[gdal-dev] Does OAPIF paging work as supposed?

Rahkonen Jukka (MML) jukka.rahkonen at maanmittauslaitos.fi
Mon Sep 27 06:21:31 PDT 2021


I tried to read a relatively small BBOX from an OAPIF server but the process feels rather slow and I do not quite understand what I am seeing in the log.

ogr2ogr -f GPKG test.gpkg OAPIF:https://avoin-paikkatieto.maanmittauslaitos.fi/maastotiedot/features/v1/?api-key=xxxx -spat 25 65 25.1 65.1 -oo PAGE_SIZE=10000 --debug on --config cpl_curl_verbose yes

Excerpts from the log:

HTTP: Fetch(https://avoin-paikkatieto.maanmittauslaitos.fi/maastotiedot/features/v1/collections/osoitepiste/items?api-key=xxxx&f=json&limit=10000)
HTTP: These HTTP headers were set: Accept: application/geo+json, application/json
> GET /maastotiedot/features/v1/collections/osoitepiste/items?api-key=xxxx&f=json&limit=10000 HTTP/1.1
Host: avoin-paikkatieto.maanmittauslaitos.fi
Accept-Encoding: gzip
Accept: application/geo+json, application/json

* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
GeoJSON: First pass: 56.54 %
GeoJSON: First pass: 100.00 %
HTTP: Fetch(https://avoin-paikkatieto.maanmittauslaitos.fi/maastotiedot/features/v1/collections/osoitepiste/items?api-key=xxxx&f=json&limit=10000&bbox=25,65,25.1000000000000014,65.0999999999999943)
> GET /maastotiedot/features/v1/collections/osoitepiste/items?api-key=xxxx&f=json&limit=10000&bbox=25,65,25.1000000000000014,65.0999999999999943 HTTP/1.1
< Content-Length: 309
GDALVectorTranslate: 0 features written in layer 'osoitepiste'

Do I read right that GDAL is first reading one page, in this time 10000 features without BBOX, perhaps for resolving the schema, and then makes a new query with BBOX? In this case the BBOX query finds nothing. Reading 10000 features on the first round and then discarding everything feels too expensive. Could it be enough to read for example 10 features that is the default page size on the first round instead of the full page?

-Jukka Rahkonen-
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