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pgloader/docs/_build/html/ref/transforms.html
Dimitri Fontaine 25c79dfebc Switch the documentation to using Sphinx. 
The website is moving to pgloader.org and readthedocs.io is going to be
integrated. Let's see what happens. The docs build fine locally with the
sphinx tools and the docs/Makefile.

Having separate files for the documentation should help ease the maintenance
and add new topics, such as support for Common Lisp Hackers level docs,
which are currently missing.
2017-12-21 17:45:09 +01:00

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<title>Transformation Functions &#8212; pgloader 3.4.1 documentation</title>
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<div class="section" id="transformation-functions">
<h1>Transformation Functions<a class="headerlink" href="#transformation-functions" title="Permalink to this headline"></a></h1>
<p>Some data types are implemented in a different enough way that a
transformation function is necessary. This function must be written in
<cite>Common lisp</cite> and is searched in the <cite>pgloader.transforms</cite> package.</p>
<p>Some default transformation function are provided with pgloader, and you can
use the <cite>–load</cite> command line option to load and compile your own lisp file
into pgloader at runtime. For your functions to be found, remember to begin
your lisp file with the following form:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">(</span><span class="ow">in</span><span class="o">-</span><span class="n">package</span> <span class="c1">#:pgloader.transforms)</span>
</pre></div>
</div>
<p>The provided transformation functions are:</p>
<blockquote>
<div><ul>
<li><p class="first"><em>zero-dates-to-null</em></p>
<p>When the input date is all zeroes, return <cite>nil</cite>, which gets loaded as a
PostgreSQL <cite>NULL</cite> value.</p>
</li>
<li><p class="first"><em>date-with-no-separator</em></p>
<p>Applies <em>zero-dates-to-null</em> then transform the given date into a format
that PostgreSQL will actually process:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">In</span><span class="p">:</span> <span class="s2">&quot;20041002152952&quot;</span>
<span class="n">Out</span><span class="p">:</span> <span class="s2">&quot;2004-10-02 15:29:52&quot;</span>
</pre></div>
</div>
</li>
<li><p class="first"><em>time-with-no-separator</em></p>
<p>Transform the given time into a format that PostgreSQL will actually
process:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">In</span><span class="p">:</span> <span class="s2">&quot;08231560&quot;</span>
<span class="n">Out</span><span class="p">:</span> <span class="s2">&quot;08:23:15.60&quot;</span>
</pre></div>
</div>
</li>
<li><p class="first"><em>tinyint-to-boolean</em></p>
<p>As MySQL lacks a proper boolean type, <em>tinyint</em> is often used to
implement that. This function transforms <cite>0</cite> to <cite>‘false’</cite> and anything
else to <cite>‘true</cite>’.</p>
</li>
<li><p class="first"><em>bits-to-boolean</em></p>
<p>As MySQL lacks a proper boolean type, <em>BIT</em> is often used to implement
that. This function transforms 1-bit bit vectors from <cite>0</cite> to <cite>f</cite> and any
other value to <cite>t</cite>..</p>
</li>
<li><p class="first"><em>int-to-ip</em></p>
<p>Convert an integer into a dotted representation of an ip4.</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">In</span><span class="p">:</span> <span class="mi">18435761</span>
<span class="n">Out</span><span class="p">:</span> <span class="s2">&quot;1.25.78.177&quot;</span>
</pre></div>
</div>
</li>
<li><p class="first"><em>ip-range</em></p>
<p>Converts a couple of integers given as strings into a range of ip4.</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">In</span><span class="p">:</span> <span class="s2">&quot;16825344&quot;</span> <span class="s2">&quot;16825599&quot;</span>
<span class="n">Out</span><span class="p">:</span> <span class="s2">&quot;1.0.188.0-1.0.188.255&quot;</span>
</pre></div>
</div>
</li>
<li><p class="first"><em>convert-mysql-point</em></p>
<p>Converts from the <cite>astext</cite> representation of points in MySQL to the
PostgreSQL representation.</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">In</span><span class="p">:</span> <span class="s2">&quot;POINT(48.5513589 7.6926827)&quot;</span>
<span class="n">Out</span><span class="p">:</span> <span class="s2">&quot;(48.5513589,7.6926827)&quot;</span>
</pre></div>
</div>
</li>
<li><p class="first"><em>integer-to-string</em></p>
<p>Converts a integer string or a Common Lisp integer into a string
suitable for a PostgreSQL integer. Takes care of quoted integers.</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">In</span><span class="p">:</span> <span class="s2">&quot;</span><span class="se">\&quot;</span><span class="s2">0</span><span class="se">\&quot;</span><span class="s2">&quot;</span>
<span class="n">Out</span><span class="p">:</span> <span class="s2">&quot;0&quot;</span>
</pre></div>
</div>
</li>
<li><p class="first"><em>float-to-string</em></p>
<p>Converts a Common Lisp float into a string suitable for a PostgreSQL float:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">In</span><span class="p">:</span> <span class="mf">100.0</span><span class="n">d0</span>
<span class="n">Out</span><span class="p">:</span> <span class="s2">&quot;100.0&quot;</span>
</pre></div>
</div>
</li>
<li><p class="first"><em>set-to-enum-array</em></p>
<p>Converts a string representing a MySQL SET into a PostgreSQL Array of
Enum values from the set.</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">In</span><span class="p">:</span> <span class="s2">&quot;foo,bar&quot;</span>
<span class="n">Out</span><span class="p">:</span> <span class="s2">&quot;{foo,bar}&quot;</span>
</pre></div>
</div>
</li>
<li><p class="first"><em>empty-string-to-null</em></p>
<p>Convert an empty string to a null.</p>
</li>
<li><p class="first"><em>right-trim</em></p>
<p>Remove whitespace at end of string.</p>
</li>
<li><p class="first"><em>remove-null-characters</em></p>
<p>Remove <cite>NUL</cite> characters (<cite>0x0</cite>) from given strings.</p>
</li>
<li><p class="first"><em>byte-vector-to-bytea</em></p>
<p>Transform a simple array of unsigned bytes to the PostgreSQL bytea Hex
Format representation as documented at
<a class="reference external" href="http://www.postgresql.org/docs/9.3/interactive/datatype-binary.html">http://www.postgresql.org/docs/9.3/interactive/datatype-binary.html</a></p>
</li>
<li><p class="first"><em>sqlite-timestamp-to-timestamp</em></p>
<p>SQLite type system is quite interesting, so cope with it here to produce
timestamp literals as expected by PostgreSQL. That covers year only on 4
digits, 0 dates to null, and proper date strings.</p>
</li>
<li><p class="first"><em>sql-server-uniqueidentifier-to-uuid</em></p>
<p>The SQL Server driver receives data fo type uniqueidentifier as byte
vector that we then need to convert to an UUID string for PostgreSQL
COPY input format to process.</p>
</li>
<li><p class="first"><em>unix-timestamp-to-timestamptz</em></p>
<p>Converts a unix timestamp (number of seconds elapsed since beginning of
1970) into a proper PostgreSQL timestamp format.</p>
</li>
<li><p class="first"><em>varbinary-to-string</em></p>
<p>Converts binary encoded string (such as a MySQL <cite>varbinary</cite> entry) to a
decoded text, using the table’s encoding that may be overloaded with the
<em>DECODING TABLE NAMES MATCHING</em> clause.</p>
</li>
</ul>
</div></blockquote>
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