> if I do a group by over all rows in a table that they may not perform better Computing aggregates against contiguous values in memory or disk for a single co

> if I do a group by over all rows in a table that they may not perform better Computing aggregates against contiguous values in memory or disk for a single column will always be faster than reading records with differing value offsets/alignments. These operations can benefit from SIMD and other hardware optimizations you don't get with row-aligned data.