Date: Sat, 25 Jan 2014 14:33:21 -0500
From: Bruce Momjian <bruce@momjian.us>
To: David Johnston <polobo@yahoo.com>
Cc: pgsql-docs@postgresql.org
Subject: Re: Create Table ... Like Including Default & Sequences
Message-ID: <20140125193321.GB9750@momjian.us>
References: <1371176405220-5759108.post@n5.nabble.com>
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="mYCpIKhGyMATD0i+"
Content-Disposition: inline
In-Reply-To: <1371176405220-5759108.post@n5.nabble.com>
User-Agent: Mutt/1.5.20 (2009-06-14)
Precedence: bulk
Sender: pgsql-docs-owner@postgresql.org


--mYCpIKhGyMATD0i+
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

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@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +

--mYCpIKhGyMATD0i+
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="like.diff"

diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
new file mode 100644
index a422edd..e0b8a4e
*** a/doc/src/sgml/ref/create_table.sgml
--- b/doc/src/sgml/ref/create_table.sgml
*************** CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY
*** 329,335 ****
       </para>
       <para>
        Default expressions for the copied column definitions will only be
!       copied if <literal>INCLUDING DEFAULTS</literal> is specified.  The
        default behavior is to exclude default expressions, resulting in the
        copied columns in the new table having null defaults.
       </para>
--- 329,338 ----
       </para>
       <para>
        Default expressions for the copied column definitions will only be
!       copied if <literal>INCLUDING DEFAULTS</literal> is specified. 
!       Defaults that call database-modification functions, like
!       <function>nextval</>, create a linkage between the original and
!       new tables.  The
        default behavior is to exclude default expressions, resulting in the
        copied columns in the new table having null defaults.
       </para>

--mYCpIKhGyMATD0i+
Content-Type: text/plain
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
MIME-Version: 1.0


-- 
Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-docs

--mYCpIKhGyMATD0i+--