Re: hot to determine calculated fields (views)

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От will trillich
Тема Re: hot to determine calculated fields (views)
Дата
Msg-id 20030127064219.GE6171@mail.serensoft.com
обсуждение исходный текст
Ответ на Re: hot to determine calculated fields (views)  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-general
On Sat, Jan 25, 2003 at 11:50:42AM -0500, Tom Lane wrote:
> will trillich <will@serensoft.com> writes:
> > how can i tell whether i'm looking at a computed field (from a
> > view) as opposed to actual data (brought in directly from a
> > table)? something in pg_attribute, i hope... :)
>
> You mean, how to tell which columns of a view are just "select foo from..."
> and which are more complex expressions?
>
> AFAICS, the only way is to parse the view definition rule.  The system
> won't give you any help on this, because it neither knows nor cares...

so there's no difference in the defined relation (table) between
these two--

    create table first (
        i int,
        j int,
        t text,
        x text
    );

and

    create view last as
    select
                         i,
        i * j         as j,
                         t,
        substr(x,i,j) as x
    from first
    ;

? no flags at all, stored anywhere?

pooh.

--
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