Re: Don't overwrite scan key in systable_beginscan()

On 09.08.24 06:55, Tom Lane wrote:
> Noah Misch <noah(at)leadboat(dot)com> writes:
>> On Thu, Aug 08, 2024 at 08:46:35AM +0200, Peter Eisentraut wrote:
>>> I propose to fix that by making a copy of the scan keys passed by the caller
>>> and make the modifications there.
>
>> No objection, but this would obsolete at least some of these comments (the
>> catcache.c ones if nothing else):
>
> That ties into something I forgot to ask: aren't there any copy steps
> or other overhead that we could remove, given this new API constraint?
> That would help address Robert's concern.

I added two more patches to the series here.

First (or 0004), some additional cleanup for code that had to workaround
systable_beginscan() overwriting the scan keys, along the lines
suggested by Noah.

Second (or 0005), an alternative to palloc is to make the converted scan
keys a normal local variable. Then it's just a question of whether a
smaller palloc is preferred over an over-allocated local variable. I
think I still prefer the palloc version, but it doesn't matter much
either way I think.