Re: pg_system_identifier()

Dne 17. 9. 2013 17:01 "Andres Freund" <andres(at)2ndquadrant(dot)com> napsal(a):
>
> On 2013-09-17 10:57:46 -0400, Robert Haas wrote:
> > On Mon, Sep 16, 2013 at 1:25 AM, Satoshi Nagayasu <snaga(at)uptime(dot)jp>
wrote:
> > > How about adding new system view with new function which returns
> > > a single pg_controldata value in text type, and using a cast for
> > > each column in the view definition?
> > >
> > > CREATE VIEW pg_catalog.pg_controldata AS
> > > SELECT pg_controldata('control_version')::integer AS
control_version,
> > > pg_controldata('catalog_version')::integer AS
catalog_version,
> > > pg_controldata('system_identifier')::bigint AS
system_identifier,
> > > ...
> > > pg_controldata('next_xlog_file')::char(25) AS next_xlog_file,
> > > ...
> > > pg_controldata('encoding')::text AS encoding;
> > >
> > > Given that the view can work like a SRF, and it allows us to retrieve
> > > all the values of pg_controldata with appropriate types in single
> > > record from the view:
> >
> > I like this idea. I think having an easy way to get the values with
> > the right types will be a plus. But adding a separate function for
> > each field seems excessive, so I think this is a good compromise.
>
> Why not add a single function returning a composite type then? That'd at
> least have a chance of returning consistent values for the individual
> values that change during runtime. It would also produce proper errors
> when you load a view using columns that don't exist anymore instead of
> just at runtime.
>

+1

Pavel

> Greetings,
>
> Andres Freund
>
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> Andres Freund http://www.2ndQuadrant.com/
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