| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Richard Guo <guofenglinux(at)gmail(dot)com> |
| Cc: | Tomas Vondra <tomas(at)vondra(dot)me>, James Coleman <jtc331(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Consider low startup cost in add_partial_path |
| Date: | 2026-02-19 19:29:52 |
| Message-ID: | CA+Tgmob57CDgacucdcDhW+=jNQnB6J4wx9b+WujKboDJM18wBw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Feb 17, 2026 at 2:44 AM Richard Guo <guofenglinux(at)gmail(dot)com> wrote:
> Yeah, I agree that we should consider startup cost for partial paths,
> given that cost_gather (and cost_gather_merge) accounts for the
> subpath's startup_cost when calculating the cost of the Gather path.
>
> The changes LGTM. I noticed one comment that may need to be updated
> accordingly:
>
> * As in add_path, the partial_pathlist is kept sorted with the cheapest
> * total path in front. ...
>
> This is not true anymore. The partial_pathlist is now sorted by
> disabled_nodes and then by cheapest total cost.
Thanks. I have committed 0001 after adjusting that comment.
Here's the remaining patch once again. No comments on this one?
--
Robert Haas
EDB: http://www.enterprisedb.com
| Attachment | Content-Type | Size |
|---|---|---|
| v56-0001-Consider-startup-cost-as-a-figure-of-merit-for-p.patch | application/octet-stream | 17.1 KB |
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