On Mon, Nov 2, 2026 at 01:42:44PM -0800, Masahiko Sawada wrote: > I've pushed a fix (8628df8891a) for how parallel vacuum computes the > cost-based vacuum delay. As I mentioned in the commit message, while > the fix corrects the delay computation, it could make VACUUM with the > PARALLEL option and cost-based delay enabled slower after upgrading to > v19. I think it's worth mentioning this in the release notes so that > users can re-tune the cost-based delay parameters. I've attached the > patch to add the item to the "Migration to Version 19" section. Please > review it.
I have slightly reworded the patch and applied it, attached, thanks. -- Bruce Momjian <[email protected]> https://momjian.us EDB https://enterprisedb.com Do not let urgent matters crowd out time for investment in the future.
diff --git a/doc/src/sgml/release-19.sgml b/doc/src/sgml/release-19.sgml index a818984c946..0523775183b 100644 --- a/doc/src/sgml/release-19.sgml +++ b/doc/src/sgml/release-19.sgml @@ -303,6 +303,23 @@ large analytical queries to manually enable <acronym>JIT</acronym>. </para> </listitem> +<!-- +Author: Masahiko Sawada <[email protected]> +2026-11-02 [8628df889] Make parallel vacuum processes share the cost limit. +--> + +<listitem> +<para> +Change <link linkend="parallel-vacuum">parallel vacuum</link> leaders and workers to share the cost-based vacuum delay limit (Bharath Rupireddy) +<ulink url="&commit_baseurl;8628df889">§</ulink> +</para> + +<para> +Previously each worker process slept based only on the cost it incurred itself, so a parallel vacuum could consume several times the budget set by <link linkend="guc-vacuum-cost-limit"><varname>vacuum_cost_limit</varname></link>. +With this change, <link linkend="sql-vacuum"><command>VACUUM</command></link> with parallel workers and cost-based delay enabled might run slower than in previous releases. +</para> +</listitem> + <!-- Author: Amit Kapila <[email protected]> 2025-11-18 [3edaf29fa] Rename two columns in pg_stat_subscription_stats.
