Re: pervasiveness of surrogate (also called synthetic) keys

2011/5/4 Merlin Moncure <mmoncure(at)gmail(dot)com>

> Most of the old school accounting systems maintained an invoice line
> number.
>
> > Invoice Line
> > -Invoice Number
> > -LineNo
> > -ItemID
> > -qty
> > -Price
>
> The line number started from 1 (the first line on the invoice) on
> every unique invoice. This has the added benefit of allowing the
> primary key index (invoice_no, line_no) allowing you to pull up the
> invoice line records in correct order without requiring an extra sort
> and, if you don't need any fields from the invoice, a join.
>
> Compare the two queries pulling up invoice lines over a range of
> invoice numbers.
>
> merlin
>

Thanks, merlin,

And in that case, what is "Natural" in LineNo? I would say, with adding
LineNo we are creating syntethic/surrogate Key (just instead of 1 surrogate
column - it will be Compound key with more columns...)? The same is with all
other tables what are "parts" of an Entity, Serial Numbers, Accounting
Distribution produced by Invoice...etc etc...