Function polars::prelude::count_rows_from_slice

pub fn count_rows_from_slice(
    bytes: &[u8],
    separator: u8,
    quote_char: Option<u8>,
    comment_prefix: Option<&CommentPrefix>,
    eol_char: u8,
    has_header: bool,
) -> Result<usize, PolarsError>

Available on crate feature polars-io only.

Read the number of rows without parsing columns useful for count(*) queries