[postgis-users] Counting intersecting polygons

Arnaud L. arnaud.listes at codata.eu
Mon May 27 23:36:59 PDT 2019

Le 27/05/2019 à 14:47, Marcin Mionskowski a écrit :
> SELECT COUNT(DISTINCT t1.column_with_unique_ids)
> FROM Table_1 t1
> 	,Table_2 t2
> WHERE ST_Intersects(t1.wkb_geometry,t2.wkb_geometry)

Unless you're running PG12 and PostGIS 3 (see Paul Ramsey's latest 
post), the "WHERE EXISTS" construct will be able to trigger a parallel 
query plan whereas the "JOIN" construct will not.


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