delayed input

[Hicham G. Elmongui]

I need to select all tuples from a table, but need them to be fetched with a
constant delay (say 1 sec) between every consecutive tuples.

The first idea that came up to my mind is to create a DelayedSeqScan
operator, and put delay before returning the scanned tuple.

Can I do this functionality using table functions?

Regards,
--h

[Kevin Barnard]

Re: delayed input

Why not do this on the client side? I'm just curious as to the benfit
of doing this on the server.

On Tue, 19 Oct 2004 11:10:58 -0500, Hicham G. Elmongui
<elmongui@cs.pu rdue.edu> wrote:[color=blue]
> I need to select all tuples from a table, but need them to be fetched with a
> constant delay (say 1 sec) between every consecutive tuples.
>
> The first idea that came up to my mind is to create a DelayedSeqScan
> operator, and put delay before returning the scanned tuple.
>
> Can I do this functionality using table functions?
>
> Regards,
> --h[/color]

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[Richard Huxton]

Re: delayed input

Hicham G. Elmongui wrote:[color=blue]
> I need to select all tuples from a table, but need them to be fetched with a
> constant delay (say 1 sec) between every consecutive tuples.
>
> The first idea that came up to my mind is to create a DelayedSeqScan
> operator, and put delay before returning the scanned tuple.
>
> Can I do this functionality using table functions?[/color]

Could you not just use a cursor and fetch each row in turn based on some
timer in your application?

--
Richard Huxton
Archonet Ltd

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[Pierre-Frédéric Caillaud]

Re: delayed input



Use a cursor...
[color=blue]
> I need to select all tuples from a table, but need them to be fetched
> with a
> constant delay (say 1 sec) between every consecutive tuples.
>
> The first idea that came up to my mind is to create a DelayedSeqScan
> operator, and put delay before returning the scanned tuple.
>
> Can I do this functionality using table functions?
>
> Regards,
> --h
>
>
>
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> TIP 5: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/docs/faqs/FAQ.html
>[/color]



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[Hicham G. Elmongui]

Re: delayed input

I need this for a side project. Is there a way to do something like this:

SELECT *
FROM DelayedTable('t ablename', 5);

DelayedTable provides me with one tuple every 5 seconds.
Regards,
--h

"Hicham G. Elmongui" <elmongui@cs.pu rdue.edu> wrote in message
news:cl3eaj$1gg v$1@news.hub.or g...[color=blue]
> I need to select all tuples from a table, but need them to be fetched with[/color]
a[color=blue]
> constant delay (say 1 sec) between every consecutive tuples.
>
> The first idea that came up to my mind is to create a DelayedSeqScan
> operator, and put delay before returning the scanned tuple.
>
> Can I do this functionality using table functions?
>
> Regards,
> --h
>
>[/color]

[Gaetano Mendola]

Re: delayed input

Hicham G. Elmongui wrote:[color=blue]
> I need this for a side project. Is there a way to do something like this:
>
> SELECT *
> FROM DelayedTable('t ablename', 5);[/color]

No, at my knowledge you'll obtain the first tuple only when
the function exit.


Regards
Gaetano Mendola

[Alvaro Herrera]

Re: delayed input

On Tue, Oct 19, 2004 at 01:44:34PM -0500, Hicham G. Elmongui wrote:[color=blue]
> I need this for a side project. Is there a way to do something like this:
>
> SELECT *
> FROM DelayedTable('t ablename', 5);[/color]

You can probably build a sleep() function in C, and then use that to
cause delaying in a PL/pgSQL set-returning function. Something like

#include <postgres.h>
#include <fmgr.h>

PG_FUNCTION_INF O_V1(sleep);

Datum
sleep(PG_FUNCTI ON_ARGS)
{
int32 delay = PG_GETARG_INT32 (0);
sleep(delay);
PG_RETURN_VOID( );
}

--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
La web junta la gente porque no importa que clase de mutante sexual seas,
tienes millones de posibles parejas. Pon "buscar gente que tengan sexo con
ciervos incendiándose", y el computador dirá "especifiqu e el tipo de ciervo"
(Jason Alexander)


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[Hicham G. Elmongui]

Re: delayed input

Well, it seems that i have to build the scan operator myself. Even the
FunctionScan will make all the function calls and stores the result in a
tuuplestore. So, all the delay will be occured only at the first function
invocation.
--h




"Alvaro Herrera" <alvherre@dcc.u chile.cl> wrote in message
news:2004101919 1943.GC5625@dcc .uchile.cl...[color=blue]
> On Tue, Oct 19, 2004 at 01:44:34PM -0500, Hicham G. Elmongui wrote:[color=green]
> > I need this for a side project. Is there a way to do something like[/color][/color]
this:[color=blue][color=green]
> >
> > SELECT *
> > FROM DelayedTable('t ablename', 5);[/color]
>
> You can probably build a sleep() function in C, and then use that to
> cause delaying in a PL/pgSQL set-returning function. Something like
>
> #include <postgres.h>
> #include <fmgr.h>
>
> PG_FUNCTION_INF O_V1(sleep);
>
> Datum
> sleep(PG_FUNCTI ON_ARGS)
> {
> int32 delay = PG_GETARG_INT32 (0);
> sleep(delay);
> PG_RETURN_VOID( );
> }
>
> --
> Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
> La web junta la gente porque no importa que clase de mutante sexual seas,
> tienes millones de posibles parejas. Pon "buscar gente que tengan sexo con
> ciervos incendiándose", y el computador dirá "especifiqu e el tipo de[/color]
ciervo"[color=blue]
> (Jason Alexander)
>
>
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> TIP 6: Have you searched our list archives?
>
> http://archives.postgresql.org
>[/color]