I would imagine that running GETNUMELEM against a MultiPoint would return the number of points in the MultiPoint, but it seems to always return 1. I'm comparing it with ST_NumGeometries in other databases. I'm sure I could hack it with a call to SDO_UTIL.GETNUMVERTICES and a case statement but this seems like a bug to me. Surely the intention of GETNUMELEM on a MultiPoint can't be to always return 1?
SDO_UTIL.GETNUMELEM in Oracle Spatial doesn't seem right against MultiPoint types. Is this a defect?
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Could you add the SDO geometry as text? Or check yourself if you really have MultiPoint and not Point cluster gis.stackexchange.com/questions/206659/….– user30184Commented Aug 23, 2023 at 15:32
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You are right!!! The library I was using was incorrectly creating a point cluster vs. a MultiPoint. My bad. If you want to put that as the answer I can mark it as answered. THANK YOU!!!– Yndigo DreamCommented Aug 28, 2023 at 18:35
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1 Answer
Multiple points can be stored into a sdo_geometry either as a MultiPoint or as a PointCluster. MultiPoint contains points as elements, which means by the same that the sdo_elem_info_array has as many triplets as there are point elements in the MultiPoint. For example
sdo_geometry (2005, null, null,
sdo_elem_info_array (1,1,1, 3,1,1, 5,1,1),
sdo_ordinate_array (65,5, 70,7, 75,5)))
In a point cluster the points make a one entity and they cannot be split into elements. As a difference to MultiPoint the sdo_elem_info_array contains only one triplet. For example
sdo_geometry (2005, null, null,
sdo_elem_info_array (1,1,3),
sdo_ordinate_array (50,5, 55,7, 60,5)))
The sdo_geometry examples taken from https://gis.stackexchange.com/a/233958/30184
