Re: sequences what does ::text mean ?

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От Josh Jore
Тема Re: sequences what does ::text mean ?
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Msg-id Pine.BSO.4.44.0207030807260.30576-100000@kitten.greentechnologist.org
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Ответ на Re: sequences what does ::text mean ?  (Andrew McMillan <andrew@catalyst.net.nz>)
Ответы Re: sequences what does ::text mean ?  (Tom Lane <tgl@sss.pgh.pa.us>)
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See and here thought that if you can specify a datatype then you
circumvent a type resolution or two. My understanding (which was largely
guessing after watching Josh Berkus) was that the atom 'seq_auteurs' is
considered to be of unknown type until it is needed for evaluation in an
expression. During evaluation the value is coerced into something more
specific. My thought was that if the value is pre-coerced then that saves
a run-time step.

Joshua b. Jore ; http://www.greentechnologist.org

On 3 Jul 2002, Andrew McMillan wrote:

> On Wed, 2002-07-03 at 22:05, Ewald Geschwinde wrote:
> > Henk Schets wrote:
> >
> > >Hi,
> > >
> > >In a table I have as a default value nextval('seq_auteurs').  What's the difference with
nextval('seq_auteurs'::text)? 
> > >
> > >Henk
> > >
> > >
> > >
> > >---------------------------(end of broadcast)---------------------------
> > >TIP 4: Don't 'kill -9' the postmaster
> > >
> > >
> > >
> > >
> > >
> > The difference ist nextval('seq_autheurs') you get an integer back and
> > with the second one it casts the integer to text and returns a text value
>
> No you won't - that ::text is _inside_ the brackets.  You'll still get
> an INT4.
>
> There really is no difference.  I think the second might be the somewhat
> pedantic output of pg_dump.
>
> Regards,
>                     Andrew.
> --
> --------------------------------------------------------------------
> Andrew @ Catalyst .Net.NZ Ltd, PO Box 11-053, Manners St, Wellington
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>
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