[twhitmore]

In datamodelling, tables can often be categorized by lifetime. 'Business Relationships' eg. customers, suppliers, products have a fairly long lifetime; whereas 'Business Transactions' are created on a much higher frequency.

I'm generally fairly comfortable using int for business relationships, and bigint (long) for transaction data.

For performance, insertion speed often seems to be dominated by 'commit latency' to sync to the disk; rather than by record size. I would agree that record size affects table scan, but for many datamodels keying may often be a relatively small proportion compared to the size of text fields and other data.

I like to model keyspaces to work for 200 years, for the largest forseeable market growth, times at least a factor of 10 for safety.