[postgis-devel] Proposal: ST_Overlay function

[Martin Davis]

Thanks for the vote of approval!

And also for the thought-provoking ideas about a function signature for
full overlay, and about grid-based parallelization.  Will keep those in
mind for if and when there is time to work on this.

On Thu, Nov 26, 2020 at 2:05 PM Andrew Joseph <ap.joseph at live.com> wrote:

> This would be incredibly useful and likely become one of the most used
> functions in Postgis!
>
>
> Personally I think the simplest most intuitive function definition would be
>
>
>
> st_polygonal_overlay(idpoly[]) RETURNS SETOF idpolyportion;
>
> CREATE TYPE idpoly(
>
>   id integer,
>
>    geom geometry(Polygon)
>
> );
>
>
>
>
>
> CREATE TYPE idpoly_portion(
>
>   parent_ids integer[],
>
>   geom geometry(Polygon)
>
> );
>
>
>
> This would make it trivial to recombine the geometries with the originals.
>
> The biggest question I’d have would be how would parallelization work?
> Might be helpful to have another function that would create an ideal grid
> for clipping input geometries maybe something like:
>
>
>
> st_create_parallel_overlay_grid(geoms geometry[], numcores integer,
> max_mem_per_grid integer) RETURNS box2d;
>
> This way you could spread out st_polygonal_overlay across cores, then
> recombine using st_union by comparing parent_ids.
>
>
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
>
>
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