'what is the meaning of && in PostgreSQL?

In PostGIS, what is the result of the && operation between two geometries? In my mind, && returns a boolean, but does return geometry this time. In the following example, the operation is between a LineString and a Polygon.

Firstly, I guess this is the relationship between inclusion and being included. Until I do the following example, I think this should be a relationship of type "intersection". Am I right?

select ST_geomfromtext('linestring(0.1 0.1,1.9 1.9)', 4326) && st_geomfromtext('POLYGON((0 0,0 1,1 1,1 0,0 0))', 4326)

The result is t which represents true.

postgresqlpostgis


Solution 1:[1]

It's an intersection operator &&

boolean &&( geometry A , geometry B );

boolean &&( geography A , geography B );

The && operator returns TRUE if the 2D bounding box of geometry A intersects the 2D bounding box of geometry B.

How one could find it using google:

  1. Search for "postgis operators"
  2. On the first page https://postgis.net/docs/reference.html search for &&

Solution 2:[2]

diff between && and st_intersect.
https://postgis.net/docs/ST_Intersects.html

If a geometry or geography shares any portion of space then they intersect. For geography -- tolerance is 0.00001 meters (so any points that are close are considered to intersect)

So it's possible that boolean &&( geometry A , geometry B ); return true, but st_intersects(geometry A, geometry B) return false. example: https://postgis.net/workshops/postgis-intro/indexing.html

But boolean st_intersects(geometry A, geometry B) will yield the same result as boolean &&( geometry A , geometry B );

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Solution 1 Community
Solution 2 Mark

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