Not all geometry types are found in PostGIS table with Spatial Type of Geometry

[rgreenwood]

Describe the bug
When connecting to a PostGIS table with Spatial Type of "Geometry" not all of the geometry types in the table were detected.

How to Reproduce
Attached is a PostgeSQL backup file multiple_gometries.backup.zip containing a single table with approx 11,000 rows, the "first" ~7,000 of which are LineStrings and the "last" is a Polygon and the rest are Points. I put "first" and "last" in quotes because I'm not explicitly ordering the data, it was put into the table in that sequence and might not remain so after vacuuming. When connecting to this table only one entry appears in the in the Connections list and that is of type LineString. There should be three entries of type Point, LineString, and Polygon. So it seems that QGIS is not looking at all rows to find all geometry types.

QGIS and OS versions
3.18.2 on Ubuntu 20.04

[gioman]

SELECT DISTINCT ST_GeometryType(wkb_geometry)
FROM work.tracts;

"ST_LineString"
"ST_Polygon"
"ST_Point"

SELECT ogc_fid, ST_GeometryType(wkb_geometry)
FROM work.tracts
WHERE ST_GeometryType(wkb_geometry)='ST_Polygon';

7855 "ST_Polygon"

The polygon feature can be added with DB Manager ("Add layer advanced") and they show in the canvas, but the QGIS log registers:

2021-05-12T17:37:57 WARNING Feature type or srid for wkb_geometry of "work"."tracts" could not be determined or was not requested.

On master/ubuntu I can see both the point and line features in the browser and the "add postgis layer" dialog.

[elpaso]

@rgreenwood there is an hardcoded limit in the QGIS implementation that prevents a full table scan. I'll check if it can be removed without risks.