On Sun, 27 Jul 2025 at 19:53, Tender Wang <tndrwang@gmail.com> wrote:
> While debugging the pull-up sublink codes, I noticed the convert_VALUES_to_ANY().
> The function is to convert "where colX in VALUES(xxx)" into SAOP. It firstly scans the values_list to
> make sure no volatile function is in this list, then it scans this values_list again to check that it
> only includes Const items.
>
> We can merge the two scans into one. This can reduce the time complexity from 2O(n) to O(n).
I imagine that >95% of the time, probably more, the VALUES list is
going to contain only Consts, and if anything is done here, then it
likely should be to skip the convert_testexpr() /
eval_const_expressions() rigmarole when the input is already Const.
The proposal to move the contain_volatile_functions() doesn't seem
like a good idea to me as technically putting it where you propose
makes it mostly redundant (eval_const_expressions() will never
evaluate a volatile function and return a Const). I suspect it's there
because it's a slightly cheaper pre-check, and if you move it to
inside the loop then you may end up doing a bunch of work in
eval_const_expressions(), such as function inlining, which will just
be thrown away if you discover that the next item in the VALUES list
has a volatile.
Might be worth checking the planning overheads of large VALUES list
and seeing if it's worth putting the call to convert_testexpr() and
eval_const_expressions() inside an if (!IsA(value, Const)).
David
