> i have to store a dataset of 20 elements. the data is a int(1).
> i would have about 800 000 datasets. now the question is what performs better
> with mysql?
> is it better to have 800 000 rows with 21 columns or 160 000 000 rows
> with 3 columns?
That's 16M rows, not 160M rows, and using INT(1) makes little sense
when you can save 3 bytes per value by using TINYINT(1). Anyway,
I don't think I can answer your question without knowing more about
what you'll do with your data. If the 20 numbers in a set will be
representing different things, it makes sense to have 20 columns
to save space and time, but if you're going to e.g. search for
all sets that have a member greater than x, it's a pain to handle.
Normally, though, I think that having 20 columns is a better way
to do it, if you're going to treat those 20 values as one set,
which always has the same number of members (20).
Carl Troein - C carl@stripped | http://pixelmagic.dyndns.org/~cirdan/
Amiga user since '89, and damned proud of it too.