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

[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
>