Re: PATCH: generate fractional cheapest paths in generate_orderedappend_path

On Thu, Jun 3, 2021 at 11:12 AM Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>
wrote:

> Hi,
>
> On 6/3/21 7:17 PM, Arne Roland wrote:
> > Hi,
> >
> >
> > I haven't tested the parallel case, but I think we should sort out (3)
> > get_cheapest_fractional_path_for_pathkeys as mentioned above.
> >
>
> Not sure what you refer to by "above" - it's probably better to reply
> in-line to existing message, which makes it much cleared.
>
> >
> > I am lost about the comment regarding startup_new_fractional. Could you
> > elaborate what you mean by that?
> >
>
> Not sure what this refers to either - there's no startup_new_fractional
> in my message and 'git grep startup_new_fractional' returns nothing.
>
> >
> > Apart from that, I'd argue for a small test case. I attached a slimmed
> > down case of what we were trying to fix. It might be worth to integrate
> > that with an existing test, since more than a third of the time seems to
> > be consumed by the creation and attachment of partitions.
> >
>
> Maybe, if there's a suitable table to reuse, we can do that. But I don't
> think it matters it takes ~1/3 of the time to attach the partitions.
> What's more important is whether it measurably slows down the test
> suite, and I don't think that's an issue.
>
> In any case, this seems a bit premature - we need something to test the
> patch etc. We can worry about how expensive the test is much later.
>
> regards
>
> --
> Tomas Vondra
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>
>
> Hi,
In REL_11_STABLE branch, a search revealed the following:

src/backend/optimizer/path/pathkeys.c: *
get_cheapest_fractional_path_for_pathkeys
src/backend/optimizer/path/pathkeys.c:get_cheapest_fractional_path_for_pathkeys(List
*paths,
src/backend/optimizer/plan/planagg.c:
get_cheapest_fractional_path_for_pathkeys(final_rel->pathlist,
src/include/optimizer/paths.h:extern Path
*get_cheapest_fractional_path_for_pathkeys(List *paths,

It seems this function has been refactored out in subsequent releases.

FYI