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From: Emi Lu <emilu@encs.concordia.ca>
To: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: char(N), varchar(N), varchar, text
Date: Wed, 08 Oct 2014 10:22:44 -0400
Message-ID: <543548B4.4060700@encs.concordia.ca> (raw)
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    <small>Good morning, <br>
      <br>
      For performance point of view, are there big differences between:
      char(N), varchar(N), varchar, text? <br>
    </small>
    <p><small>Some comments from google shows: <br>
        No difference, under the hood it's all varlena. Check this
        article from Depesz: <a
href="http://www.depesz.com/index.php/2010/03/02/charx-vs-varcharx-vs-varchar-vs-text/">http://www....;
        A couple of highlights:</small></p>
    <small>
    </small>
    <blockquote><small> </small>
      <p><small>To sum it all up:</small></p>
      <small> </small>
      <ul>
        <li><small>char(n) &#8211; takes too much space when dealing with
            values shorter than n, and can lead to subtle errors because
            of adding trailing spaces, plus it is problematic to change
            the limit</small></li>
        <li><small>varchar(n) &#8211; it's problematic to change the limit in
            live environment</small></li>
        <li><small>varchar &#8211; just like text</small></li>
        <li><small>text &#8211; for me a winner &#8211; over (n) data types because
            it lacks their problems, and over varchar &#8211; because it has
            distinct name</small></li>
      </ul>
      <small>
        So, can I assume no big performance differences? <br>
        Thanks alot!<br>
        Emi<br>
      </small></blockquote>
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