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Add function to infer schema from files(CSV/Parquet) #6345

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BohuTANG opened this issue Jun 30, 2022 · 3 comments
Closed

Add function to infer schema from files(CSV/Parquet) #6345

BohuTANG opened this issue Jun 30, 2022 · 3 comments
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C-feature Category: feature good first issue Category: good first issue

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@BohuTANG
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BohuTANG commented Jun 30, 2022

Summary

As arrow2 has infer_schema:
Parquet:
https://github.com/jorgecarleitao/arrow2/blob/5725fa3c18830f88ed0ed67067dda5c1d2080dca/src/io/parquet/read/schema/mod.rs#L23-L31

CSV:
https://github.com/jorgecarleitao/arrow2/blob/79b87b629d8fdc3fa40b5ad7abc3889c5102a52b/src/io/csv/read/infer_schema.rs#L15

We can add a function INFER_SCHEMA to do the schema infer, syntax like:

INFER_SCHEMA(
LOCATION => '{ internalStage | externalStage }'
  , FILE_FORMAT => '<format_name>'
)

example(from snow):

select * from infer_schema(location=>'@mystage/geography/cities.parquet' , file_format=>'parquet')


+-------------+---------+----------+---------------------+--------------------------+
| COLUMN_NAME | TYPE    | NULLABLE | EXPRESSION          | FILENAMES                |
|-------------+---------+----------+---------------------+--------------------------|
| continent   | TEXT    | True     | $1:continent::TEXT  | geography/cities.parquet |
| country     | VARIANT | True     | $1:country::VARIANT | geography/cities.parquet |
+-------------+---------+----------+---------------------+--------------------------+

Reference:
https://docs.snowflake.com/en/sql-reference/functions/infer_schema.html

@BohuTANG BohuTANG added the C-feature Category: feature label Jun 30, 2022
@BohuTANG
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cc @Xuanwo

@Xuanwo Xuanwo self-assigned this Jun 30, 2022
@BohuTANG BohuTANG added the good first issue Category: good first issue label Jul 21, 2022
@Xuanwo Xuanwo self-assigned this Sep 16, 2022
@Xuanwo
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Xuanwo commented Sep 16, 2022

I'm taking this issue now.

@Xuanwo
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Xuanwo commented Nov 3, 2023

Already implemented by @youngsofun

@Xuanwo Xuanwo closed this as completed Nov 3, 2023
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Labels
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