[gdal-dev] gdal parquet and hive partitioning

[Michael Smith]

Wow, very cool. Yeah the source had been written with duckdb so I believe the metadata is present. 

 

I’ll check out master once this is merged.

 

Thanks so much!

 

Mike

 

-- 

Michael Smith

RSGIS Center – ERDC CRREL NH

US Army Corps

 

 

From: gdal-dev <gdal-dev-bounces at lists.osgeo.org> on behalf of Even Rouault via gdal-dev <gdal-dev at lists.osgeo.org>
Reply-To: Even Rouault <even.rouault at spatialys.com>
Date: Sunday, December 28, 2025 at 6:56 PM
To: <gdal-dev at lists.osgeo.org>
Subject: Re: [gdal-dev] gdal parquet and hive partitioning

 

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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http://www.spatialys.com
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