Re: [HACKERS] create table and default 'now' problem ? - Mailing list pgsql-hackers

Thank you Tom for explanation. It's not very bothered me as far as I have
many workarounds suggested in mailing list. But I wondering because
'now'::text works as expected when I create view

create view www_auth as select  a.account as user_name, a.password, b.nick as      group_name           from users a,
resourcesb, privilege_user_map c           where a.auth_id = c.auth_id and b.res_id = c.res_id and
(a.account_valid_untilis null or                 a.account_valid_until > datetime('now'::text)) and
c.perm_id= 1;
 
Regards,    Oleg

On Tue, 21 Sep 1999, Tom Lane wrote:

> Date: Tue, 21 Sep 1999 09:40:40 -0400
> From: Tom Lane <tgl@sss.pgh.pa.us>
> To: Oleg Bartunov <oleg@sai.msu.su>
> Cc: Thomas Lockhart <lockhart@alumni.caltech.edu>,
>     pgsql-hackers@postgreSQL.org
> Subject: Re: [HACKERS] create table and default 'now' problem ? 
> 
> >>>>>> how I could create table with datetime field default
> >>>>>> to 'now'::text in a way Jan did in his shoes rule example ?
> 
> A couple of comments on this thread:
> 
> 1.  Seems to me that the easy, reliable way is just to use the
> now() function --- you don't have to make one, it's built in:
> 
>     create table test ( a datetime default now(), b int);
> 
> This avoids all the issues about when constants get coerced, and
> probably ought to be what we recommend to newbies.  However,
> this is certainly a workaround for an existing bug.
> 
> 2.  I believe that most of the problem with premature constant coercion
> in default values is coming from the bizarre way that default values get
> entered into the database.  StoreAttrDefault essentially converts the
> parsed default-value tree back to text, constructs a SELECT statement
> using the text, parses that, and examines the resulting parsetree.
> Yech.  If it were done carefully it might work, but it's not; the
> reverse parser does not do quoting carefully, does not do type coercion
> carefully, and fails to handle large parts of the expression syntax at
> all.  (I've ranted about this before ... check the pghackers archives.)
> 
> I have a to-do list item to rip all that code out and do it over again
> right.  Might or might not get to it for 6.6 --- does someone else want
> to tackle it?
> 
> 3.  Yes, this is a bug too:
> 
> >> create table test ( a datetime default 'now'::text,...)
> > Parser complains:
> > ERROR:  parser: parse error at or near "'"
> > Does this considered as a bug or feature ?
> 
> See above --- reverse-parsing of this construct is wrong.  I have
> no intention of fixing the reverse parser; I want to get rid of it
> entirely.
> 
>             regards, tom lane
> 

_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83