> each document size is ~1GB instead of ~20MB. Where's that 50x multiplier coming from? We've already established that the worst case difference here is 4x, and that only in the case where all values are single-digit integers. > what is the point to talk about cost of storage? If you spend $1000 in developer time to save $50 in storage, you've wasted someone's money. (Which is why this is probably my last message in this thread: time to move on to something more productive.) > the database is holding extra two integers Yes, two 64-bit ints and a 64-bit float per datum = 24 bytes, vs. strings like "1.2345," 8 ASCII characters for 4-decimal digit precision, giving a 3:1 size difference in this case, while running faster because it isn't doing all this ASCII string manipulation. TANSTAAFL.