[gdal-dev] gdal parquet and hive partitioning

[Even Rouault]

Both below issues should now be fixed per 
https://github.com/OSGeo/gdal/pull/13606 .  Turns out what caused GDAL 
to probe all files even when _metadata is present is perhaps completely 
different from the reason for the python reproducer in the below 
apache/arrow issue.

Le 28/12/2025 à 16:48, Even Rouault via gdal-dev a écrit :
>
> Hi Mike,
>
> the problem is likely two folds:
>
> - "gdal vector partition" doesn't write the "_metadata" file that 
> contains the schema and the path to the actual .parquet files
>
> - but even if it did, I cannot manage to convince libarrow/libparquet 
> to not probe all files. Not sure if I'm missing something in the API 
> or if that's a fundamental limitation of the library. I've filed 
> https://github.com/apache/arrow/issues/48671 about that.  I've 
> considered implementing a workaround on GDAL side but I couldn't come 
> with anything.
>
> Your best workaround is to directly access 
> "/vsis3/bucket/overture/20251217/overture-buildings/country=US"
>
> Even
>
> Le 28/12/2025 à 13:26, Michael Smith via gdal-dev a écrit :
>> I know that gdal can write parquet data with hive partitioning using gdal vector partition, but after doing so, can gdal do the partition elimination on reading when a where/attribute is specified on the partition key?
>>
>> I was trying to do a pipeline with:
>> gdal vector pipeline !  read  "/vsis3/bucket/overture/20251217/overture-buildings/” ! filter  --bbox -117.486117584442,33.9156194185775,-117.333055544584,33.9745995301481 --where "country='US'" ! write -f parquet /tmp/test1.parquet --progress --overwrite
>>
>> but in CPL_DEBUG I see it scanning all the partitions rather than just querying the country=US partition.
>>
>> S3: Downloading 0-1605631 (https://bucket.s3.us-east-1.amazonaws.com/overture/20251217/overture-buildings/country%3DAI/data_0.parquet)...
>> S3: Got response_code=206
>> S3: Downloading 0-16383999 (https://bucket.s3.us-east-1.amazonaws.com/overture/20251217/overture-buildings/country%3DAL/data_2.parquet)...
>> S3: Got response_code=206
>> S3: Downloading 0-16383999 (https://bucket.s3.us-east-1.amazonaws.com/overture/20251217/overture-buildings/country%3DAL/data_3.parquet)...
>> S3: Got response_code=206
>> S3: Downloading 16384000-32767999 (https://bucket.s3.us-east-1.amazonaws.com/overture/20251217/overture-buildings/country%3DAL/data_2.parquet)...
>> S3: Got response_code=206
>> S3: Downloading 16384000-29741378 (https://bucket.s3.us-east-1.amazonaws.com/overture/20251217/overture-buildings/country%3DAL/data_3.parquet)...
>> ....
>>
>>
>>
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>
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