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Unify read and scan functions #13040

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stinodego opened this issue Dec 14, 2023 · 2 comments
Open
3 of 10 tasks

Unify read and scan functions #13040

stinodego opened this issue Dec 14, 2023 · 2 comments
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A-io Area: reading and writing data A-io-cloud Area: reading/writing to cloud storage accepted Ready for implementation enhancement New feature or an improvement of an existing feature
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@stinodego
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stinodego commented Dec 14, 2023

read functions should behave exactly like scan functions followed by collect.

There may be some added or removed parameters for functionality that is (not) relevant in eager mode.

We should take a look at our existing scan functions and make sure they conform to these expectations:

@Wainberg
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Wainberg commented Dec 31, 2023

Here are a few open, unaccepted issues that should be addressed during the harmonization of read_csv and scan_csv:

  • scan_csv() doesn’t support compressed CSVs, read_csv() does: #7287
  • scan_csv() doesn’t support column selection, read_csv() does: #5755
  • scan_csv() doesn’t support BytesIO/StringIO, read_csv() does: #4950, #12617
  • read_csv() doesn’t support reading multiple files, scan_csv() does: #10706

@alexander-beedie alexander-beedie added the A-io Area: reading and writing data label Jan 23, 2024
@mkleinbort-ic
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👍- was about to ask why there is no pl.read_iceberg

On that note - a small documentation recommendation - I think it's time to add sub-headers to the IO functions as grouped by type:

csv: 
- [polars.read_csv](https://docs.pola.rs/py-polars/html/reference/api/polars.read_csv.html)
- [polars.read_csv_batched](https://docs.pola.rs/py-polars/html/reference/api/polars.read_csv_batched.html)
- [polars.scan_csv](https://docs.pola.rs/py-polars/html/reference/api/polars.scan_csv.html)
- [polars.DataFrame.write_csv](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_csv.html)
- [polars.LazyFrame.sink_csv](https://docs.pola.rs/py-polars/html/reference/api/polars.LazyFrame.sink_csv.html)

ipc:
- [polars.read_ipc](https://docs.pola.rs/py-polars/html/reference/api/polars.read_ipc.html)
- [polars.read_ipc_stream](https://docs.pola.rs/py-polars/html/reference/api/polars.read_ipc_stream.html)
- [polars.scan_ipc](https://docs.pola.rs/py-polars/html/reference/api/polars.scan_ipc.html)
- [polars.read_ipc_schema](https://docs.pola.rs/py-polars/html/reference/api/polars.read_ipc_schema.html)
- [polars.DataFrame.write_ipc](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_ipc.html)
- [polars.DataFrame.write_ipc_stream](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_ipc_stream.html)
- [polars.LazyFrame.sink_ipc](https://docs.pola.rs/py-polars/html/reference/api/polars.LazyFrame.sink_ipc.html)

parquet:
- [polars.read_parquet](https://docs.pola.rs/py-polars/html/reference/api/polars.read_parquet.html)
- [polars.scan_parquet](https://docs.pola.rs/py-polars/html/reference/api/polars.scan_parquet.html)
- [polars.read_parquet_schema](https://docs.pola.rs/py-polars/html/reference/api/polars.read_parquet_schema.html)
- [polars.DataFrame.write_parquet](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_parquet.html)
- [polars.LazyFrame.sink_parquet](https://docs.pola.rs/py-polars/html/reference/api/polars.LazyFrame.sink_parquet.html)

database:
- [polars.read_database](https://docs.pola.rs/py-polars/html/reference/api/polars.read_database.html)
- [polars.read_database_uri](https://docs.pola.rs/py-polars/html/reference/api/polars.read_database_uri.html)
- [polars.DataFrame.write_database](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_database.html)

json:
- [polars.read_json](https://docs.pola.rs/py-polars/html/reference/api/polars.read_json.html)
- [polars.read_ndjson](https://docs.pola.rs/py-polars/html/reference/api/polars.read_ndjson.html)
- [polars.scan_ndjson](https://docs.pola.rs/py-polars/html/reference/api/polars.scan_ndjson.html)
- [polars.DataFrame.write_json](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_json.html)
- [polars.DataFrame.write_ndjson](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_ndjson.html)
- [polars.LazyFrame.sink_ndjson](https://docs.pola.rs/py-polars/html/reference/api/polars.LazyFrame.sink_ndjson.html)

avro:
- [polars.read_avro](https://docs.pola.rs/py-polars/html/reference/api/polars.read_avro.html)
- [polars.DataFrame.write_avro](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_avro.html)

excel:
- [polars.read_excel](https://docs.pola.rs/py-polars/html/reference/api/polars.read_excel.html)
- [polars.read_ods](https://docs.pola.rs/py-polars/html/reference/api/polars.read_ods.html)
- [polars.DataFrame.write_excel](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_excel.html#)

iceberg:
- [polars.scan_iceberg](https://docs.pola.rs/py-polars/html/reference/api/polars.scan_iceberg.html)

delta:
- [polars.scan_delta](https://docs.pola.rs/py-polars/html/reference/api/polars.scan_delta.html)
- [polars.read_delta](https://docs.pola.rs/py-polars/html/reference/api/polars.read_delta.html)
- [polars.DataFrame.write_delta](https://docs.pola.rs/py-polars/html/reference/api/polars.DataFrame.write_delta.html)

...

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Labels
A-io Area: reading and writing data A-io-cloud Area: reading/writing to cloud storage accepted Ready for implementation enhancement New feature or an improvement of an existing feature
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