Re: Create Table ... Like Including Default & Sequences

On Thu, Jun 13, 2013 at 07:20:05PM -0700, David Johnston wrote:
> In the documentation for "Create Table" the following paragraph appears under
> the definition for LIKE:
>
> "Default expressions for the copied column definitions will only be copied
> if INCLUDING DEFAULTS is specified. The default behavior is to exclude
> default expressions, resulting in the copied columns in the new table having
> null defaults."
>
> I would like to suggest adding a sentence between the first and second:
>
> Defaults created via the "serial" and "bigserial" construct - or that use
> "nextval(...)" generally - are copied as-is resulting in both tables sharing
> the same underlying sequence.
>
> Note that this is technically contrary to the statement:
>
> Unlike INHERITS, the new table and original table are completely decoupled
> after creation is complete.
>
> I'm working in 9.0 and noticed this incidentally when a FK constraint failed
> but the expected ID was somewhere in the 10s while the actual was somewhere
> upward of 80,000 which clued me into the fact that the original sequence was
> being used.
>
> As an aside it may be worth noting (or linking to) a quick way to change the
> default on the new table if this is done in error and a correction is
> desired. For my purposes I'll likely just leave it alone.

Oh, that is something I had not considered. I have applied the attached
doc patch for 9.4.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ Everyone has their own god. +