[PATCH] Doc fix for autovacuum_max_parallel_workers

Hello team,

The autovacuum_max_parallel_workers is missing the following line that the other relevant autovacuum parameters mention:

yes. Was worth a double check and the only ones not SIGHUP are:

autovacuum_worker_slots
autovacuum_freeze_max_age
autovacuum_multixact_freeze_max_age

"This parameter can only be set in the postgresql.conf file or on the server command"

Makes sense to me. The wording ending with "...command line" LGTM.

--
Sami Imseih
Amazon Web Services (AWS)

On Thu, Oct 15, 2026 at 2:03 PM Sami Imseih <samimseih.pg@gmail.com> wrote:

"This parameter can only be set in the postgresql.conf file or on the

server command"

Makes sense to me. The wording ending with "...command line" LGTM.

Thank you for the review. Is it worth to extend the wordings to *"... ;but
the setting can be *
*overridden for individual tables by changing table storage parameters"* as
the setting
can be changed at table level using autovacuum_parallel_workers [1]https://www.postgresql.org/docs/19/sql-createtable.html#RELOPTION-AUTOVACUUM-PARALLEL-WORKERS.

[1]: https://www.postgresql.org/docs/19/sql-createtable.html#RELOPTION-AUTOVACUUM-PARALLEL-WORKERS
https://www.postgresql.org/docs/19/sql-createtable.html#RELOPTION-AUTOVACUUM-PARALLEL-WORKERS

Thanks,
Baji Shaik

Thank you for the review. Is it worth to extend the wordings to "... ;but the setting can be
overridden for individual tables by changing table storage parameters" as the setting
can be changed at table level using autovacuum_parallel_workers [1].

I agree. It should do something similar to [1]https://www.postgresql.org/docs/19/runtime-config-vacuum.html#GUC-VACUUM-MAX-EAGER-FREEZE-FAILURE-RATE for consistency.

[1]: https://www.postgresql.org/docs/19/runtime-config-vacuum.html#GUC-VACUUM-MAX-EAGER-FREEZE-FAILURE-RATE

--
Sami

On Thu, Oct 15, 2026 at 3:21 PM Sami Imseih <samimseih.pg@gmail.com> wrote:

I agree. It should do something similar to [1] for consistency.

Thank you for the confirmation, Sami. v2 added. I followed the format of
other
autovacuum params which don't specifically point to the related storage
parameters.

Thanks,
Baji Shaik.

I agree. It should do something similar to [1] for consistency.

Thank you for the confirmation, Sami. v2 added. I followed the format of other
autovacuum params which don't specifically point to the related storage parameters.

I had this wording in mind:

"This parameter can only be set in the <filename>postgresql.conf</filename>
file or on the server command line; but the setting can be overridden for
individual tables by changing the
<link linkend="reloption-autovacuum-parallel-workers">corresponding table
storage parameter</link>."

That seems more helpful and matches [1]https://www.postgresql.org/docs/19/runtime-config-vacuum.html#GUC-VACUUM-MAX-EAGER-FREEZE-FAILURE-RATE, because it points to the specific
table storage parameter. In this case the reloption is named
autovacuum_parallel_workers while the GUC is autovacuum_max_parallel_workers,
so a link makes that clearer.

[1]: https://www.postgresql.org/docs/19/runtime-config-vacuum.html#GUC-VACUUM-MAX-EAGER-FREEZE-FAILURE-RATE

--
Sami

On Thu, Oct 15, 2026 at 4:21 PM Sami Imseih <samimseih.pg@gmail.com> wrote:

I had this wording in mind:

"This parameter can only be set in the <filename>postgresql.conf</filename>
file or on the server command line; but the setting can be overridden for
individual tables by changing the
<link linkend="reloption-autovacuum-parallel-workers">corresponding table
storage parameter</link>."

That seems more helpful and matches [1], because it points to the specific
table storage parameter. In this case the reloption is named
autovacuum_parallel_workers while the GUC is
autovacuum_max_parallel_workers,
so a link makes that clearer.

[1]
https://www.postgresql.org/docs/19/runtime-config-vacuum.html#GUC-VACUUM-MAX-EAGER-FREEZE-FAILURE-RATE

yeah, I had the same patch but thought to match with the other set of
params, however,
your point makes sense. v3 updated with the recommendation. Thank you very
much.

Thanks,
Baji Shaik.

On Fri, Oct 16, 2026 at 7:01 AM Baji Shaik <baji.pgdev@gmail.com> wrote:

v3 updated with the recommendation.

+ line; but the setting can be overridden for individual tables by

"overridden" should be "reduced" here? IIUC, this GUC remains an upper limit
even when the table storage parameter is set, so the table parameter can
lower the limit but cannot raise it. Both autovacuum_freeze_max_age and
autovacuum_multixact_freeze_max_age seem to use "reduced" for the same
reason.

Regards,

--
Fujii Masao

On Thu, Oct 15, 2026 at 6:34 PM Fujii Masao <masao.fujii@gmail.com> wrote:

On Fri, Oct 16, 2026 at 7:01 AM Baji Shaik <baji.pgdev@gmail.com> wrote:

+ line; but the setting can be overridden for individual tables by

"overridden" should be "reduced" here? IIUC, this GUC remains an upper
limit
even when the table storage parameter is set, so the table parameter can
lower the limit but cannot raise it. Both autovacuum_freeze_max_age and
autovacuum_multixact_freeze_max_age seem to use "reduced" for the same
reason.

That's a good point. Thank you for the review and correction. v4 attached.

Thanks,
Baji Shaik.

On Oct 16, 2026, at 08:22, Baji Shaik <baji.pgdev@gmail.com> wrote:

On Thu, Oct 15, 2026 at 6:34 PM Fujii Masao <masao.fujii@gmail.com> wrote:
On Fri, Oct 16, 2026 at 7:01 AM Baji Shaik <baji.pgdev@gmail.com> wrote:

+ line; but the setting can be overridden for individual tables by

"overridden" should be "reduced" here? IIUC, this GUC remains an upper limit
even when the table storage parameter is set, so the table parameter can
lower the limit but cannot raise it. Both autovacuum_freeze_max_age and
autovacuum_multixact_freeze_max_age seem to use "reduced" for the same
reason.

That's a good point. Thank you for the review and correction. v4 attached.

Thanks,
Baji Shaik.
<v4-0001-doc-say-where-autovacuum_max_parallel_workers-can.patch>

V4 looks good to me. “Reduced” accurately describes the implementation: parallel_vacuum_compute_workers() caps the table’s requested worker count at autovacuum_max_parallel_workers.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/

On Fri, Oct 16, 2026 at 9:22 AM Baji Shaik <baji.pgdev@gmail.com> wrote:

That's a good point. Thank you for the review and correction. v4 attached.

Thanks for updating the patch! I've pushed it.

Regards,

--
Fujii Masao