Re: scrollable cursor sup. for SPI - Mailing list pgsql-patches

From Bruce Momjian
Subject Re: scrollable cursor sup. for SPI
Date
Msg-id 200701200147.l0K1lRC20154@momjian.us
Whole thread Raw
In response to Re: scrollable cursor sup. for SPI  ("Pavel Stehule" <pavel.stehule@hotmail.com>)
Responses Re: scrollable cursor sup. for SPI  ("Pavel Stehule" <pavel.stehule@hotmail.com>)
List pgsql-patches
Where are we on this patch?

---------------------------------------------------------------------------

Pavel Stehule wrote:
>
> >"Pavel Stehule" <pavel.stehule@hotmail.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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