On Fri, Jul 5, 2024 at 05:11:22PM -0400, Bruce Momjian wrote:
> On Fri, Jul 5, 2024 at 05:03:35PM -0400, Tom Lane wrote:
> > Bruce Momjian <br...@momjian.us> writes:
> > > Well, 'now()' certainly _looks_ like a function call, though it isn't.
> > > The fact that 'now()'::timestamptz and 'now'::timestamptz generate
> > > volatile results via a function call was my point.
> >
> > The only reason 'now()'::timestamptz works is that timestamptz_in
> > ignores irrelevant punctuation (or what it thinks is irrelevant,
> > anyway). I do not think we should include examples that look like
> > that, because it will further confuse readers who don't already
> > have a solid grasp of how this works.
>
> Wow, I see that now:
>
> test=> SELECT 'now('::timestamptz;
> timestamptz
> -------------------------------
> 2024-07-05 17:04:33.457915-04
>
> If I remove the 'now()' mention in the docs, patch attached, I am
> concerned people will be confused whether it is the removal of the
> single quotes or the use of "()" which causes insert-time evaluation,
> and they might try 'now()'.
Does anyone like this patch? I changed now()::timestamptz to
now::timestamptz.
--
Bruce Momjian <br...@momjian.us> https://momjian.us
EDB https://enterprisedb.com
When a patient asks the doctor, "Am I going to die?", he means
"Am I going to die soon?"
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index 83859bac76f..f5b861b387f 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -897,6 +897,13 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
does not specify a value for the column. If there is no default
for a column, then the default is null.
</para>
+
+ <para>
+ Note, a string that returns a volatile result once cast to a data
+ type, like <literal>'now'::timestamptz</literal>, is evaluated at
+ table creation time, while <literal>now::timestamptz</literal>
+ (without quotes) is evaluated at data insertion time.
+ </para>
</listitem>
</varlistentry>
