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Re: scrollable cursor support without MOVE statement

From: "Pavel Stehule" <pavel(dot)stehule(at)hotmail(dot)com>
To: simon(at)2ndquadrant(dot)com
Cc: pgsql-patches(at)postgresql(dot)org, magnus(at)hagander(dot)net, bruce(at)momjian(dot)us
Subject: Re: scrollable cursor support without MOVE statement
Date: 2007-04-18 04:37:55
Message-ID: BAY114-F15A6EC6A2AADC37EDF3E25F9500@phx.gbl (view raw or flat)
Thread:
Lists: pgsql-patches
>On Wed, 2007-03-28 at 17:42 +0200, Pavel Stehule wrote:
> > >
> > >This is the most recent email I have on this.  Was the scrollable patch
> > >applied?  If not, would you resubmit?
> > >
> >
> > I resubmit scrollable cursor patch
>
>I notice your patch has been accepted, though admit I hadn't noticed it
>previously.

I resubmited this patch because Bruce removed it from queue instead of GUC 
protection patch

>
>Can I ask a question relating to the patch?
>How is the scrollability determined?
>
>Scrollable cursors and sorts don't mix very well in terms of
>performance, as you may know. Previously, since NOSCROLL was the only
>option, this wasn't a problem. Now that we have scrollable cursors, it
>is an issue, since according to the doc change the scrollability default
>is neither scroll nor noscroll.

default is noscroll

>
>I'm concerned that many PL/pgSQL routines will now run slower because
>they may now be considered scrollable when they previously were not. How
>is the scrollability determined? Do we look at the kids of FETCH being
>used to determine whether we need scrolling? (which would be great) Or
>will we have to manually change all existing PL/pgSQL code so that it is
>definitely NOSCROLL? (which would be unacceptable). Or?
>

default is without changes on functionality.

Regards
Pavel Stehule

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