Re: Best approach for a "gap-less" sequence

In article <878xlrwcxm(dot)fsf(at)gmail(dot)com>,
Jorge Godoy <jgodoy(at)gmail(dot)com> writes:

> AgentM <agentm(at)themactionfaction(dot)com> writes:
>> Since the gapless numbers are purely for the benefit of the tax people, you
>> could build your db with regular sequences as primary keys and then regularly
>> (or just before tax-time) insert into a table which maps the gapless sequence
>> to the real primary key.

> That's also an interesting approach. An auxiliary table like

> transaction integer FK to the transactions table
> transaction_nb integer gapless sequence

> should do it. A trigger inserting on this auxiliary table would also take
> care of everything... If I have an after trigger I believe I wouldn't need
> any locking... I have to think about this...

Why putting gapless numbers into the database at all? Just calculate them at
query time.