obj docutils literal"><span class="pre">execute()</span></tt></a> command.  Transactions run at a
<tt class="sql docutils literal"><span class="pre">SERIALIZABLE</span></tt> isolation level. This is the strictest transactions
isolation level, equivalent to having the transactions executed serially
rather than concurrently. However applications using this level must be
prepared to retry reansactions due to serialization failures.</p>
<p>Starting from PostgreSQL 9.1, this mode monitors for conditions which
could make execution of a concurrent set of serializable transactions
behave in a manner inconsistent with all possible serial (one at a time)
executions of those transaction. In previous version the behaviour was the
same of the <tt class="sql docutils literal"><span class="pre">REPEATABLE</span> <span class="pre">READ</span></tt> isolation level.</p>
<div class="admonition seealso">
<p class="first admonition-title">See also</p>
<p class="last"><a class="reference external" href="http://www.postgresql.org/docs/current/static/transaction-iso.html#XACT-SERIALIZABLE">Serializable Isolation Level</a> in PostgreSQL documentation.</p>
</div>
</dd></dl>

</div>
<div class="section" id="transaction-status-constants">
<span id="index-5"></span><span id="id7"></span><h2>Transaction status constants<a class="headerlink" href="#transaction-status-constants" title="Permalink to this headline"></a></h2>
<p>These values represent the possible status of a transaction: the current value
can be read using the <a class="reference internal" href="connection.html#connection.get_transaction_status" title="connection.get_transaction_status"><tt class="xref py py-obj docutils literal"><span class="pre">connection.get_transaction_status()</span></tt></a> method.</p>
<dl class="data">
<dt id="psycopg2.extensions.TRANSACTION_STATUS_IDLE">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TRANSACTION_STATUS_IDLE</tt><a class="headerlink" href="#psycopg2.extensions.TRANSACTION_STATUS_IDLE" title="Permalink to this definition"></a></dt>
<dd><p>The session is idle and there is no current transaction.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.TRANSACTION_STATUS_ACTIVE">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TRANSACTION_STATUS_ACTIVE</tt><a class="headerlink" href="#psycopg2.extensions.TRANSACTION_STATUS_ACTIVE" title="Permalink to this definition"></a></dt>
<dd><p>A command is currently in progress.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.TRANSACTION_STATUS_INTRANS">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TRANSACTION_STATUS_INTRANS</tt><a class="headerlink" href="#psycopg2.extensions.TRANSACTION_STATUS_INTRANS" title="Permalink to this definition"></a></dt>
<dd><p>The session is idle in a valid transaction block.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.TRANSACTION_STATUS_INERROR">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TRANSACTION_STATUS_INERROR</tt><a class="headerlink" href="#psycopg2.extensions.TRANSACTION_STATUS_INERROR" title="Permalink to this definition"></a></dt>
<dd><p>The session is idle in a failed transaction block.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.TRANSACTION_STATUS_UNKNOWN">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TRANSACTION_STATUS_UNKNOWN</tt><a class="headerlink" href="#psycopg2.extensions.TRANSACTION_STATUS_UNKNOWN" title="Permalink to this definition"></a></dt>
<dd><p>Reported if the connection with the server is bad.</p>
</dd></dl>

</div>
<div class="section" id="connection-status-constants">
<span id="index-6"></span><span id="id8"></span><h2>Connection status constants<a class="headerlink" href="#connection-status-constants" title="Permalink to this headline"></a></h2>
<p>These values represent the possible status of a connection: the current value
can be read from the <a class="reference internal" href="connection.html#connection.status" title="connection.status"><tt class="xref py py-obj docutils literal"><span class="pre">status</span></tt></a> attribute.</p>
<p>It is possible to find the connection in other status than the one shown below.
Those are the only states in which a working connection is expected to be found
during the execution of regular Python client code: other states are for
internal usage and Python code should not rely on them.</p>
<dl class="data">
<dt id="psycopg2.extensions.STATUS_READY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">STATUS_READY</tt><a class="headerlink" href="#psycopg2.extensions.STATUS_READY" title="Permalink to this definition"></a></dt>
<dd><p>Connection established. No transaction in progress.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.STATUS_BEGIN">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">STATUS_BEGIN</tt><a class="headerlink" href="#psycopg2.extensions.STATUS_BEGIN" title="Permalink to this definition"></a></dt>
<dd><p>Connection established. A transaction is currently in progress.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.STATUS_IN_TRANSACTION">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">STATUS_IN_TRANSACTION</tt><a class="headerlink" href="#psycopg2.extensions.STATUS_IN_TRANSACTION" title="Permalink to this definition"></a></dt>
<dd><p>An alias for <a class="reference internal" href="#psycopg2.extensions.STATUS_BEGIN" title="psycopg2.extensions.STATUS_BEGIN"><tt class="xref py py-obj docutils literal"><span class="pre">STATUS_BEGIN</span></tt></a></p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.STATUS_PREPARED">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">STATUS_PREPARED</tt><a class="headerlink" href="#psycopg2.extensions.STATUS_PREPARED" title="Permalink to this definition"></a></dt>
<dd><p>The connection has been prepared for the second phase in a <a class="reference internal" href="usage.html#tpc"><em>two-phase
commit</em></a> transaction. The connection can&#8217;t be used to send commands
to the database until the transaction is finished with
<a class="reference internal" href="connection.html#connection.tpc_commit" title="connection.tpc_commit"><tt class="xref py py-obj docutils literal"><span class="pre">tpc_commit()</span></tt></a> or <a class="reference internal" href="connection.html#connection.tpc_rollback" title="connection.tpc_rollback"><tt class="xref py py-obj docutils literal"><span class="pre">tpc_rollback()</span></tt></a>.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.3.</span></p>
</div>
</dd></dl>

</div>
<div class="section" id="poll-constants">
<span id="index-7"></span><span id="id9"></span><h2>Poll constants<a class="headerlink" href="#poll-constants" title="Permalink to this headline"></a></h2>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.2.0.</span></p>
</div>
<p>These values can be returned by <a class="reference internal" href="connection.html#connection.poll" title="connection.poll"><tt class="xref py py-obj docutils literal"><span class="pre">connection.poll()</span></tt></a> during asynchronous
connection and communication.  They match the values in the libpq enum
<tt class="xref py py-obj docutils literal"><span class="pre">PostgresPollingStatusType</span></tt>.  See <a class="reference internal" href="advanced.html#async-support"><em>Asynchronous support</em></a> and
<a class="reference internal" href="advanced.html#green-support"><em>Support to coroutine libraries</em></a>.</p>
<dl class="data">
<dt id="psycopg2.extensions.POLL_OK">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">POLL_OK</tt><a class="headerlink" href="#psycopg2.extensions.POLL_OK" title="Permalink to this definition"></a></dt>
<dd><p>The data being read is available, or the file descriptor is ready for
writing: reading or writing will not block.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.POLL_READ">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">POLL_READ</tt><a class="headerlink" href="#psycopg2.extensions.POLL_READ" title="Permalink to this definition"></a></dt>
<dd><p>Some data is being read from the backend, but it is not available yet on
the client and reading would block.  Upon receiving this value, the client
should wait for the connection file descriptor to be ready <em>for reading</em>.
For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">select</span><span class="o">.</span><span class="n">select</span><span class="p">([</span><span class="n">conn</span><span class="o">.</span><span class="n">fileno</span><span class="p">()],</span> <span class="p">[],</span> <span class="p">[])</span>
</pre></div>
</div>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.POLL_WRITE">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">POLL_WRITE</tt><a class="headerlink" href="#psycopg2.extensions.POLL_WRITE" title="Permalink to this definition"></a></dt>
<dd><p>Some data is being sent to the backend but the connection file descriptor
can&#8217;t currently accept new data.  Upon receiving this value, the client
should wait for the connection file descriptor to be ready <em>for writing</em>.
For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">select</span><span class="o">.</span><span class="n">select</span><span class="p">([],</span> <span class="p">[</span><span class="n">conn</span><span class="o">.</span><span class="n">fileno</span><span class="p">()],</span> <span class="p">[])</span>
</pre></div>
</div>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.POLL_ERROR">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">POLL_ERROR</tt><a class="headerlink" href="#psycopg2.extensions.POLL_ERROR" title="Permalink to this definition"></a></dt>
<dd><p>There was a problem during connection polling. This value should actually
never be returned: in case of poll error usually an exception containing
the relevant details is raised.</p>
</dd></dl>

</div>
<div class="section" id="additional-database-types">
<h2>Additional database types<a class="headerlink" href="#additional-database-types" title="Permalink to this headline"></a></h2>
<p>The <tt class="xref py py-obj docutils literal"><span class="pre">extensions</span></tt> module includes typecasters for many standard
PostgreSQL types.  These objects allow the conversion of returned data into
Python objects.  All the typecasters are automatically registered, except
<a class="reference internal" href="#psycopg2.extensions.UNICODE" title="psycopg2.extensions.UNICODE"><tt class="xref py py-obj docutils literal"><span class="pre">UNICODE</span></tt></a> and <a class="reference internal" href="#psycopg2.extensions.UNICODEARRAY" title="psycopg2.extensions.UNICODEARRAY"><tt class="xref py py-obj docutils literal"><span class="pre">UNICODEARRAY</span></tt></a>: you can register them using
<a class="reference internal" href="#psycopg2.extensions.register_type" title="psycopg2.extensions.register_type"><tt class="xref py py-obj docutils literal"><span class="pre">register_type()</span></tt></a> in order to receive Unicode objects instead of strings
from the database.  See <a class="reference internal" href="usage.html#unicode-handling"><em>Unicode handling</em></a> for details.</p>
<dl class="data">
<dt id="psycopg2.extensions.BOOLEAN">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">BOOLEAN</tt><a class="headerlink" href="#psycopg2.extensions.BOOLEAN" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.DATE">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">DATE</tt><a class="headerlink" href="#psycopg2.extensions.DATE" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.DECIMAL">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">DECIMAL</tt><a class="headerlink" href="#psycopg2.extensions.DECIMAL" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.FLOAT">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">FLOAT</tt><a class="headerlink" href="#psycopg2.extensions.FLOAT" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.INTEGER">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">INTEGER</tt><a class="headerlink" href="#psycopg2.extensions.INTEGER" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.INTERVAL">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">INTERVAL</tt><a class="headerlink" href="#psycopg2.extensions.INTERVAL" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.LONGINTEGER">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">LONGINTEGER</tt><a class="headerlink" href="#psycopg2.extensions.LONGINTEGER" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.TIME">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TIME</tt><a class="headerlink" href="#psycopg2.extensions.TIME" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.UNICODE">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">UNICODE</tt><a class="headerlink" href="#psycopg2.extensions.UNICODE" title="Permalink to this definition"></a></dt>
<dd><p>Typecasters for basic types. Note that a few other ones (<a class="reference internal" href="module.html#psycopg2.BINARY" title="psycopg2.BINARY"><tt class="xref py py-obj docutils literal"><span class="pre">BINARY</span></tt></a>,
<a class="reference internal" href="module.html#psycopg2.DATETIME" title="psycopg2.DATETIME"><tt class="xref py py-obj docutils literal"><span class="pre">DATETIME</span></tt></a>, <a class="reference internal" href="module.html#psycopg2.NUMBER" title="psycopg2.NUMBER"><tt class="xref py py-obj docutils literal"><span class="pre">NUMBER</span></tt></a>, <a class="reference internal" href="module.html#psycopg2.ROWID" title="psycopg2.ROWID"><tt class="xref py py-obj docutils literal"><span class="pre">ROWID</span></tt></a>,
<a class="reference internal" href="module.html#psycopg2.STRING" title="psycopg2.STRING"><tt class="xref py py-obj docutils literal"><span class="pre">STRING</span></tt></a>) are exposed by the <a class="reference internal" href="module.html#module-psycopg2" title="psycopg2"><tt class="xref py py-obj docutils literal"><span class="pre">psycopg2</span></tt></a> module for <a class="reference external" href="http://www.python.org/dev/peps/pep-0249/">DB API 2.0</a>
compliance.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.BINARYARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">BINARYARRAY</tt><a class="headerlink" href="#psycopg2.extensions.BINARYARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.BOOLEANARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">BOOLEANARRAY</tt><a class="headerlink" href="#psycopg2.extensions.BOOLEANARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.DATEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">DATEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.DATEARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.DATETIMEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">DATETIMEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.DATETIMEARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.DECIMALARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">DECIMALARRAY</tt><a class="headerlink" href="#psycopg2.extensions.DECIMALARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.FLOATARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">FLOATARRAY</tt><a class="headerlink" href="#psycopg2.extensions.FLOATARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.INTEGERARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">INTEGERARRAY</tt><a class="headerlink" href="#psycopg2.extensions.INTEGERARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.INTERVALARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">INTERVALARRAY</tt><a class="headerlink" href="#psycopg2.extensions.INTERVALARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.LONGINTEGERARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">LONGINTEGERARRAY</tt><a class="headerlink" href="#psycopg2.extensions.LONGINTEGERARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.ROWIDARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">ROWIDARRAY</tt><a class="headerlink" href="#psycopg2.extensions.ROWIDARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.STRINGARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">STRINGARRAY</tt><a class="headerlink" href="#psycopg2.extensions.STRINGARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.TIMEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">TIMEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.TIMEARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.UNICODEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">UNICODEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.UNICODEARRAY" title="Permalink to this definition"></a></dt>
<dd><p>Typecasters to convert arrays of sql types into Python lists.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.PYDATE">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">PYDATE</tt><a class="headerlink" href="#psycopg2.extensions.PYDATE" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.PYDATETIME">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">PYDATETIME</tt><a class="headerlink" href="#psycopg2.extensions.PYDATETIME" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.PYINTERVAL">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">PYINTERVAL</tt><a class="headerlink" href="#psycopg2.extensions.PYINTERVAL" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.PYTIME">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">PYTIME</tt><a class="headerlink" href="#psycopg2.extensions.PYTIME" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.PYDATEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">PYDATEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.PYDATEARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.PYDATETIMEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">PYDATETIMEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.PYDATETIMEARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.PYINTERVALARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">PYINTERVALARRAY</tt><a class="headerlink" href="#psycopg2.extensions.PYINTERVALARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.PYTIMEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">PYTIMEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.PYTIMEARRAY" title="Permalink to this definition"></a></dt>
<dd><p>Typecasters to convert time-related data types to Python <tt class="xref py py-obj docutils literal"><span class="pre">datetime</span></tt>
objects.</p>
</dd></dl>

<dl class="data">
<dt id="psycopg2.extensions.MXDATE">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">MXDATE</tt><a class="headerlink" href="#psycopg2.extensions.MXDATE" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.MXDATETIME">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">MXDATETIME</tt><a class="headerlink" href="#psycopg2.extensions.MXDATETIME" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.MXINTERVAL">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">MXINTERVAL</tt><a class="headerlink" href="#psycopg2.extensions.MXINTERVAL" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.MXTIME">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">MXTIME</tt><a class="headerlink" href="#psycopg2.extensions.MXTIME" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.MXDATEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">MXDATEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.MXDATEARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.MXDATETIMEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">MXDATETIMEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.MXDATETIMEARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.MXINTERVALARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">MXINTERVALARRAY</tt><a class="headerlink" href="#psycopg2.extensions.MXINTERVALARRAY" title="Permalink to this definition"></a></dt>
<dt id="psycopg2.extensions.MXTIMEARRAY">
<tt class="descclassname">psycopg2.extensions.</tt><tt class="descname">MXTIMEARRAY</tt><a class="headerlink" href="#psycopg2.extensions.MXTIMEARRAY" title="Permalink to this definition"></a></dt>
<dd><p>Typecasters to convert time-related data types to <a class="reference external" href="http://www.egenix.com/products/python/mxBase/mxDateTime/">mx.DateTime</a> objects.
Only available if Psycopg was compiled with <tt class="xref py py-obj docutils literal"><span class="pre">mx</span></tt> support.</p>
</dd></dl>

<div class="versionchanged">
<p><span class="versionmodified">Changed in version 2.2.0: </span>previously the <a class="reference internal" href="#psycopg2.extensions.DECIMAL" title="psycopg2.extensions.DECIMAL"><tt class="xref py py-obj docutils literal"><span class="pre">DECIMAL</span></tt></a> typecaster and the specific time-related
typecasters (<tt class="xref py py-obj docutils literal"><span class="pre">PY*</span></tt> and <tt class="xref py py-obj docutils literal"><span class="pre">MX*</span></tt>) were not exposed by the <tt class="xref py py-obj docutils literal"><span class="pre">extensions</span></tt>
module. In older versions they can be imported from the implementation
module <tt class="xref py py-obj docutils literal"><span class="pre">psycopg2._psycopg</span></tt>.</p>
</div>
</div>
</div>


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  <h3><a href="index.html">Table Of Contents</a></h3>
  <ul>
<li><a class="reference internal" href="#"><tt class="docutils literal"><span class="pre">psycopg2.extensions</span></tt> &#8211; Extensions to the DB API</a><ul>
<li><a class="reference internal" href="#sql-adaptation-protocol-objects">SQL adaptation protocol objects</a></li>
<li><a class="reference internal" href="#database-types-casting-functions">Database types casting functions</a></li>
<li><a class="reference internal" href="#additional-exceptions">Additional exceptions</a></li>
<li><a class="reference internal" href="#isolation-level-constants">Isolation level constants</a></li>
<li><a class="reference internal" href="#transaction-status-constants">Transaction status constants</a></li>
<li><a class="reference internal" href="#connection-status-constants">Connection status constants</a></li>
<li><a class="reference internal" href="#poll-constants">Poll constants</a></li>
<li><a class="reference internal" href="#additional-database-types">Additional database types</a></li>
</ul>
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</ul>

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