| From: | Andy Fan <zhihuifan1213(at)163(dot)com> |
|---|---|
| To: | Nikita Malakhov <hukutoc(at)gmail(dot)com> |
| Cc: | Andrei Lepikhov <lepihov(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, David Rowley <dgrowleyml(at)gmail(dot)com> |
| Subject: | Re: Considering fractional paths in Append node |
| Date: | 2024-10-17 23:36:37 |
| Message-ID: | 87msj2qp2y.fsf@163.com |
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| Lists: | pgsql-hackers |
Nikita Malakhov <hukutoc(at)gmail(dot)com> writes:
> Hi,
>
> Andy, your words make sense, but to me it seems that in add_paths_to_append_rel
> we have no other options than tuple_fraction from root, and rows (if any) in paths
> we take into account, please correct me if I am wrong.
One of the option might be applying your logic only if we can prove the
tuple_fraction from root is same as the tuple_fraction, similar with
what I did before. But it is proved that is too complex.
> Thank you!
>
> Also, on top of that I have an idea of pruning unnecessary partitions
> in generate_orderedappend_paths() when we have a valid LIMIT value.
> I'm currently checking if it is working correctly in multiple cases,
> so 'll send it after we deal with this issue.
--
Best Regards
Andy Fan
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