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

Peter Eisentraut <peter_e(at)gmx(dot)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