Re: Improve UNION's output rowcount estimate - Mailing list pgsql-hackers

From Richard Guo
Subject Re: Improve UNION's output rowcount estimate
Date
Msg-id CAMbWs4_DE1Fh9MzJ3xE6PEkW9tcA2h_Ydu+-BJoX1ZskwOZT1w@mail.gmail.com
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In response to Re: Improve UNION's output rowcount estimate  (Chengpeng Yan <chengpeng_yan@outlook.com>)
List pgsql-hackers
On Thu, Jun 25, 2026 at 12:12 PM Chengpeng Yan
<chengpeng_yan@outlook.com> wrote:
> The added regression test looks reasonable to me, since it checks the
> plan change that motivated the patch. One small question: would it be
> worth adding a direct row-estimate check, perhaps with a helper like
> planner_est.sql’s explain_mask_costs() so that rows= stays visible while
> cost/width are masked? The existing plan-shape test may already be
> sufficient, though.

I think the plan-shape test is sufficient here.  I've committed this
patch to master.  Thanks for all the reviews.

- Richard



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