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<DIV><SPAN class=079392211-30082007><FONT face=Arial color=#0000ff size=2>OK, I
found a solution:</FONT></SPAN></DIV>
<DIV><SPAN class=079392211-30082007><FONT face=Arial color=#0000ff size=2>SELECT
multi(geomunion(geom)) from table1.</FONT></SPAN></DIV>
<DIV><SPAN class=079392211-30082007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=079392211-30082007><FONT face=Arial color=#0000ff size=2>Now I
want to use this query to get the number of holes in the union of all
geometries:</FONT></SPAN></DIV>
<DIV><SPAN class=079392211-30082007><FONT face=Arial color=#0000ff size=2>SELECT
NumInteriorRings(multi(geomunion(geom))) FROM table1</FONT></SPAN></DIV><SPAN
class=079392211-30082007></SPAN><FONT face=Tahoma>
<DIV><FONT size=2><SPAN class=079392211-30082007><FONT face=Arial
color=#0000ff></FONT></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=079392211-30082007>This
queries perform very very bad. I cancelled a query on a table with about 10000
geometries because it takes over an hour without being completed. Is there a
better way to union such a big number of geometries?</SPAN></FONT></DIV>
<DIV><FONT size=2><SPAN class=079392211-30082007></SPAN></FONT> </DIV>
<DIV><FONT size=2><SPAN class=079392211-30082007> </SPAN>-----Ursprüngliche
Nachricht-----<BR><B>Von:</B> postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net]<B>Im Auftrag von
</B>Thorsten Kraus<BR><B>Gesendet:</B> Donnerstag, 30. August 2007
12:54<BR><B>An:</B> PostGisMailingList (E-Mail)<BR><B>Betreff:</B>
[postgis-users] Geomunion<BR><BR></DIV></FONT></FONT>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px"><!-- Converted from text/rtf format -->
<P><FONT face=Arial size=2>Hello,</FONT> </P>
<P><FONT face=Arial size=2>I want to union all geometries of a table into one
big geometry. Do you know how this task can be performed the best
way?</FONT></P>
<P><FONT face=Arial size=2>Regards,</FONT> <BR><FONT face=Arial
size=2>Thorsten</FONT> </P></BLOCKQUOTE></BODY></HTML>