Alain wrote:

you are saying that zip ratio is somewhat related to normalized data, interesting view, and certainly true :)

I find it a nice heuristic to help me get started. Just sort the tables on size, start compressing them and start with ones compressing best.

About DateTimes, I think this is not different than with other values, using a pointer to an interned value should be equivalent to using an int, as it would be a 32 bits pointer, and with this approach, using compact records should not make a big difference too if there is not a lot of different values.

Combining multiple booleans in one word still helps a lot, and introducing extra objects for highly correlated fields.

The key I mentioned here is that in real life, this "normalizing ratio" is very high for almost every kind of data and that's what puzzles me (not the technique).

My impression is that the a lot of the design decisions for relational databases are cargo cult based on the time where most database did not fit into ram and the query optimizers were not good at dealing with lots of joins. Stephan