Make Parquet writer nullable option application to single table writes
#12933
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…pq-single-write-force-nullable
…pq-single-write-force-nullable
vuule
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vuule
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nullability option application to single table writesnullable option application to single table writes
robertmaynard
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Mar 15, 2023
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bdice
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Mar 15, 2023
ttnghia
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Mar 15, 2023
The Parquet writer used to throw when called with the |
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/merge |
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Requires: #12933 This PR adds `nullability` parameter to parquet writer. When it is `True`, all columns are written as `null` in the schema. When `False`, all columns are written as `not null` in the schema, however, if a column contains null values, this parameter is ignored. Authors: - GALI PREM SAGAR (https://github.com/galipremsagar) - Vukasin Milovanovic (https://github.com/vuule) Approvers: - Vukasin Milovanovic (https://github.com/vuule) - Bradley Dice (https://github.com/bdice) URL: #12952
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Description
When writing multiple tables into a single Parquet file, users can run into issues if a column does not have nulls in the first table, but have some in other tables. The
nullablemember ofcolumn_in_metadatawas originally added to address this and allow users to enforce nullability of columns from multiple tables. Because of this, thenullableoption is only applied to chunked writes.Recently, a different use for the option has been identified, where tables are stored into individual Parquet files, which are later read and the read tables are concatenated. Without the option to enforce nullability, Parquet files can end up with different nullabilities, i.e. different schemas, causing concatenation to fail.
This PR allows the nullable option to apply to single writes as well. The write call throws if user tried to write a column with nulls as non-nullable.
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