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<DIV><FONT face="Courier New" size=2><SPAN
class=153590114-03082010>Hi</SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2><SPAN
class=153590114-03082010></SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2><SPAN class=153590114-03082010>I'm writing
a function in PSQL to update a stream network containing multilinestrings with
XYZM.</SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2><SPAN class=153590114-03082010>The problem
is to get a linestring by sewing together multilinestrings with
ST_LineMerge.</SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2><SPAN class=153590114-03082010>It seems to
me that ST_LineMerge cannot handle M-values.</SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2><SPAN
class=153590114-03082010></SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2><SPAN class=153590114-03082010>My approach
is:</SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2><SPAN
class=153590114-03082010></SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2><SPAN class=153590114-03082010>First I join
two or more multilinestrings (ST_Union only gives XYZ)</SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2><SPAN
class=153590114-03082010></SPAN></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2>select
ST_AsEwkt(ST_Collect(ST_GeomFromText('MULTILINESTRING((1 1 11 1, 2 2 22 2, 3 3
33 3),(3 3 33 3, 4 4 44 4, 5 5 55 5))'),<SPAN class=153590114-03082010>
</SPAN>ST_GeomFromText('MULTILINESTRING(( 5 5 55 5, 6 6 66 6, 7 7 77 7),(7 7 77
7, 8 8 88 8))')));</FONT>
</DIV>
<DIV><FONT face="Courier New" size=2></FONT>
</DIV>
<DIV><SPAN class=153590114-03082010><FONT face="Courier New" size=2>-->
"GEOMETRYCOLLECTION(MULTILINESTRING((1 1 11 1,2 2 22 2,3 3 33 3),(3 3 33 3,4 4
44 4,5 5 55 5)),MULTILINESTRING((5 5 55 5,6 6 66 6,7 7 77 7),(7 7 77 7,8 8 88
8)))"</FONT></SPAN>
</DIV>
<DIV><FONT face="Courier New" size=2></FONT>
</DIV>
<DIV><FONT face="Courier New" size=2></FONT>
</DIV>
<DIV><SPAN class=153590114-03082010><FONT face="Courier New" size=2>then I tried
to make a linestring</FONT></SPAN>
</DIV>
<DIV><SPAN class=153590114-03082010><FONT face="Courier New"
size=2></FONT></SPAN>
</DIV>
<DIV><SPAN class=153590114-03082010><FONT face="Courier New" size=2>select
ST_AsEwkt(ST_Force_4D(ST_LineMerge(ST_CollectionExtract((select
ST_Collect(ST_GeomFromText('MULTILINESTRING((1 1 11 1, 2 2 22 2, 3 3 33 3),(3 3
33 3, 4 4 44 4, 5 5 55 5))'), ST_GeomFromText('MULTILINESTRING(( 5 5 55 5, 6 6
66 6, 7 7 77 7),(7 7 77 7, 8 8 88 8))'))),2))));</FONT></SPAN>
</DIV>
<DIV><SPAN class=153590114-03082010><FONT face="Courier New"
size=2></FONT></SPAN>
</DIV>
<DIV><SPAN class=153590114-03082010><FONT face="Courier New" size=2>-->
"LINESTRING(1 1 11 0,2 2 22 0,3 3 33 0,4 4 44 0,5 5 55 0,6 6 66 0,7 7 77 0,8 8
88 0)"</FONT></SPAN>
</DIV>
<DIV><SPAN class=153590114-03082010><FONT face="Courier New"
size=2></FONT></SPAN>
</DIV>
<DIV><SPAN class=153590114-03082010><FONT face="Courier New" size=2>I tried
several ways but the M-Value is always lost. In the documentation for
St_LineMerge there is no hint about 3D or 4D support.</FONT></SPAN>
</DIV>
<DIV><SPAN class=153590114-03082010><FONT face="Courier New"
size=2></FONT></SPAN>
</DIV>
<DIV><FONT face="Courier New"></FONT><SPAN class=153590114-03082010><FONT
size=2><FONT face="Courier New"></FONT>
</DIV>
<DIV><FONT face="Courier New">Regards,</FONT>
</DIV>
<DIV><FONT face="Courier New">Peter</FONT>
</DIV>
<DIV></FONT></SPAN>
</DIV></BODY></HTML>