On Mon, May 25, 2020 at 2:34 AM David Rowley <dgrowle...@gmail.com> wrote:
> On Sun, 24 May 2020 at 04:14, Dmitry Dolgov <9erthali...@gmail.com> wrote: > > > > > On Fri, May 22, 2020 at 08:40:17AM +1200, David Rowley wrote: > > > I imagine we'll set some required UniqueKeys during > > > standard_qp_callback() > > > > In standard_qp_callback, because pathkeys are computed at this point I > > guess? > > Yes. In particular, we set the pathkeys for DISTINCT clauses there. > > Actually I have some issues to understand from here, then try to read index skip scan patch to fully understand what is the requirement, but that doesn't get it so far[1]. So what is the "UniqueKeys" in "UniqueKeys during standard_qp_callback()" and what is the "pathkeys" in "pathkeys are computed at this point” means? I tried to think it as root->distinct_pathkeys, however I didn't fully understand where root->distinct_pathkeys is used for as well. [1] https://www.postgresql.org/message-id/CAKU4AWq%3DwWkAo-CDOQ5Ea6UwYvZCgb501w6iqU0rtnTT-zg6bQ%40mail.gmail.com -- Best Regards Andy Fan
