[gdal-dev] ogr2ogr from gpx to postgis - track_fid not maintained for track_points

[Michael Saupe]

I am referring to ogc_fid of 'tracks' table.


Am 02.01.2021 um 15:59 schrieb Michael Saupe:
> Hi Evan,
>
> thank you for the explanation. That makes sense. However, in my opinion ogr2ogr behavior is not really consistent in this case: The column ogc_fid , which is in fact the track id, is incremented on each gpx file import ( regardless if you use -update -append  or not ).
>
> Michael
>
> Am 02.01.2021 um 14:03 schrieb Even Rouault:
>> Michael,
>>
>> You have a single track in each file, so it is expected that track_fid doesn't
>> change and is set at 0 (as there's no attribute to uniquely identify a track)
>> For what you want to do (that is have distinct track_fid for each file),
>> you'll likely have to use an intermediate postgresql schema, where you would
>> correct the value of track_fid, before merging them together
>>
>> Even
>>
>>> clarification: second table of my points is 'track_points'.
>>>
>>> Also adding my 2 gpx files for reference:
>>>
>>> *file1.gpx:*
>>>
>>> <?xml version="1.0" encoding="UTF-8"?>
>>> <gpx version="1.1" xmlns="http://www.topografix.com/GPX/1/1">
>>>   <metadata>
>>>   </metadata>
>>>   <trk>
>>>     <trkseg>
>>>       <trkpt lat="49.250324000" lon="8.687196000">
>>>         <ele>1</ele>
>>>       </trkpt>
>>>       <trkpt lat="49.250019001" lon="8.687469003">
>>>         <ele>1</ele>
>>>       </trkpt>
>>>       <trkpt lat="49.249714001" lon="8.687742003">
>>>         <ele>1</ele>
>>>       </trkpt>
>>>     </trkseg>
>>>     <trkseg>
>>>       <trkpt lat="49.125652000" lon="8.714194000">
>>>         <ele>2</ele>
>>>       </trkpt>
>>>       <trkpt lat="49.125519000" lon="8.714731000">
>>>         <ele>2</ele>
>>>       </trkpt>
>>>       <trkpt lat="49.125414000" lon="8.715057001">
>>>         <ele>2</ele>
>>>       </trkpt>
>>>     </trkseg>
>>>   </trk>
>>> </gpx>
>>>
>>> *file2.gpx:*
>>>
>>> <?xml version="1.0" encoding="UTF-8"?>
>>> <gpx version="1.1" xmlns="http://www.topografix.com/GPX/1/1">
>>>   <metadata>
>>>   </metadata>
>>>   <trk>
>>>     <trkseg>
>>>       <trkpt lat="49.11" lon="8.7">
>>>         <ele>3</ele>
>>>       </trkpt>
>>>       <trkpt lat="49.12" lon="8.7">
>>>         <ele>3</ele>
>>>       </trkpt>
>>>       <trkpt lat="49.13" lon="8.7">
>>>         <ele>3</ele>
>>>       </trkpt>
>>>     </trkseg>
>>>   </trk>
>>> </gpx
>>>
>>> Am 01.01.2021 um 18:04 schrieb Michael Saupe:
>>>> Hello folks,
>>>>
>>>> I am importing multiple gpx files into a postgis database. The tables
>>>> 'tracks' and 'track_points' are created / updated.
>>>>
>>>> The column track_fid in in the track_points table should be a reference to
>>>> the track feature id as documented in
>>>> https://gdal.org/drivers/vector/gpx.html, however it is always zero.
>>>>
>>>> Is this a bug or am I missing something?
>>>>
>>>>       Details
>>>>
>>>> I am creating an empty database, then create postgis extension with
>>>> 'CREATE EXTENSION POSTGIS'
>>>>
>>>> I have two simple gpx files ( see attachments )
>>>>
>>>>   * file1.gpx - containing 2 track segments - each with 3 track points
>>>>   * file2.gpx - containing 1 track segment  with 3 track points
>>>>
>>>> I am using commands
>>>>
>>>> ogr2ogr -f PostgreSQL -update -append "PG:dbname=testdb host=localhost
>>>> user=postgres password=xx port=5432" file1.gpx
>>>>
>>>> ogr2ogr -f PostgreSQL -update -append "PG:dbname=testdb host=localhost
>>>> user=postgres password=xx port=5432" file2.gpx
>>>>
>>>> Resulting data in 'tracks'
>>>>
>>>> ogc_fid 	name 	cmt 	desc 	src 	link1_href 	link1_text 	link1_type
>>>> 	link2_href 	link2_text 	link2_type 	number 	type 	wkb_geometry 1
>> NULL
>>>> 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL
>> NULL 	... 2
>>>> 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL 	NULL
>> NULL 	NULL
>>>> 	...
>>> Resulting data in 'track_points'
>>>
>>> ogc_fid 	track_fid 	track_seg_id 	track_seg_point_id 	ele 	time 	....
>> other
>>> columns omitted ... 1 	0 	0 	0 	1 	NULL
>>> 2 	0 	0 	1 	1 	NULL
>>> 3 	0 	0 	2 	1 	NULL
>>> 4 	0 	1 	0 	2 	NULL
>>> 5 	0 	1 	1 	2 	NULL
>>> 6 	0 	1 	2 	2 	NULL
>>> 7 	0 	0 	0 	3 	NULL
>>> 8 	0 	0 	1 	3 	NULL
>>> 9 	0 	0 	2 	3 	NULL
>>>
>>>> Expected:
>>>>
>>>> ogc_fid 	track_fid 	track_seg_id 	track_seg_point_id 	ele 	time 	....
>>>> other columns omitted ... 1 	1
>>>>
>>>> 	0 	0 	1 	NULL
>>>>
>>>> 2 	1
>>>>
>>>> 	0 	1 	1 	NULL
>>>>
>>>> 3 	1
>>>>
>>>> 	0 	2 	1 	NULL
>>>>
>>>> 4 	1
>>>>
>>>> 	1 	0 	2 	NULL
>>>>
>>>> 5 	1
>>>>
>>>> 	1 	1 	2 	NULL
>>>>
>>>> 6 	1
>>>>
>>>> 	1 	2 	2 	NULL
>>>>
>>>> 7 	2
>>>>
>>>> 	0 	0 	3 	NULL
>>>>
>>>> 8 	2
>>>>
>>>> 	0 	1 	3 	NULL
>>>>
>>>> 9 	2
>>>>
>>>> 	0 	2 	3 	NULL
>>>>
>>>> I also tried to omit -update -append, but same result.
>>>>
>>>> Versions:
>>>>   * Postgres: "PostgreSQL 12.5 on x86_64-pc-linux-musl, compiled by gcc
>>>>   (Alpine 9.3.0) 9.3.0, 64-bit" * Postgis: "POSTGIS="3.0.3 0" [EXTENSION]
>>>>   PGSQL="120" GEOS="3.8.1-CAPI-1.13.3" PROJ="7.0.1" LIBXML="2.9.10"
>>>>   LIBJSON="0.14" LIBPROTOBUF="1.3.3" WAGYU="0.4.3 (Internal)"" * Gdal:
>>>>   3.2.0
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