I have a query where I use select ST_Extent(geometries) which returns a box2d object. I would like to cast it back to a geometry object since that is what I need but I was unable to do so with select ST_Extent(geometries)::geometry which returned only a set of numbers. I was also unable to find any alternatives. Also using another ST function would work for me but I was unable to find something suiting

  • That set of numbers is the bytea resentation of a GEOMETRY type. Geometries are byte encoded types by design, and all ST functionality is built on top of them - so for all intent and purpose, those numbers are correct. There are functions to deserialize the byte encoding into human readable format, primarily ST_AsText/ST_AsEWKT.
    – geozelot
    Jul 9 at 10:11

1 Answer 1


Running this query:

select st_extent(geom) as box,
  st_extent(geom)::geometry as g1,  
  st_asewkt(st_extent(geom)::geometry) as geom 
from osopen_zoomstack.boundaries

gives me the expected results.

"BOX(315261.25 185879.45,398017.01 657601.49)"  
"POLYGON((315261.25 185879.45,315261.25 657601.49,398017.01 657601.49,398017.01 185879.45,315261.25 185879.45))"
  • Thanks a lot :D exactly what I was looking for but wasn't able to find nowhere :)
    – Tenebris
    Jul 9 at 10:05

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