On 1 November 2018 at 12:11, Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote:
> I still have trouble imagining what exactly would the function do to
> determine if the optimization can be applied to substr() and similar
> collation-dependent cases.
I guess the function would have to check for a Const offset of 0, and
a collection, perhaps of "C" for the 1st arg. In any case, I wouldn't
want this idea to be hung up on the fact we can't determine how to
make substr() work correctly with it.
I'm most interested in date_trunc() and friends. A first cut
implementation would not have to implement functions for everything
that's possible to implement.
--
David Rowley http://www.2ndQuadrant.com/
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