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 <br...@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
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>
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