I have multiple tables in a PSQL/PostGIS database which are comprised of GPS locations of animals. The tables are uploaded into the database with latitude, longitude, and timestamp columns, and then I create geometry columns from the latitude/longitude columns as follows:

ALTER TABLE main.gps_animals_data ADD COLUMN geom geometry;

UPDATE main.gps_animals_data 
SET   geom = ST_Transform(ST_SetSRID(ST_MakePoint(longitude, latitude), 4326), 22234);

In this way, I assumed my SRID was set to the EPSG projection 22234, which is the UTM projection in my study area. However, when I try to do a simple spatial join between tables, I get a "mixed geometries" error (which I know means the tables don't share the same projection). I then try

SELECT Find_SRID('main', 'gps_animals_data', 'geom') , and it gives me 0.

I've tried updating my geometry column such as: UPDATE main.gps_animals_data SET geom = ST_SetSRID(geom, 22234);

as well as creating a new geometry column from the coordinates (again) but assigning them an 4326 SRID (in case there's something wrong with 22234 for whatever reason), and I've also tried modifying my spatial join query to explicitly assign an SRID, such as:

SELECT ST_Distance(
     ST_SetSRID(ST_MakePoint(t1.longitude, t1.latitude), 4326), 
     ST_SetSRID(geom_wgs84, 4326)) distance_apart

No matter what, I keep getting:

ERROR: Operation on mixed SRID geometries CONTEXT: parallel worker

Is there a reason that my tables are not storing the SRID's that I assign them, or are my commands not correct?

  • You really ought not be doing a ST_SetSRID on a stored column (more than once). If it's been set earlier to other than 4326, you need to ST_Transform to 4326. Also, to get geodesic distance, you need to cast both to geography. And your SELECT is missing a FROM in your code block.
    – Vince
    Commented Jan 22, 2022 at 2:44

1 Answer 1


When you add the geometry column to the table you need to set it's SRID

ALTER TABLE main.gps_animals_data ADD COLUMN geom geometry(Point, 4326);

Then PostGIS will know what is in that column when it comes to preparing your query.

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