Paris Code Sprint 2016 : PostGIS Agenda

Discussion and group review topics for the Paris Code Sprint 2016.

Discussion

• Clustering functions: Aggregate or Window?
  • What naming convention
  • What to do with the existing aggregate functions
• Expanded object headers, introduction and testing
  • How they work
  • Potential advantages, disadvantages
  • Discussion on clean implementation possibilities
  • Testing and benchmarks, is it worth it?
• Alternate storage formats, beyond GSERIALIZED
  • Reasoning
  • How to add (version flags?)
  • Multiple co-existing formats?
• Breaking raster out as postgis_raster extension (hold off on talking about this until Regina comes)
  • Implications / difficulties
• GEOS improvements that would help PostGIS
• Way to know/be sure a geometry is valid, without need to launch an IsValid test (SFCGAL initial purpose)
• Using FDW with PostGIS (hold off on talking about this until Regina comes)
  • Functions pushdown
  • Current limitations
• PostgreSQL improvements that would help PostGIS
  • Parallel query, review experiments, plan and execute more (hold off on talking about this until Regina comes)
  • Feed back parallel query results to pgsql-hackers
• Open pull requests from GitHub
  • Merge, modify, or reject
• Tickets with design implications
  • https://trac.osgeo.org/postgis/ticket/2529
  • https://trac.osgeo.org/postgis/ticket/3405
  • https://trac.osgeo.org/postgis/ticket/3246
  • https://trac.osgeo.org/postgis/ticket/3326
• Do we want to bundle example datasets w/PostGIS for docs, tutorials?
• Adding more checks to automated builds?
  • valgrind (would need to add suppressions for GEOS leaks)
  • gcov (identify untested or unused code paths)

Tasks

• Benchmarking of expanded object headers test branch
• Benchmarking of parallel query and parallel aggregate work from pgsql-hackers

• BRIN indexes implementation for PostGIS geometries
• postgis/lwgeom_in_* move to liblwgeom dir (or any code that doesn't depend on Postgres?)

Possible PostGIS function improvement and addition

• improvement
  • st_pointN -> make a negative input count backward [rémi]
  • st_setPoint -> make a negative input count backward [rémi]
  • st_asText -> optionnal arg to limit digit number [marc]
  • st_centroid -> work on circular string (simply dump points, then classical centroid) [remi]
  • st_exteriorRing -> make it work on multipolygon, returns a collection
  • st_makeline -> make it work on multipoints [pauln]
  • st_scale -> optionnal argument to define the center of scaling (allows to scale "in place") [marc]
  • st_split -> allow splitting (multi)line by (multi)point
  • st_asgml -> allow GML 3.2.1 support (not only namespace handle) http://portal.opengeospatial.org/files/?artifact_id=26765
  • st_asgml (and st_geomfromgml) -> handle gml:Envelope
  • ST_AsX3D -> Bug fix - how to determine if 3D geometry is convex without resorting to CGAL. http://trac.osgeo.org/postgis/ticket/3435 [regina]
  • ST_GeogFromText -> make the longitude swap 180 deg when entering a latitude over 90 (postgis already counts the latitude backwards from 90 when crossing)
• slight addition
  • st_angle(P1,P2,P3) [remi]
  • st_MakeRing((multi) linestrings and/or points
  • st_DumpLines -> dump everything to line (rings in poly, lines in multilines, etc. )
  • st_DumpSegments -> dump segments (in the mathematical sense), that is every consecutive pairs of points in lines
• big addition
  • generate grid (regular and hex)
  • st_snapToLine -> st_snap = snap vertex to vertex. This one = snap vertex to vertex or edge. (note: st_snap also snap line to vertex)
  • st_splitLineByPoint(line,point,tolerance) -> using curv absc, the only current way to not be sensible to precision issue (st_split doesnt work)
  • st_VariableBuffer(geomM) -> buffer on geometry, the radius is given by M of each vertex, linear transition between. A lots of uses
  • St_FindCurve(geom,radius_range,min_number_of_support_points,tolerance) -> in a classical geometry, find the point describing arcs
  • St_MakeArc(P1,P2,centre) and St_MakeArc(P1,P2,radius) -> create arcs (_not_ using 3 points on arc!)
  • St_OrientedBBox(geom) -> returns the oriented bbox of the geom (returns a geom and an angle)
  • ST_KMeans -> window function - pramsey to integrate into 2.3 code base - https://github.com/pramsey/postgis/tree/kmeans