[PostGIS] #5844: ST_AsMVTGeom producing null results on valid geoms

[PostGIS]

#5844: ST_AsMVTGeom producing null results on valid geoms
-----------------------+-------------------------------
 Reporter:  pratishta  |      Owner:  pramsey
     Type:  defect     |     Status:  new
 Priority:  medium     |  Milestone:  PostGIS Packaging
Component:  postgis    |    Version:  3.2.x
 Keywords:             |
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 We're working on an application with a map that gets Mapbox vector tiles
 from our backend API. Our API generates these tiles from a database that's
 hosted here Digital Ocean. However, the behavior of the app differs from
 the locally hosted database and the one on DO. Specifically, some tiles
 are missing at certain zoom levels and x, y coordinates.

 We've provided a repository with a database schema and data to populate to
 reproduce this issue: https://github.com/pratishta/do-postgres-support

 The following query produces null values on the existing database in DO.
 It does not produce null values when run on a local database with the same
 data. The PostGIS functions seem to be the points of difference,
 specifically ST_AsMVTGeom.


 {{{
 SELECT
         id,
         ST_AsMVTGeom(mercator_fill, ST_TileEnvelope(10, 301, 385), 4096,
 64, true) as geomFill
 FROM city_council_district
 WHERE ST_Intersects(mercator_fill, ST_TileEnvelope(10, 301, 385));
 }}}


 PostGIS versions using `SELECT PostGIS_Full_Version();`

 Local database:


 {{{
 POSTGIS="3.5.1 48ab069" [EXTENSION] PGSQL="150" GEOS="3.11.1-CAPI-1.17.1"
 PROJ="9.1.1 NETWORK_ENABLED=OFF URL_ENDPOINT=https://cdn.proj.org
 USER_WRITABLE_DIRECTORY=/var/lib/postgresql/.local/share/proj
 DATABASE_PATH=/usr/share/proj/proj.db" LIBXML="2.9.14" LIBJSON="0.16"
 LIBPROTOBUF="1.4.1" WAGYU="0.5.0 (Internal)" (core procs from "3.4.2
 c19ce56" need upgrade)
 }}}

 DO database:


 {{{
 POSTGIS="3.2.6 5ea52a731b3" [EXTENSION] PGSQL="150"
 GEOS="3.9.2-CAPI-1.14.3" PROJ="7.2.1" LIBXML="2.10.4" LIBJSON="0.17"
 LIBPROTOBUF="1.4.1" WAGYU="0.5.0 (Internal)" (core procs from "3.2.4
 23.10.1-282-g0354378dc6" need upgrade)
 }}}

 But even when both databases are on the same version, this problem
 persists.

 Could we get some information on what else could be impacting the results
 if the data and PostGIS versions are the same? In what cases does
 `ST_AsMVTGeom` meant to result in a null value?
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5844>
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