Sphere based calculations for geography don't appear to be faster?

[Marco Boeringa]

Hi,

After the PostGIS 3.4.3 release, that fixed an issue with sphere based 
calculations for geography type, I decided to run a quick test to see if 
sphere based calculations would give a performance benefit for my 
workflow. Due to the existing bug, I had been using spheroid based 
calculations exclusively up to now.

According to the Help (https://postgis.net/docs/ST_Area.html), the 
sphere based calculations should be faster. However, looking at the 
timings listed below, it appears there is no significant difference?

SQL used:

DROP MATERIALIZED VIEW IF EXISTS atest;
CREATE MATERIALIZED VIEW atest AS SELECT 
ST_AREA(way::geography,true/false) FROM planet_osm_polygon

The test data was the Geofabrik Italy extract, and used the polygon 
table of an osm2pgsql import containing +/- 19M records, containing 
polygons of varying sizes up to country size. The tests were run on a 
local dedicated system with plenty of IO and CPU.

Marco

*** SPHEROID ***:
Start time    2024-10-01 08:07:05.984
Finish time    2024-10-01 08:07:15.248

Start time    2024-10-01 08:08:13.881
Finish time    2024-10-01 08:08:24.362

Start time    2024-10-01 08:08:42.772
Finish time    2024-10-01 08:08:51.998

Start time    2024-10-01 08:09:16.137
Finish time    2024-10-01 08:09:26.484

*** SPHERE ***
Start time    2024-10-01 08:10:35.261
Finish time    2024-10-01 08:10:45.846

Start time    2024-10-01 08:11:05.856
Finish time    2024-10-01 08:11:16.110

Start time    2024-10-01 08:11:35.278
Finish time    2024-10-01 08:11:44.499

Start time    2024-10-01 08:12:18.769
Finish time    2024-10-01 08:12:29.020