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<DIV><FONT face=Arial color=#000000 size=2>I recall we were discussing a need for a split by function and that ST_GeometryN etc. is slow for large geometries. Unfortunately I don't have any humongous geometries to test with.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I just looked at ST_Dump (not sure why I never used it before, I guess because generate_series is more versatile.). Anyrate it seems to me it comes very close to a split by and with range ability. </FONT></DIV>
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<DIV><FONT face=Arial size=2>I presume ST_Dump is much more efficient than ST_GeometryN since it would make only one call out. Kevin can you test out that old generate_series one you had with dump?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>E.g. I can do this</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><BR>SELECT a.somefield1, a.somefield2, a.geom</DIV>
<DIV>FROM<BR>(SELECT somefield1, somefield2, (ST_Dump(the_geom)).*<BR>FROM sometablewithmulties) as a<BR>WHERE<BR>a.path[1] between 2 and 5;</DIV>
<DIV> </DIV>
<DIV>To grab all geometries in all records in a MULTI between 2 and 5 slot. Granted I can't think of a use for such a thing.</DIV>
<DIV> </DIV>
<DIV>Which allows me to wrap this in an sql function wrapper to generate a </DIV>
<DIV>pgis_GeometryRangeN(start int, end int) </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>or </DIV>
<DIV>pgis_GeometryAll() returns geometry[]</DIV>
<DIV> </DIV>
<DIV>similarly the below denatures a MULTIPOLYGON/LINESTRING to single POLYGON/LINESTRINGS<BR>SELECT a.somefield, (ST_Dump(the_geom)).geom<BR>FROM sometable as a;</DIV>
<DIV> </DIV>
<DIV>Which allows me to wrap this in a simple SQL function that does all sorts of split by stuff. E.g. for geometry collections I suppose it could get interesting with those multidimensional arrays. Unfortunately I guess ST_Dump is not going to deal with single geometries and breaking into points etc. But seems if its efficient for the other case - we can create a similar one to deal with the other cases by cutting and pasting some of the logic.</DIV>
<DIV> </DIV>
<DIV>Thanks,</DIV>
<DIV>Regina</DIV>
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