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Re: BUG #4810: Complex Contains, Bad Performace.

From: Paul Matthews <plm(at)netspace(dot)net(dot)au>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #4810: Complex Contains, Bad Performace.
Date: 2009-05-17 10:36:19
Message-ID: 4A0FE8A3.7020700@netspace.net.au (view raw or flat)
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Tom Lane wrote:
<blockquote cite="mid:2470(dot)1242396221(at)sss(dot)pgh(dot)pa(dot)us" type="cite">
  <pre wrap="">"Paul Mathews" <a class="moz-txt-link-rfc2396E" href="mailto:plm(at)netspace(dot)net(dot)au">&lt;plm(at)netspace(dot)net(dot)au&gt;</a> writes:
  </pre>
  <blockquote type="cite">
    <pre wrap="">Despite the existence of the index, postgresql is determined to full table
scan when given.
  SELECT 
    postcode
  WHERE
    boundary @&gt; point 'x,y';
    </pre>
  </blockquote>
  <pre wrap=""><!---->
polygon @&gt; point isn't an indexable operator.  The indexable operators
for a gist index on polygon are

 &lt;&lt;(polygon,polygon)
 &amp;&lt;(polygon,polygon)
 &amp;&amp;(polygon,polygon)
 &amp;&gt;(polygon,polygon)
 &gt;&gt;(polygon,polygon)
 ~=(polygon,polygon)
 @&gt;(polygon,polygon)
 &lt;@(polygon,polygon)
 &amp;&lt;|(polygon,polygon)
 &lt;&lt;|(polygon,polygon)
 |&gt;&gt;(polygon,polygon)
 |&amp;&gt;(polygon,polygon)
 ~(polygon,polygon)
 @(polygon,polygon)

So it looks like you need to convert the point to a one-point polygon.

			regards, tom lane

  </pre>
</blockquote>
WHERE<br>
&nbsp;&nbsp; g.boundary @&gt; polygon(box(w.geocode,w.geocode));<br>
<br>
Is there are more convenient, less ugly, way to convert a point to a
polygon?<br>
<br>
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