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

Harald Fuchs <hf0731x@protecting.net> writes:

> In article <87zme7uvcn.fsf@gmail.com>,
> Jorge Godoy <jgodoy@gmail.com> writes:
>
>> Harald Fuchs <hf0731x@protecting.net> writes:
>>> Why putting gapless numbers into the database at all?  Just calculate them at
>>> query time.
>
>> And how would you retrieve the record that corresponds to invoice number
>> #16355, for example?  Recalculating few records is fine, but millions of them
>> everytime you need to recover some of those is something that doesn't look
>> efficient to me...
>
> This would be
>
>   SELECT whatever
>   FROM tbl
>   ORDER BY id
>   LIMIT 1
>   OFFSET 16355 -1
>
> Since id is the primary key, this can use an index scan.

If the ID was the number yes.  I thought you were suggesting having the number
computed at "query time", not to insert the record on the table...

--
Jorge Godoy      <jgodoy@gmail.com>