[gdal-dev] Streaming Parser for OGR GeoJSON Driver

[Even Rouault]

> 
> Perhaps it works because I am only appending to a single layer that has the
> same schema throughout?

Yes

> I did test this, but the performance was indeed slower. Is there a way for
> me to specify the schema before-hand and avoid a full first pass?
> 
> Perhaps for a driver implementation with a streaming parser, I could write
> a vrt before hand, then pipe in GeoJSON that matches that schema?

Yes, if you know the fields, you can do something like:

<OGRVRTDataSource>
  <OGRVRTUnionLayer>
    <OGRVRTLayer name="OGRGeoJSON">
        <SrcDataSource>tmp1.json</SrcDataSource>
    </OGRVRTLayer>
    <OGRVRTLayer name="OGRGeoJSON">
        <SrcDataSource>tmp2.json</SrcDataSource>
    </OGRVRTLayer>
    <Field name="..." type="..."/>
...
    <Field name="..." type="..."/>
  </OGRVRTUnionLayer>
</OGRVRTDataSource>

And if you don't know them but are OK to take the one of the first sources (so 
your current strategy) :

<OGRVRTDataSource>
  <OGRVRTUnionLayer>
    <OGRVRTLayer name="OGRGeoJSON">
        <SrcDataSource>tmp1.json</SrcDataSource>
    </OGRVRTLayer>
    <OGRVRTLayer name="OGRGeoJSON">
        <SrcDataSource>tmp2.json</SrcDataSource>
    </OGRVRTLayer>
    <FieldStrategy>FirstLayer</FieldStrategy>
  </OGRVRTUnionLayer>
</OGRVRTDataSource>

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