[postgis-tickets] [PostGIS] #4675: Implement topology.GetRingEdges in C

[PostGIS]

#4675: Implement topology.GetRingEdges in C
--------------------------+---------------------------
  Reporter:  strk         |      Owner:  strk
      Type:  enhancement  |     Status:  closed
  Priority:  medium       |  Milestone:  PostGIS 3.1.0
 Component:  topology     |    Version:  3.0.x
Resolution:  fixed        |   Keywords:
--------------------------+---------------------------

Comment (by strk):

 For the record, the C version is 21% faster.

 Tested with following input:
 {{{
 SELECT DropTopology('city_data');

 \i topology/test/load_topology.sql

 select
 topology.TopoGeo_AddPolygon('city_data',ST_Translate(ST_GetFaceGeometry('city_data',face_id),
 10, 10)) from city_data.face where face_id >0;
 select
 topology.TopoGeo_AddPolygon('city_data',ST_Translate(ST_GetFaceGeometry('city_data',face_id),
 11, 10)) from city_data.face where face_id >0;
 select
 topology.TopoGeo_AddPolygon('city_data',ST_Translate(ST_GetFaceGeometry('city_data',face_id),
 12, 10)) from city_data.face where face_id >0;
 select
 topology.TopoGeo_AddPolygon('city_data',ST_Translate(ST_GetFaceGeometry('city_data',face_id),
 13, 10)) from city_data.face where face_id >0;
 select
 topology.TopoGeo_AddPolygon('city_data',ST_Translate(ST_GetFaceGeometry('city_data',face_id),
 16, 10)) from city_data.face where face_id >0;

 select
 topology.TopoGeo_AddPolygon('city_data',ST_Translate(ST_GetFaceGeometry('city_data',face_id),
 10, 11)) from city_data.face where face_id >0;
 select
 topology.TopoGeo_AddPolygon('city_data',ST_Translate(ST_GetFaceGeometry('city_data',face_id),
 10, -20)) from city_data.face where face_id >0;
 }}}

 And following query:
 {{{
 explain (analyze, buffers)
 select count(*) from (
  select edge_id, (getRingEdges('city_data', edge_id)).*
  from city_data.edge
 ) foo;
 }}}

 Results in following plans:

 PLPGSQL:
 {{{
 Aggregate  (cost=5040787.79..5040787.79 rows=1 width=8) (actual
 time=2646.457..2646.457 rows=1 loops=1)
   Buffers: shared hit=804888
   ->  Result  (cost=0.29..4921412.79 rows=9550000 width=12) (actual
 time=54.797..2634.831 rows=258613 loops=1)
         Buffers: shared hit=804888
         ->  ProjectSet  (cost=0.29..50912.79 rows=9550000 width=32)
 (actual time=54.792..2609.541 rows=258613 loops=1)
               Buffers: shared hit=804888
               ->  Index Only Scan using edge_data_pkey on edge_data
 (cost=0.29..727.53 rows=9550 width=4) (actual time=0.024..3.815 rows=9550
 loops=1)
                     Heap Fetches: 0
                     Buffers: shared hit=146
 Planning Time: 0.319 ms
 JIT:
   Functions: 6
   Options: Inlining true, Optimization true, Expressions true, Deforming
 true
   Timing: Generation 0.362 ms, Inlining 31.182 ms, Optimization 11.497 ms,
 Emission 11.008 ms, Total 54.049 ms
 Execution Time: 2674.792 ms
 }}}

 C:
 {{{
 Aggregate  (cost=311174.16..311174.17 rows=1 width=8) (actual
 time=2072.915..2072.915 rows=1 loops=1)
   Buffers: shared hit=824179
   ->  Result  (cost=0.29..191799.16 rows=9550000 width=12) (actual
 time=19.584..2059.942 rows=258613 loops=1)
         Buffers: shared hit=824179
         ->  ProjectSet  (cost=0.29..48549.16 rows=9550000 width=32)
 (actual time=19.576..2034.256 rows=258613 loops=1)
               Buffers: shared hit=824179
               ->  Index Only Scan using edge_data_pkey on edge_data
 (cost=0.29..727.53 rows=9550 width=4) (actual time=0.034..3.536 rows=9550
 loops=1)
                     Heap Fetches: 0
                     Buffers: shared hit=146
 Planning Time: 0.312 ms
 JIT:
   Functions: 6
   Options: Inlining false, Optimization false, Expressions true, Deforming
 true
   Timing: Generation 0.443 ms, Inlining 0.000 ms, Optimization 0.144 ms,
 Emission 2.760 ms, Total 3.346 ms
 Execution Time: 2107.907 ms
 }}}

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4675#comment:3>
PostGIS <http://trac.osgeo.org/postgis/>
The PostGIS Trac is used for bug, enhancement & task tracking, a user and developer wiki, and a view into the subversion code repository of PostGIS project.