Hi Daniel, Il giorno ven 22 gen 2021 alle ore 18:07 Daniel Baston <dbas...@gmail.com> ha scritto:
> It should be deterministic for most real data if the inputs are ordered > consistently, using the OVER() clause as you suggest. It's possible that > there may be a contrived situation involving duplicates in the input where > a result would be different (as GEOS STRtree is using std::sort instead of > std::stable_sort), but I'm not sure. Also, there are sometimes multiple > possible clusterings that satisfy the DBSCAN algorithm, so it is expected > that the results may differ from different implementations or different > orderings of the same input. > Thank you for the answer. I think I'll try to define the partition with the ORDER BY geom clause in order to check if I can obtain more determinism. If I correctly understood, the ORDER BY should add a further step with preordering the geometries using an Hilbert curve. Of course, this would impact the overall duration of the query. Giuseppe.
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