davlee1972 opened a new issue, #38518:
URL: https://github.com/apache/arrow/issues/38518
### Describe the enhancement requested
For all dataset/scanner functions like to_table(), head(), etc.. which
support @columns..
This works..
`to_table(columns=["my_column", "__filename"])`
But built-in columns are not supported using expressions:
`to_table(columns = {"my_column": ds.field("my_column") , "filename":
ds.field("__filename")})`
I'm trying to create an expressions to parse out YYYYMMDD from the following
filename:
VAR_pnl.20230829.csv.gz
But I need to be able to reference the built-in column "__filename" in the
expression..
My only other option is to extract everything into memory first using
@columns= ["a","b", "__filename"], but this isn't ideal for memory management.
### Component(s)
Python
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