<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">Just to add that the equivalent
dissolve tool in 2.18.25 completes successfully on the data.<br>
<br>
On 19/11/2018 14:47, Andrew Harfoot wrote:<br>
</div>
<blockquote type="cite"
cite="mid:5a4aab80-14e4-94de-f8b5-d0054a5ec1a5@geodata.soton.ac.uk">
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<p>I'm seeing very strange behaviour with a particular shapefile
in QGIS 3.4.1. The data can be obtained here:</p>
<p><a class="moz-txt-link-freetext"
href="https://drive.google.com/file/d/1BPVnsUbJREYh6TvLM07GAzXMiMneHemN/view?usp=sharing"
moz-do-not-send="true">https://drive.google.com/file/d/1BPVnsUbJREYh6TvLM07GAzXMiMneHemN/view?usp=sharing</a></p>
<p> When I run the <i>Vector Geometry > Dissolve</i>
Processing tool on it, no errors are raised, an output layer is
created containing one row with no geometry. This happens
regardless of the Processing 'Invalid features filtering'
setting.<br>
<br>
Running the <i>GDAL > Vector geoprocessing > Dissolve</i>
tool on the data immediately returns an invalid geometry (self
intersection) error, but running <i>Vector Geometry > Check
validity</i> finds no errors using either the GEOS or QGIS
engine.<br>
<br>
If the <i>Vector Geometry > Dissolve</i> tool is run on a
selection from the shapefile, it will complete successfully if
all but one feature is selected, <b>regardless of which feature
is left unselected</b>.</p>
<p>I'm not sure whether this is a bug, or my data. Does anyone
have any explanation for the observed behaviour?</p>
<p>Cheers,</p>
<p>Andy<br>
</p>
<pre class="moz-signature" cols="72">--
Andy Harfoot
GeoData Institute
University of Southampton
Southampton
SO17 1BJ
Tel: +44 (0)23 8059 2719
<a class="moz-txt-link-abbreviated" href="http://www.geodata.soton.ac.uk" moz-do-not-send="true">www.geodata.soton.ac.uk</a>
</pre>
</blockquote>
<p><br>
</p>
<pre class="moz-signature" cols="72">--
Andy Harfoot
GeoData Institute
University of Southampton
Southampton
SO17 1BJ
Tel: +44 (0)23 8059 2719
<a class="moz-txt-link-abbreviated" href="http://www.geodata.soton.ac.uk">www.geodata.soton.ac.uk</a>
</pre>
</body>
</html>