On Sunday, October 21, 2012 07:24:52 PM Andrew Dunstan wrote:
> On 10/21/2012 12:36 PM, Andres Freund wrote:
> > On Sunday, October 21, 2012 06:30:14 PM Andrew Dunstan wrote:
> >> On 10/21/2012 12:20 PM, Abhijit Menon-Sen wrote:
> >>> At 2012-10-21 11:49:26 -0400, cbbro...@gmail.com wrote:
> >>>> If there is a natural sequence (e.g. - a value assigned by nextval()),
> >>>> that offers a natural place to apply the usual order-imposing ORDER BY
> >>>> that we are expected to use elsewhere.
> >>> 
> >>> Note: "INSERT … RETURNING" doesn't accept an ORDER BY clause.
> >> 
> >> No, but you can wrap the INSERT .. RETURNING in a CTE and order that.
> > 
> > Personally I find that a not very practical suggestion. It means you need
> > the ability to sort the data equivalently on the clientside which isn't
> > always easy if you consider platform/locale and whatever differences.
> 
> Er, what?
> 
>     with orig_inserts as
>     (
>          insert into table_1
>          ...
>          returning *
>     ),
>     ordered_inserts as
>     (
>          select * from orig_inserts
>          order by ...
>     )
>     insert into table_2
>     select * from ordered_inserts ...;

I am not sure I get the point of this.

> why does the client have to be involved, exactly?

Suppose you have something like

CREATE TABLE positionlog(
id serial primary key,
timestamp timestamptz DEFAULT NOW(),
position geometry
);

And you want to insert multiple values in one roundtrip *and* know their ids 
in your application.

INSERT INTO positionlog(position)
VALUES
    ('POINT(..., ...)'),
    ('POINT(..., ...)')
RETURNING id, timestamp, position
;

If you want to correlate re returned ids with data in your application without 
relying on the ordering of INSERT ... VALUES... RETURNING you would need to 
sort a postgis type in the same way the server does it.
Am I missing something here?

Greetings,

Andres

-- 
Andres Freund           http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services


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