qgis_process errors with 'native:dissolve' if SEPARATE_DISJOINT=true and if OUTPUT is an explicit file

[florisvdh]

What is the bug or the crash?

When running native:dissolve, qgis_process will error while writing to an explicit output file if SEPARATE_DISJOINT=true. An output file is written nevertheless.

With OUTPUT=TEMPORARY_OUTPUT this does not happen, but then no output file is available (= #51503).

The command succeeds if SEPARATE_DISJOINT=false, but setting as 'false' was not the purpose.

This issue may overlap with the needs to solve #53392.

Steps to reproduce the issue

Use the input.gpkg file inside input.gpkg.zip and save it in the working directory to reproduce below code.

$ ls output.gpkg
ls: cannot access 'output.gpkg': No such file or directory
$ 
$ qgis_process run 'native:dissolve' --INPUT=input.gpkg --FIELD=box --SEPARATE_DISJOINT=true --OUTPUT=output.gpkg

----------------
Inputs
----------------

FIELD:	box
INPUT:	input.gpkg
OUTPUT:	output.gpkg
SEPARATE_DISJOINT:	true


ERROR 1: failed to execute insert : UNIQUE constraint failed: output.fid
Could not write feature into OUTPUT
ERROR:	Could not write feature into OUTPUT
Could not write feature into OUTPUT
$ 
$ ls output.gpkg
output.gpkg
$ 
$ rm output.gpkg 
$ 
$ qgis_process run 'native:dissolve' --INPUT=input.gpkg --FIELD=box --SEPARATE_DISJOINT=true --OUTPUT=TEMPORARY_OUTPUT

----------------
Inputs
----------------

FIELD:	box
INPUT:	input.gpkg
OUTPUT:	TEMPORARY_OUTPUT
SEPARATE_DISJOINT:	true


0...10...20...30...40...50
----------------
Results
----------------

OUTPUT:	Dissolved_6d6932d5_59f8_443b_b40e_835747629ebb
$ 
$ ls Dissolved*
ls: cannot access 'Dissolved*': No such file or directory
$ 
$ qgis_process run 'native:dissolve' --INPUT=input.gpkg --FIELD=box --SEPARATE_DISJOINT=false --OUTPUT=output.gpkg

----------------
Inputs
----------------

FIELD:	box
INPUT:	input.gpkg
OUTPUT:	output.gpkg
SEPARATE_DISJOINT:	false


0...10...20...30...40...50
----------------
Results
----------------

OUTPUT:	output.gpkg
$ 
$ ls output.gpkg
output.gpkg

Versions

$ qgis_process --version
QGIS 3.34.1-Prizren 'Prizren' (133927424d9)
QGIS code revision 133927424d9
Qt version 5.15.3
Python version 3.10.12
GDAL/OGR version 3.6.4
PROJ version 9.1.1
EPSG Registry database version v10.076 (2022-08-31)
GEOS version 3.11.1-CAPI-1.17.1
SQLite version 3.37.2
OS Linux Mint 21.2

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

The input layer and the challenge are based on https://stackoverflow.com/q/77614772/15137041.

[florisvdh]

Confirmed that it works! 🎉 Thanks!!

$ ~/git_repositories2/QGIS/build-0aed505/output/bin/qgis_process run 'native:dissolve' --INPUT=input.gpkg --FIELD=box --SEPARATE_DISJOINT=true --OUTPUT=output.gpkg

----------------
Inputs
----------------

FIELD:	box
INPUT:	input.gpkg
OUTPUT:	output.gpkg
SEPARATE_DISJOINT:	true


0...10...20...30...40...50
----------------
Results
----------------

OUTPUT:	output.gpkg
$ 
$ ~/git_repositories2/QGIS/build-0aed505/output/bin/qgis_process --version | head -1
QGIS 3.35.0-Master 'Master' (0aed5058)

[dawgermany]

this is also true for the buffer algorithm when choosing separate_disjoint=true