Function read_column 

fn read_column<T: DataType>(
    row_group: &dyn RowGroupReader,
    index: usize,
) -> Result<Vec<T::T>>

Reads every value of one column in a row group.

Records are read in batches of up to the row group’s row count until the reader returns none. The columns are REQUIRED, so no definition or repetition levels are requested.

Arguments

• row_group - Row group to read from.
• index - Column index (0 for timestamp_unix_ns, 1 for value).

Returns

The column’s values in file order.

Errors

Returns an error if the column reader cannot be created or a page cannot be read or decoded.

Panics

Panics if the physical type of column index does not match T.