Fixed-width text

The fwf driver splits text rows into fixed-width columns and queries them with Polars SQL.

URL format

fwf://<file>?widths=<widths>[&headers=<names>]

Options

Option	Behavior / default
`widths`	Required comma-separated field widths, such as `5,20,3`. Widths are measured in bytes.
`headers`	Comma-separated column names. The number must match `widths`; defaults to `A`, `B`, `C`, and so on.

Examples

rsql --url 'fwf://people.fwf?widths=5,20,3&headers=id,name,age' -- 'SELECT * FROM people;'

Usage notes

Every line is treated as data. Fields are trimmed and imported as strings; cast columns in SQL when needed. Rows shorter than the configured widths fail to load. There are no has_header or skip_rows options.

The file is loaded into an in-memory Polars SQL context. Its table name is the filename before the first dot: people.csv becomes people. Use .tables and .describe people to inspect the imported data. Query results and session changes do not write back to the source file.