Re: [HACKERS] tuplesort_gettuple_common() and *should_free argument

On Wed, Jan 25, 2017 at 3:11 PM, Peter Geoghegan  wrote:
> On Wed, Jan 25, 2017 at 3:11 PM, Tom Lane  wrote:
>> Please.  You might want to hit the existing ones with a separate patch,
>> but it doesn't much matter; I'd be just as happy with a patch that did
>> both things.
>
> Got it.

Attached is a patch that does both things at once. The internal
function tuplesort_gettuple_common() still mentions repeated fetches,
since that context matters to its internal callers. The various
external-facing functions have a simpler, stricter contract, as
discussed.

I didn't end up adding a line like "copy=FALSE is recommended only
when the next tuplesort manipulation will be another
tuplesort_gettupleslot fetch into the same slot", which you suggested.
When the tuplesort state machine is in any state following
"performing" a sort, there are very few remaining sane manipulations.
Just things like skipping or seeking around for tuples, and actually
ending the tuplesort and releasing resources.

-- 
Peter Geoghegan

-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers