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Re: scrollable cursor sup. for SPI

From: "Pavel Stehule" <pavel(dot)stehule(at)hotmail(dot)com>
To: bruce(at)momjian(dot)us
Cc: tgl(at)sss(dot)pgh(dot)pa(dot)us, neilc(at)samurai(dot)com, pgsql-patches(at)postgresql(dot)org, jonah(dot)harris(at)gmail(dot)com
Subject: Re: scrollable cursor sup. for SPI
Date: 2007-01-20 09:52:54
Message-ID: BAY114-F28F602CBB63DDCE3BD8E03F9A80@phx.gbl (view raw or flat)
Thread:
Lists: pgsql-patches
Hello,

I am working on new version. Old patch doesn't solve scrollability well.

Regards
Pavel Stehule
>
>
>Where are we on this patch?
>
>---------------------------------------------------------------------------
>
>Pavel Stehule wrote:
> >
> > >"Pavel Stehule" <pavel(dot)stehule(at)hotmail(dot)com> writes:
> > > > if I comprehended it well CURSOR_OPT_SCROLL is set only when SCROLL 
>is
> > >cheap
> > > > (not when is possible). It's true?
> > >
> > >Nope.  If you want a scrollable plan you need to make sure you tell the
> > >planner about it.  SPI_cursor_open is not in charge, it's merely 
>looking
> > >at what the planner did.
> > >
> > >As for that other stuff, when and if we support it, it would be time to
> > >add a SPI entry point that supports it.  I'm disinclined to add an API
> > >on speculation though --- by the time the feature actually exists, we
> > >might not like the API anymore anyway.
> > >
> >
> > I did step back and did some test. game with CURSOR_OPT_SCROLL has not 
>sense
> > in SPI_cursor_open. I didn't tests with table's joins where this problem 
>is
> > visible before.
> >
> > I propose add new function SPI_prepare_with_option(..) which allow set
> > option for planner. Isn't problem add to SPI_open_cursor assert for 
>holdable
> > cursors. This needs propably rewriting functions pg_plan_query and
> > pg_plan_queries.
> >
> > Or new function SPI_prepare_cursor(...) which can be similar
> > PerformCursorOpen. This doesn't change others functions.
> >
> > All comments are welcome
> > Pavel Stehule
> >
> > _________________________________________________________________
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>--
>   Bruce Momjian   bruce(at)momjian(dot)us
>   EnterpriseDB    http://www.enterprisedb.com
>
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