Horton

Re: Modify the DECLARE CURSOR command tag depending on the scrollable flag

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Eisentraut <peter_e@gmx.net>
Cc: Boszormenyi Zoltan <zb@cybertec.at>, Alvaro Herrera <alvherre@2ndquadrant.com>, Michael Meskes <meskes@postgresql.org>, Noah Misch <noah@leadboat.com>, Robert Haas <robertmhaas@gmail.com>, PG Hackers <pgsql-hackers@postgresql.org>, Heikki Linnakangas <hlinnakangas@vmware.com>, Bruce Momjian <bruce@momjian.us>, Hans-Jürgen Schönig <hs@cybertec.at>
Date: 2013-11-27T23:17:16Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix some "translator:" comments mangled by pgindent

  2. Make sure float4in/float8in accept all standard spellings of "infinity".

Peter Eisentraut <peter_e@gmx.net> writes:
> On 11/27/13, 3:47 PM, Tom Lane wrote:
>> Given these considerations, I think it'd be better to allow explicit
>> application control over whether read-ahead happens for a particular
>> query.  And I have no problem whatsoever with requiring that the cursor
>> be explicitly marked SCROLL or NO SCROLL before read-ahead will occur.

> Well, technically, unspecified means NO SCROLL according to the SQL
> standard.  A lot of applications in ECPG are ported from other systems,
> which might make that assumption.  It wouldn't be very nice to have to
> change all that.

Hm.  So you're suggesting that ECPG fix this problem by inserting an
explicit NO SCROLL clause into translated DECLARE CURSOR commands, if
there's not a SCROLL clause?

That would solve the problem of the ECPG library not being sure which
behavior applies, but it might break existing apps that were unknowingly
relying on a simple cursor being scrollable.  OTOH any such app would be
subject to breakage anyway as a result of planner changes, so it's hard to
complain against this, as long as it's happening in a major version
update.

I'm for it.

			regards, tom lane