> I am not asking how the code works. That's precisely what you asked for before: "plain language" explanation of the code. > I am asking why it makes sense when length(sqlar.blob)==sqlar.sz, there is no compression, when length(sqlar.blob)<sqlar.sz there is compression? My previous response answers that. sqlar will *never* produce compressed data which is the same size or larger than the original. If compression (including the header) would be the same size or larger than the original, the compressed results are discarded and the original data is used in its place.