Come on its literally a 2 byte per column header in the row so it just sums the column lengths to get the offset, it does the same thing for fixed length except it gets the col length from the schema.
It's not much more complicated than a fixed length column only the column length is stored in row vs schema. I am not sure where you are getting this idea it way more complicated, nor the 3 vs 4 byte thing, the whole row is a variable length structure and designed as such, null values change the row length fixed or variable data type and have to be accounted for since a null takes up no space in the column data its only in the null bitmap.
> what's the point of user-configuration of someone hard-codes 'NY' in a query or in the code
Because it doesn't matter, 'NY' isn't changing just like 11 the int wouldn't change, but 'NY' is way easier to understand and catch mistakes with and search for code without hitting a bunch of nonsense and distinguish when 10 columns are all coded next to each other in a result set.
I prefer my rows to be a little more readable than 1234, 1, 11, 2, 15, 1 ,3 and the users do too.
I have had my fill of transposition bugs where someone accidentally uses the wrong int on a pk id from a different table and still gets a valid but random result that passes a foreign key check almost enough for me to want to use guid's for pk's almost. At least with the coded values it is easier to spot because even with single character code people tend to pick things that make sense for the column values you know 'P' for pending, 'C' for complete etc, vs 1 2 3 4 used over and over across every different column with an auto increment.
