Spatialite does not use gpkg_spatial_ref_sys in GPKG mode

Question

Spatialite and GPKG mode are enabled:

SELECT load_extension('mod_spatialite');
SELECT EnableGpkgMode();

Spatialite knows about gpkg_spatial_ref_sys (gpkgInsertEpsgSRID() uses it), and the table is populated:

sqlite> SELECT srs_name, srs_id FROM gpkg_spatial_ref_sys;
Undefined cartesian SRS|-1
Undefined geographic SRS|0
WGS 84 geodetic|4326
Amersfoort / RD New|28992

Yet when I try to use ST_Transform() it tries to look for (and fails to find) spatial_ref_sys:

sqlite> SELECT ST_Transform(gpkgMakePoint(5.140743, 51.630698, 4326), 28992);
unknown SRID: 4326      <no such table: spatial_ref_sys>
unknown SRID: 28992     <no such table: spatial_ref_sys>
Error: ST_Transform exception - unable to find the origin SRID.

What am I doing wrong? Does GPKG mode not support ST_Transform()? What is gpkgInsertEpsgSRID() for then?

Version info:

sqlite> SELECT spatialite_version(), sqlite_version();
5.0.1|3.34.1

Answer 1

As @user30184 says it is in fact necessary to have a separate spatial_ref_sys table. However, instead of using InitSpatialMetadata() and getting many other tables, the following SQL seems to have worked as well (for ST_Transform() at least).

CREATE TABLE spatial_ref_sys (
  srid       INTEGER NOT NULL PRIMARY KEY,
  auth_name  VARCHAR(256),
  auth_srid  INTEGER,
  srtext     VARCHAR(2048),
  proj4text  VARCHAR(2048)
);
INSERT INTO spatial_ref_sys SELECT
  srs_id AS srid,
  organization AS auth_name,
  organization_coordsys_id AS auth_srid,
  definition AS srtext,
  NULL
FROM gpkg_spatial_ref_sys;