<div>Estou a tentar fazer uma agregação (dissolve) no Spatialite 3.0.1 em Windows Vista.</div><div><br></div><div>Tenho uma tabela chamada "tableA" com 72000 registos, com uma coluna Geometry e uma de texto chamada "field1". Quero agregar todos os poligonos com base no atributo "field1".</div>
<div><br></div><div>Tentei o seguinte:</div><div><br></div><div><pre class="lang-sql prettyprint" style="margin-top:0px;margin-bottom:10px;padding:5px;border:0px;font-size:12px;vertical-align:baseline;overflow:auto;width:auto;max-height:600px;font-family:Consolas,Menlo,Monaco,'Lucida Console','Liberation Mono','DejaVu Sans Mono','Bitstream Vera Sans Mono','Courier New',monospace,serif;background-color:rgb(238,238,238);color:rgb(57,51,24);line-height:18px">
<code style="margin:0px;padding:0px;border:0px;vertical-align:baseline;font-family:Consolas,Menlo,Monaco,'Lucida Console','Liberation Mono','DejaVu Sans Mono','Bitstream Vera Sans Mono','Courier New',monospace,serif;color:rgb(34,34,34)"><span class="kwd" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(138,74,11)">Select</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"> f</span><span class="pun" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(20,86,128)">.</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black">field1 </span><span class="kwd" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(138,74,11)">as</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"> field1</span><span class="pun" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(20,86,128)">,</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"> st_union</span><span class="pun" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(20,86,128)">(</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black">f</span><span class="pun" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(20,86,128)">.</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black">geometry</span><span class="pun" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(20,86,128)">)</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"> </span><span class="kwd" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(138,74,11)">as</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"> geometry<br>
</span><span class="kwd" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(138,74,11)">From</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"> tableA </span><span class="kwd" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(138,74,11)">as</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"> f<br>
</span><span class="kwd" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(138,74,11)">Group</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"> </span><span class="kwd" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(138,74,11)">by</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"> field1</span><span class="pun" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:rgb(20,86,128)">;</span><span class="pln" style="margin:0px;padding:0px;border:0px;vertical-align:baseline;color:black"><br>
</span></code></pre><p style="margin:0px 0px 1em;padding:0px;border:0px;font-size:14px;vertical-align:baseline;clear:both;word-wrap:break-word;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;line-height:18px;background-color:rgba(248,248,248,0.6)">
e está a demorar demasiado tempo, acabei por cancelar o processo após cerca de 1 hora. Em ArcGIS a operação demorou cerca de 5 minutos, por isso devo estar a fazer alguma coisa mal.</p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-size:14px;vertical-align:baseline;clear:both;word-wrap:break-word;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;line-height:18px;background-color:rgba(248,248,248,0.6)">
Há alguma forma mais eficiente de executar esta operação em Spatialite?</p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-size:14px;vertical-align:baseline;clear:both;word-wrap:break-word;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;line-height:18px;background-color:rgba(248,248,248,0.6)">
<br></p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-size:14px;vertical-align:baseline;clear:both;word-wrap:break-word;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;line-height:18px;background-color:rgba(248,248,248,0.6)">
Coloquei esta mesma pergunta do gis.stackexchange caso queiram responder lá.</p></div><a href="http://gis.stackexchange.com/questions/35213/what-is-the-efficient-way-to-dissolve-polygons-using-spatialite-3-0">http://gis.stackexchange.com/questions/35213/what-is-the-efficient-way-to-dissolve-polygons-using-spatialite-3-0</a><div>
<br></div><div>Já agora alguém conhece alguma mailing list de Spatialite? Sabem se está activa?<br><div><br></div><div>Obrigado,</div><div><br></div><div>Alexandre Neto</div></div>