mysql - Creating rows vs. columns performance

Question

I built an analytics engine that pulls 50-100 rows of raw data from my database (lets call it raw_table), runs a bunch statistical measurements on it in PHP and

Answer 1

I think the advantage to storing as more rows (i.e. normalized) depends on design and maintenance considerations in the face of change.

Also, if the 140 columns have the same meaning or if it differs per experiment - properly modeling the data according to normalization rules - i.e. how is data related to a candidate key.

As far as performance, if all the columns are used it makes very little difference. Sometimes a pivot/unpivot operation can be expensive over a large amount of data, but it makes little difference on a single key access pattern. Sometimes a pivot in the database can make your frontend code a lot simpler and backend code more flexible in the face of change.

If you have a lot of NULLs, it might be possible to eliminate rows in a normalized design and this would save space. I don't know if MySQL has support for a sparse table concept, which could come into play there.