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()'. -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com Only you can decide what is important to you.
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml index f19306e7760..4d47248fccf 100644 --- a/doc/src/sgml/ref/create_table.sgml +++ b/doc/src/sgml/ref/create_table.sgml @@ -888,6 +888,13 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM match the data type of the column. </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> + <para> The default expression will be used in any insert operation that does not specify a value for the column. If there is no default