SFCGAL (https://oslandia.gitlab.io/SFCGAL/) is a C++ wrapper library around the geometry library CGAL (https://www.cgal.org/) that provides advanced 2D and 3D spatial functions.
In PostGIS the SFCGAL extension has to be created in order to call the CGAL functions:
postgres=# create extension postgis_sfcgal;
When the extension is not created and you are using a function from CGAL (for example st_Extrude) the following vague error will occur:
postgres=# select ST_Extrude(ST_Buffer(ST_GeomFromText('POINT(100 90)'),50, 'quad_segs=2'),0,0,30);
SQL Error [42883]: ERROR: function st_extrude(geometry, integer, integer, integer) does not exist
Hint: No function matches the given name and argument types. You might need to add explicit type casts.
Position: 8
In https://postgis.net/docs/reference.html#reference_sfcgal there is a list of SFCGAL functions:
postgis_sfcgal_version ST_Extrude ST_StraightSkeleton ST_ApproximateMedialAxis ST_IsPlanar ST_Orientation ST_ForceLHR ST_MinkowskiSum ST_ConstrainedDelaunayTriangles ST_3DIntersection ST_3DDifference ST_3DUnion ST_3DArea ST_Tesselate ST_Volume ST_MakeSolid ST_IsSolid
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