Data engineering·Files, formats and table layers
the file is split into blocks of a hundred and twenty-eight megabytes, each with its own min and max per column.
Row group
Also calledstripe, chunk
The unit of horizontal partitioning inside a columnar file, holding a range of rows across all columns along with per-column statistics. It is the unit of skipping and the unit of parallelism, so its size sets both how precisely a reader can avoid data and how evenly work spreads. Very small row groups defeat the statistics and add overhead; very large ones mean reading far more than the query needed.