I have a similar issue with trying to read huge 1GB parquet files from Azure DataLake Storage. I'm trying to read the file in small chunks using the ParquetFile.iter_batches method, but it seems like the entire file is read into memory before the first batch is returned. I am using the Azure SDK for python and another python package (pyarrowfs-adlgen2). Has anyone faced a problem similar to what I am seeing, or is there a workaround?
On Fri, Dec 24, 2021 at 2:11 PM Cindy McMullen <[email protected]> wrote: > Thanks, Arthur, this helps. The complete code example is: > > filename = 'gs://' + files[0] > gs = gcsfs.GCSFileSystem() > f = gs.open(filename) > pqf = pq.ParquetFile(f) > pqf.metadata > > > On Thu, Dec 23, 2021 at 1:48 AM Arthur Andres <[email protected]> > wrote: > >> Hi Cindy, >> >> In your case you'd have to pass a GCS file instance to the ParquetFile >> constructor. Something like this: >> >> source = fs.open_input_file(filename) >> parquet_file = pq.ParquetFile(source) >> >> You can see how read_table does this in the source code: >> https://github.com/apache/arrow/blob/16c442a03e2cf9c7748f0fa67b6694dbeb287fad/python/pyarrow/parquet.py#L1977 >> >> I hope this helps. >> >> >> >> On Thu, 23 Dec 2021 at 05:17, Cindy McMullen <[email protected]> >> wrote: >> >>> Hi - >>> >>> I need to drop down to the ParquetFile API so I can have better control >>> over batch size for reading huge Parquet files. The filename is: >>> >>> >>> *gs://graph_infra_steel_thread/output_pq/parquet/usersims/output-20211202-220329-20211202-220329-00-0012.parquet.snappy* >>> >>> This invocation fails: >>> *pqf = pq.ParquetFile(filename)* >>> "FileNotFoundError: [Errno 2] Failed to open local file >>> 'gs://graph_infra_steel_thread/output_pq/parquet/usersims/output-20211202-220329-20211202-220329-00-0012.parquet.snappy'. >>> Detail: [errno 2] No such file or directory" >>> >>> While this API, using the same, succeeds because I can specify 'gs' >>> filesystem. >>> *table = pq.read_table(filename, filesystem=gs, >>> use_legacy_dataset=False) * >>> >>> I don't see a way to specify 'filesystem' on the ParquetFile API >>> <https://arrow.apache.org/docs/python/generated/pyarrow.parquet.ParquetFile.html#pyarrow.parquet.ParquetFile>. >>> Is there any way to read a GCS file using ParquetFile? >>> >>> If not, can you show me the code for reading batches using pq.read_table >>> or one of the other Arrow Parquet APIs >>> <https://arrow.apache.org/docs/python/api/formats.html#parquet-files>? >>> >>> Thanks - >>> >>> -- Cindy >>> >> -- Partha Dutta [email protected]
