BufferedData compares staging memory bytes with a row-count threshold

[zuston]

Description

BufferedData::add_batch uses compute_suggested_batch_size_for_output to determine when staged record batches should be sorted and flushed.

However, compute_suggested_batch_size_for_output(mem_size, num_rows) returns a suggested number of rows, while the current condition compares that value with staging_mem_used, which is measured in bytes:

let suggested_batch_size =
    compute_suggested_batch_size_for_output(
        self.staging_mem_used,
        self.staging_num_rows,
    );

if self.staging_mem_used > suggested_batch_size {
    self.flush_staging()?;
}