Horton
Menu

Thread

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. vacuumdb: Make vacuumdb --analyze-only process partitioned tables.

  2. Integrate FullTransactionIds deeper into two-phase code

  1. analyze-in-stages post upgrade questions

    Zechman, Derek S <derek.s.zechman@snapon.com> — 2025-06-27T13:35:27Z

    We recently performed an upgrade from pg14 (14.18) to pg16 (16.9) and performed the analyze-in-stages post upgrade.  It has been noticed that some plans changed to use hash joins instead of nested loops.  Further investigation found it was because the parent table of partitioned tables did not have stats.  After running an ANALYZE on the parent tables we got similar plan an execution times as before.

I have two questions
1 - Why does analyze-in-stages not analyze the parent tables?
2 - What happens if we do not run analyze-in-stages post upgrade and just run an analyze?

Thanks,
Sean

  2. Re: analyze-in-stages post upgrade questions

    Ron Johnson <ronljohnsonjr@gmail.com> — 2025-06-27T13:41:39Z

    On Fri, Jun 27, 2025 at 9:35 AM Zechman, Derek S <Derek.S.Zechman@snapon.com>
wrote:

>
>
> We recently performed an upgrade from pg14 (14.18) to pg16 (16.9) and
> performed the analyze-in-stages post upgrade.  It has been noticed that
> some plans changed to use hash joins instead of nested loops.  Further
> investigation found it was because the parent table of partitioned tables
> did not have stats.  After running an ANALYZE on the parent tables we got
> similar plan an execution times as before.
>
>
>
> I have two questions
>
> 1 - Why does analyze-in-stages not analyze the parent tables?
>
> 2 – What happens if we do not run analyze-in-stages post upgrade and just
> run an analyze?
>

It takes more time, and you don't have *any* statistics on a given table
until the ANALYZE on that table completes.

How long did "vacuumdb --analyze-only --jobs=$mumble your_db" take?

-- 
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!

  3. Re: analyze-in-stages post upgrade questions

    Adrian Klaver <adrian.klaver@aklaver.com> — 2025-06-27T15:31:08Z

    On 6/27/25 06:35, Zechman, Derek S wrote:
> We recently performed an upgrade from pg14 (14.18) to pg16 (16.9) and 
> performed the analyze-in-stages post upgrade.  It has been noticed that 
> some plans changed to use hash joins instead of nested loops.  Further 
> investigation found it was because the parent table of partitioned 
> tables did not have stats.  After running an ANALYZE on the parent 
> tables we got similar plan an execution times as before.
> 
> I have two questions
> 
> 1 - Why does analyze-in-stages not analyze the parent tables?
> 
> 2 – What happens if we do not run analyze-in-stages post upgrade and 
> just run an analyze?

It is spelled out in the docs:

https://www.postgresql.org/docs/current/pgupgrade.html

Emphasis added

"Using vacuumdb --all --analyze-only can efficiently generate such 
statistics, and the use of --jobs can speed it up. Option 
--analyze-in-stages can be used to generate **minimal statistics** 
quickly. If vacuum_cost_delay is set to a non-zero value, this can be 
overridden to speed up statistics generation using PGOPTIONS, e.g., 
PGOPTIONS='-c vacuum_cost_delay=0' vacuumdb ...."

and from here:

https://www.postgresql.org/docs/current/app-vacuumdb.html

"--analyze-in-stages

     Only calculate statistics for use by the optimizer (no vacuum), 
like --analyze-only. Run three stages of analyze; the first stage uses 
the lowest possible statistics target (see default_statistics_target) to 
produce usable statistics faster, and subsequent stages build the full 
statistics.

     This option is only useful to analyze a database that currently has 
no statistics or has wholly incorrect ones, such as if it is newly 
populated from a restored dump or by pg_upgrade. Be aware that running 
with this option in a database with existing statistics may cause the 
query optimizer choices to become transiently worse due to the low 
statistics targets of the early stages.
"

> 
> Thanks,
> 
> Sean
> 

-- 
Adrian Klaver
adrian.klaver@aklaver.com

  4. Re: analyze-in-stages post upgrade questions

    Laurenz Albe <laurenz.albe@cybertec.at> — 2025-06-27T21:39:17Z

    On Fri, 2025-06-27 at 08:31 -0700, Adrian Klaver wrote:
> On 6/27/25 06:35, Zechman, Derek S wrote:
> > We recently performed an upgrade from pg14 (14.18) to pg16 (16.9) and 
> > performed the analyze-in-stages post upgrade.  It has been noticed that 
> > some plans changed to use hash joins instead of nested loops.  Further 
> > investigation found it was because the parent table of partitioned 
> > tables did not have stats.  After running an ANALYZE on the parent 
> > tables we got similar plan an execution times as before.
> > 
> > I have two questions
> > 
> > 1 - Why does analyze-in-stages not analyze the parent tables?
> > 
> > 2 – What happens if we do not run analyze-in-stages post upgrade and 
> > just run an analyze?
> 
> It is spelled out in the docs:
> 
> https://www.postgresql.org/docs/current/pgupgrade.html
> 
> Emphasis added
> 
> "Using vacuumdb --all --analyze-only can efficiently generate such 
> statistics, and the use of --jobs can speed it up. Option 
> --analyze-in-stages can be used to generate **minimal statistics** 
> quickly. If vacuum_cost_delay is set to a non-zero value, this can be 
> overridden to speed up statistics generation using PGOPTIONS, e.g., 
> PGOPTIONS='-c vacuum_cost_delay=0' vacuumdb ...."
> 
> and from here:
> 
> https://www.postgresql.org/docs/current/app-vacuumdb.html
> 
> "--analyze-in-stages
> 
>      Only calculate statistics for use by the optimizer (no vacuum), 
> like --analyze-only. Run three stages of analyze; the first stage uses 
> the lowest possible statistics target (see default_statistics_target) to 
> produce usable statistics faster, and subsequent stages build the full 
> statistics.
> 
>      This option is only useful to analyze a database that currently has 
> no statistics or has wholly incorrect ones, such as if it is newly 
> populated from a restored dump or by pg_upgrade. Be aware that running 
> with this option in a database with existing statistics may cause the 
> query optimizer choices to become transiently worse due to the low 
> statistics targets of the early stages.

Well, that wouldn't explain why it doesn't work on partitioned tables.
I am under the impression that it should.

Derek, can cou share the pg_stats entries for the partitioned table?

Yours,
Laurenz Albe

  5. RE: analyze-in-stages post upgrade questions

    Zechman, Derek S <derek.s.zechman@snapon.com> — 2025-06-28T01:11:19Z

    

We recently performed an upgrade from pg14 (14.18) to pg16 (16.9) and performed the analyze-in-stages post upgrade.  It has been noticed that some plans changed to use hash joins instead of nested loops.  Further investigation found it was because the parent table of partitioned tables did not have stats.  After running an ANALYZE on the parent tables we got similar plan an execution times as before.

I have two questions
1 - Why does analyze-in-stages not analyze the parent tables?
2 – What happens if we do not run analyze-in-stages post upgrade and just run an analyze?

“It takes more time, and you don't have any statistics on a given table until the ANALYZE on that table completes.

How long did "vacuumdb --analyze-only --jobs=$mumble your_db" take?”

Thanks – that makes sense.  I understand what analyze in stages does just wish it would include parent tables.

"vacuumdb --all --analyze-only --jobs=7" took about 75 minutes where the analyze-in-stages after upgrade took 115 minutes.  Neither of these activities analyzed the parent tables.
Reading more and it seems vacuumdb doesn’t analyze parent tables and a manual analyze on those is needed if we want better planner statistics.

  6. RE: analyze-in-stages post upgrade questions

    Zechman, Derek S <derek.s.zechman@snapon.com> — 2025-06-28T01:23:59Z

    > > We recently performed an upgrade from pg14 (14.18) to pg16 (16.9) and

> > performed the analyze-in-stages post upgrade.  It has been noticed that

> > some plans changed to use hash joins instead of nested loops.  Further

> > investigation found it was because the parent table of partitioned

> > tables did not have stats.  After running an ANALYZE on the parent

> > tables we got similar plan an execution times as before.

> >

> > I have two questions

> >

> > 1 - Why does analyze-in-stages not analyze the parent tables?

> >

> > 2 – What happens if we do not run analyze-in-stages post upgrade and

> > just run an analyze?

>

> It is spelled out in the docs:

>

> https://urldefense.com/v3/__https://www.postgresql.org/docs/current/pgupgrade.html__;!!Lf_9VycLqA!jU5QgA1re0Txg_h2dD1N3XvK_l8hYdyMvpcxrLL5GDyQ5qN4aGQcxmDE8qmaV_p5telTzYmOL6S3fR8eRc0s_8UvnFFR6Ws$<https://urldefense.com/v3/__https:/www.postgresql.org/docs/current/pgupgrade.html__;!!Lf_9VycLqA!jU5QgA1re0Txg_h2dD1N3XvK_l8hYdyMvpcxrLL5GDyQ5qN4aGQcxmDE8qmaV_p5telTzYmOL6S3fR8eRc0s_8UvnFFR6Ws$>

>

> Emphasis added

>

> "Using vacuumdb --all --analyze-only can efficiently generate such

> statistics, and the use of --jobs can speed it up. Option

> --analyze-in-stages can be used to generate **minimal statistics**

> quickly. If vacuum_cost_delay is set to a non-zero value, this can be

> overridden to speed up statistics generation using PGOPTIONS, e.g.,

> PGOPTIONS='-c vacuum_cost_delay=0' vacuumdb ...."

>

> and from here:

>

> https://urldefense.com/v3/__https://www.postgresql.org/docs/current/app-vacuumdb.html__;!!Lf_9VycLqA!jU5QgA1re0Txg_h2dD1N3XvK_l8hYdyMvpcxrLL5GDyQ5qN4aGQcxmDE8qmaV_p5telTzYmOL6S3fR8eRc0s_8UvvC7gfd0$<https://urldefense.com/v3/__https:/www.postgresql.org/docs/current/app-vacuumdb.html__;!!Lf_9VycLqA!jU5QgA1re0Txg_h2dD1N3XvK_l8hYdyMvpcxrLL5GDyQ5qN4aGQcxmDE8qmaV_p5telTzYmOL6S3fR8eRc0s_8UvvC7gfd0$>

>

> "--analyze-in-stages

>

>      Only calculate statistics for use by the optimizer (no vacuum),

> like --analyze-only. Run three stages of analyze; the first stage uses

> the lowest possible statistics target (see default_statistics_target) to

> produce usable statistics faster, and subsequent stages build the full

> statistics.

>

>      This option is only useful to analyze a database that currently has

> no statistics or has wholly incorrect ones, such as if it is newly

> populated from a restored dump or by pg_upgrade. Be aware that running

> with this option in a database with existing statistics may cause the

> query optimizer choices to become transiently worse due to the low

> statistics targets of the early stages.



Well, that wouldn't explain why it doesn't work on partitioned tables.

I am under the impression that it should.



Derek, can cou share the pg_stats entries for the partitioned table?



Yours,

Laurenz Albe





There are no entries in pg_stats for the parent table until after I manually run an analyze on it – Example below



=> select relname, reltuples, relkind from pg_class where relname ~ '^chapter_[0-9]+$' or relname='chapter' order by 1;

   relname   | reltuples | relkind

-------------+-----------+---------

 chapter     |        -1 | p

 chapter_1   |         4 | r

 chapter_10  |         4 | r

 chapter_100 |        30 | r

 chapter_101 |        15 | r

 chapter_102 |        15 | r

…

=> select count(*) from pg_stats where tablename='chapter';

 count

-------

     0

(1 row)



=> analyze chapter;

ANALYZE

=> select relname, reltuples, relkind from pg_class where relkind ='p' and relname='chapter';

 relname | reltuples | relkind

---------+-----------+---------

 chapter |      7589 | p

(1 row)



=> select count(*) from pg_stats where tablename='chapter';

 count

-------

    49

(1 row)



toy_epc_stg_1_db=>

  7. Re: analyze-in-stages post upgrade questions

    Laurenz Albe <laurenz.albe@cybertec.at> — 2025-06-28T05:25:30Z

    On Sat, 2025-06-28 at 01:23 +0000, Zechman, Derek S wrote:
> > Well, that wouldn't explain why it doesn't work on partitioned tables.
> > I am under the impression that it should.
> >
> > Derek, can cou share the pg_stats entries for the partitioned table?
> 
> There are no entries in pg_stats for the parent table until after I manually run an analyze on it – Example below

You are right.  I looked at the code, and "vacuumdb" does not process
partitiond tables, even if --analyze-only is specified.  I find that
surprising, aince the SQL command ANALYZE (without a table name) will
also collect statistics for partitioned tables.

I think that it would be a good idea to change that behavior.
In particular, it makes a lot of sense to collect statistics for
partitioned tables after a "pg_upgrade".

Attached is a patch to make "vacuumdb --analyze-only" consider
partitioned tables as well.

Yours,
Laurenz Albe

  8. Re: analyze-in-stages post upgrade questions

    Mircea Cadariu <cadariu.mircea@gmail.com> — 2025-07-07T12:43:11Z

    The following review has been posted through the commitfest application:
make installcheck-world:  tested, passed
Implements feature:       tested, passed
Spec compliant:           tested, passed
Documentation:            tested, passed

Hi Laurenz,

Nice focused patch. 

Applied successfully on commit 62a17a92 from master. 

Documentation is updated and there is an explanatory comment for the code, as well as a descriptive commit message. 

To check the patch, I added the following test at the end of src/bin/scripts/t/100_vacuumdb.pl in both master (as experiment) and your patch. In master it does not pass, but with your patch applied it does. 

You can consider adding it to your patch, or I could also do that. 

$node->safe_psql('postgres',
    "CREATE TABLE parent_table (a INT) PARTITION BY LIST (a);\n"
      . "CREATE TABLE child_table PARTITION OF parent_table FOR VALUES IN (1);\n"
      . "INSERT INTO parent_table VALUES (1);\n");
$node->issues_sql_like(
    [
        'vacuumdb', '--analyze-only', 'postgres'
    ],
    qr/statement:\s+ANALYZE\s+public\.parent_table/s,
    '--analyze_only updates statistics for partitioned tables');

Kind regards,
Mircea Cadariu

The new status of this patch is: Waiting on Author

  9. RE: analyze-in-stages post upgrade questions

    Zechman, Derek S <derek.s.zechman@snapon.com> — 2025-07-09T11:30:22Z

    > > Well, that wouldn't explain why it doesn't work on partitioned tables.

> > I am under the impression that it should.

> >

> > Derek, can cou share the pg_stats entries for the partitioned table?

>

> There are no entries in pg_stats for the parent table until after I manually run an analyze on it – Example below



You are right.  I looked at the code, and "vacuumdb" does not process

partitiond tables, even if --analyze-only is specified.  I find that

surprising, aince the SQL command ANALYZE (without a table name) will

also collect statistics for partitioned tables.



I think that it would be a good idea to change that behavior.

In particular, it makes a lot of sense to collect statistics for

partitioned tables after a "pg_upgrade".



Attached is a patch to make "vacuumdb --analyze-only" consider

partitioned tables as well.



Yours,

Laurenz Albe



Is there a plan to include this patch in future releases/patches of postgres?



Thanks,

(Derek) Sean

  10. Re: analyze-in-stages post upgrade questions

    Laurenz Albe <laurenz.albe@cybertec.at> — 2025-07-09T15:26:02Z

    On Wed, 2025-07-09 at 11:30 +0000, Zechman, Derek S wrote:
> > > There are no entries in pg_stats for the parent table until after I manually run an analyze on it – Example below
> >
> > You are right.  I looked at the code, and "vacuumdb" does not process
> > partitiond tables, even if --analyze-only is specified.  I find that
> > surprising, aince the SQL command ANALYZE (without a table name) will
> > also collect statistics for partitioned tables.
> >
> > I think that it would be a good idea to change that behavior.
> > In particular, it makes a lot of sense to collect statistics for
> > partitioned tables after a "pg_upgrade".
> >
> > Attached is a patch to make "vacuumdb --analyze-only" consider
> > partitioned tables as well.
> 
> Is there a plan to include this patch in future releases/patches of postgres? 

I have added the patch to the current commitfest:
https://commitfest.postgresql.org/patch/5871/

So far, it has not got any peer review.  So yes, I'd like to include
the patch, but I cannot make it happen by myself.
Essentially, patches get applied if
a) they get peer review and
b) a committer applies them

If you want this to happen, the best thing you could do would be
to review the patch and see if it works for you, if it does what you
need and so on:
https://wiki.postgresql.org/wiki/Reviewing_a_Patch

Yours,
Laurenz Albe

  11. Re: analyze-in-stages post upgrade questions

    Mircea Cadariu <cadariu.mircea@gmail.com> — 2025-07-09T16:37:20Z

    Hi Laurenz,

On 09/07/2025 16:26, Laurenz Albe wrote:
> I have added the patch to the current commitfest:
> https://commitfest.postgresql.org/patch/5871/

Just to let you know that I have added a review through the commitfest app.

You can see it here: 
https://www.postgresql.org/message-id/flat/175189219162.2200286.3306593311375985296.pgcf@coridan.postgresql.org

Kind regards,

Mircea Cadariu

  12. Re: analyze-in-stages post upgrade questions

    Laurenz Albe <laurenz.albe@cybertec.at> — 2025-07-09T17:22:35Z

    On Wed, 2025-07-09 at 17:37 +0100, Mircea Cadariu wrote:
> Just to let you know that I have added a review through the commitfest app. 

Thanks!

The patch is still in state "needs review".
If there is something that I should change, you should set it to
"waiting on author".  If you think that the patch is ready to go
as it is, please set it to "ready for committer".

Yours,
Laurenz Albe

  13. Re: analyze-in-stages post upgrade questions

    Mircea Cadariu <cadariu.mircea@gmail.com> — 2025-07-10T16:20:02Z

    Hi Laurenz,


Got it. I have only one suggestion for the patch. Consider adding a 
corresponding test in src/bin/scripts/t/100_vacuumdb.pl.

Proposal (I used this to check the patch):

$node->safe_psql('postgres',
     "CREATE TABLE parent_table (a INT) PARTITION BY LIST (a);\n"
       . "CREATE TABLE child_table PARTITION OF parent_table FOR VALUES 
IN (1);\n"
       . "INSERT INTO parent_table VALUES (1);\n");
$node->issues_sql_like(
     [
         'vacuumdb', '--analyze-only', 'postgres'
     ],
     qr/statement:\s+ANALYZE\s+public\.parent_table/s,
     '--analyze_only updates statistics for partitioned tables');


Kind regards,

Mircea Cadariu

  14. Re: analyze-in-stages post upgrade questions

    Laurenz Albe <laurenz.albe@cybertec.at> — 2025-07-11T09:51:30Z

    [moving to pgsql-hackers]
On Thu, 2025-07-10 at 17:20 +0100, Mircea Cadariu wrote:
>       I have only one suggestion for the patch. Consider adding a 
> corresponding test in src/bin/scripts/t/100_vacuumdb.pl.
> 
> Proposal (I used this to check the patch):
> 
> $node->safe_psql('postgres',
>      "CREATE TABLE parent_table (a INT) PARTITION BY LIST (a);\n"
>        . "CREATE TABLE child_table PARTITION OF parent_table FOR VALUES 
> IN (1);\n"
>        . "INSERT INTO parent_table VALUES (1);\n");
> $node->issues_sql_like(
>      [
>          'vacuumdb', '--analyze-only', 'postgres'
>      ],
>      qr/statement:\s+ANALYZE\s+public\.parent_table/s,
>      '--analyze_only updates statistics for partitioned tables');

Good idea; done in the attached version 2 of the patch.

Yours,
Laurenz Albe

  15. Re: analyze-in-stages post upgrade questions

    Mircea Cadariu <cadariu.mircea@gmail.com> — 2025-07-11T10:42:44Z

    On 11/07/2025 10:51, Laurenz Albe wrote:

> Good idea; done in the attached version 2 of the patch.

Thanks! Looks good. I have set the status of the Commitfest entry to 
"Ready for Committer".


Kind regards,

Mircea Cadariu

  16. Re: analyze-in-stages post upgrade questions

    Fujii Masao <masao.fujii@gmail.com> — 2025-07-30T02:49:56Z

    On Fri, Jul 11, 2025 at 7:42 PM Mircea Cadariu <cadariu.mircea@gmail.com> wrote:
>
> On 11/07/2025 10:51, Laurenz Albe wrote:
>
> > Good idea; done in the attached version 2 of the patch.
>
> Thanks! Looks good. I have set the status of the Commitfest entry to
> "Ready for Committer".

I've started reviewing the patch since it's marked as ready for committer.

Overall, I like the change. But I have one question: should this be treated as
a bug fix that we back-patch to supported branches, or is it more of
an improvement that should only go into master?


         Only calculate statistics for use by the optimizer (no vacuum).
+        If that option is specified, <command>vacuumdb</command> will also
+        process partitioned tables.  Without that option, only the partitions
+        will be considered, unless a partitioned table is explicitly specified
+        with the <option>--table</option> option.

This wording seems a bit out of place in the --analyze-only section,
since it also describes the default behavior of vacuumdb without that option.
Wouldn't it make more sense to move that explanation in the --table section?

For example, we could add something like:

------------------
If no tables are specified with the --table option, vacuumdb will
clean all regular tables and materialized views in the connected
database. If --analyze-only or --analyze-in-stages is also specified,
it will analyze all regular tables, partitioned tables, and
materialized views (but not foreign tables).
------------------


+ /*
+ * VACUUMing partitioned tables would be unreasonably expensive, since
+ * that entails processing the partitions twice (once as part of the
+ * partitioned table, once as tables in their own right) for no
+ * benefit. But if we only ANALYZE, collecting statistics for
+ * partitioned tables is worth the effort.
+ */

This is probably true. But isn't the main reason more about aligning with
the behavior of the underlying VACUUM and ANALYZE commands? As the vacuumdb
docs says, "There is no effective difference between vacuuming and analyzing
databases via this utility and via other methods for accessing the server.",
so its default target objects should match: VACUUM skips partitioned tables
by default, while ANALYZE includes them. If that's the case, maybe the comment
should reflect that instead.


+ qr/statement:\s+ANALYZE\s+public\.parent_table/s,
+ '--analyze_only updates statistics for partitioned tables');

A plain space might be sufficient instead of \s+.
Also, I don't think the backslash before ".parent_table" is necessary.

Regards,

-- 
Fujii Masao

  17. Re: analyze-in-stages post upgrade questions

    Mircea Cadariu <cadariu.mircea@gmail.com> — 2025-08-06T04:01:18Z

    Hi,

On 30/07/2025 12:49, Fujii Masao wrote:
> I've started reviewing the patch since it's marked as ready for committer.
Thanks!
> Overall, I like the change. But I have one question: should this be treated as
> a bug fix that we back-patch to supported branches, or is it more of
> an improvement that should only go into master?
I reckon it might make sense to back-patch it to previous versions, as 
users might not upgrade always to the latest version.
>           Only calculate statistics for use by the optimizer (no vacuum).
> +        If that option is specified, <command>vacuumdb</command> will also
> +        process partitioned tables.  Without that option, only the partitions
> +        will be considered, unless a partitioned table is explicitly specified
> +        with the <option>--table</option> option.
>
> This wording seems a bit out of place in the --analyze-only section,
> since it also describes the default behavior of vacuumdb without that option.
> Wouldn't it make more sense to move that explanation in the --table section?
>
> For example, we could add something like:
>
> ------------------
> If no tables are specified with the --table option, vacuumdb will
> clean all regular tables and materialized views in the connected
> database. If --analyze-only or --analyze-in-stages is also specified,
> it will analyze all regular tables, partitioned tables, and
> materialized views (but not foreign tables).
> ------------------
Yes, agreed.
> + /*
> + * VACUUMing partitioned tables would be unreasonably expensive, since
> + * that entails processing the partitions twice (once as part of the
> + * partitioned table, once as tables in their own right) for no
> + * benefit. But if we only ANALYZE, collecting statistics for
> + * partitioned tables is worth the effort.
> + */
>
> This is probably true. But isn't the main reason more about aligning with
> the behavior of the underlying VACUUM and ANALYZE commands? As the vacuumdb
> docs says, "There is no effective difference between vacuuming and analyzing
> databases via this utility and via other methods for accessing the server.",
> so its default target objects should match: VACUUM skips partitioned tables
> by default, while ANALYZE includes them. If that's the case, maybe the comment
> should reflect that instead.
I see what you mean. From that perspective, I wonder if we even need a 
comment there at all.
> + qr/statement:\s+ANALYZE\s+public\.parent_table/s,
> + '--analyze_only updates statistics for partitioned tables');
>
> A plain space might be sufficient instead of \s+.
> Also, I don't think the backslash before ".parent_table" is necessary.

Good catch! Indeed let's simplify that to contain strictly only what's 
necessary.

Kind regards,

Mircea Cadariu

  18. Re: analyze-in-stages post upgrade questions

    Fujii Masao <masao.fujii@gmail.com> — 2025-08-06T14:25:53Z

    On Wed, Aug 6, 2025 at 1:01 PM Mircea Cadariu <cadariu.mircea@gmail.com> wrote:
> Overall, I like the change. But I have one question: should this be treated as
> a bug fix that we back-patch to supported branches, or is it more of
> an improvement that should only go into master?
>
> I reckon it might make sense to back-patch it to previous versions, as users might not upgrade always to the latest version.

I understand your point. But on second thought, since the patch changes
behavior, I'm leaning toward treating it as an improvement, so it should
only go to master...


> + /*
> + * VACUUMing partitioned tables would be unreasonably expensive, since
> + * that entails processing the partitions twice (once as part of the
> + * partitioned table, once as tables in their own right) for no
> + * benefit. But if we only ANALYZE, collecting statistics for
> + * partitioned tables is worth the effort.
> + */
>
> This is probably true. But isn't the main reason more about aligning with
> the behavior of the underlying VACUUM and ANALYZE commands? As the vacuumdb
> docs says, "There is no effective difference between vacuuming and analyzing
> databases via this utility and via other methods for accessing the server.",
> so its default target objects should match: VACUUM skips partitioned tables
> by default, while ANALYZE includes them. If that's the case, maybe the comment
> should reflect that instead.
>
> I see what you mean. From that perspective, I wonder if we even need a comment there at all.

Or, if we keep it, though, I'd like to update it to something like
the following:

--------------------
vacuumdb should generally follow the behavior of the underlying
VACUUM and ANALYZE commands. If analyze_only is true, process
regular tables, materialized views, and partitioned tables, just like
ANALYZE (with no specific target tables) does. Otherwise, process
only regular tables and materialized views, since VACUUM skips
partitioned tables when no target tables are specified.
--------------------

Regards,

-- 
Fujii Masao

  19. Re: analyze-in-stages post upgrade questions

    Nathan Bossart <nathandbossart@gmail.com> — 2025-08-06T18:14:12Z

    On Wed, Aug 06, 2025 at 11:25:53PM +0900, Fujii Masao wrote:
> On Wed, Aug 6, 2025 at 1:01 PM Mircea Cadariu <cadariu.mircea@gmail.com> wrote:
>> Overall, I like the change. But I have one question: should this be treated as
>> a bug fix that we back-patch to supported branches, or is it more of
>> an improvement that should only go into master?
>>
>> I reckon it might make sense to back-patch it to previous versions, as users might not upgrade always to the latest version.
> 
> I understand your point. But on second thought, since the patch changes
> behavior, I'm leaning toward treating it as an improvement, so it should
> only go to master...

I also am leaning towards treating this as v19 material.  It's a nontrivial
behavior change, and this option is useful for major version upgrades,
which is an area that we really don't want to surprise users too much.
Furthermore, auto-analyze doesn't process partitioned tables, either, so
this introduces a bit of divergence.  (I'd love to see that project picked
up again someday.  Perhaps I will take a gander...)

-- 
nathan

  20. Re: analyze-in-stages post upgrade questions

    Laurenz Albe <laurenz.albe@cybertec.at> — 2025-08-06T20:52:52Z

    On Wed, 2025-08-06 at 23:25 +0900, Fujii Masao wrote:
> On Wed, Aug 6, 2025 at 1:01 PM Mircea Cadariu <cadariu.mircea@gmail.com> wrote:
> > Overall, I like the change. But I have one question: should this be treated as
> > a bug fix that we back-patch to supported branches, or is it more of
> > an improvement that should only go into master?
> > 
> > I reckon it might make sense to back-patch it to previous versions, as users might not upgrade always to the latest version.
> 
> I understand your point. But on second thought, since the patch changes
> behavior, I'm leaning toward treating it as an improvement, so it should
> only go to master...

I agree that this behavior change should not be backpatched.
That is not a bugfix.

> > + /*
> > + * VACUUMing partitioned tables would be unreasonably expensive, since
> > + * that entails processing the partitions twice (once as part of the
> > + * partitioned table, once as tables in their own right) for no
> > + * benefit. But if we only ANALYZE, collecting statistics for
> > + * partitioned tables is worth the effort.
> > + */
> > 
> > This is probably true. But isn't the main reason more about aligning with
> > the behavior of the underlying VACUUM and ANALYZE commands? As the vacuumdb
> > docs says, "There is no effective difference between vacuuming and analyzing
> > databases via this utility and via other methods for accessing the server.",
> > so its default target objects should match: VACUUM skips partitioned tables
> > by default, while ANALYZE includes them. If that's the case, maybe the comment
> > should reflect that instead.
> > 
> > I see what you mean. From that perspective, I wonder if we even need a comment there at all.
> 
> Or, if we keep it, though, I'd like to update it to something like
> the following:
> 
> --------------------
> vacuumdb should generally follow the behavior of the underlying
> VACUUM and ANALYZE commands. If analyze_only is true, process
> regular tables, materialized views, and partitioned tables, just like
> ANALYZE (with no specific target tables) does. Otherwise, process
> only regular tables and materialized views, since VACUUM skips
> partitioned tables when no target tables are specified.
> --------------------

I am fine with that suggestion.

Alternatively, my original comment could be amended with

  Besides, ANALYZE (without an option) processes partitioned tables, and
  "vacuumdb -Z" should behave like ANALYZE.

Yours,
Laurenz Albe

  21. Re: analyze-in-stages post upgrade questions

    Fujii Masao <masao.fujii@gmail.com> — 2025-08-18T02:36:48Z

    On Thu, Aug 7, 2025 at 3:14 AM Nathan Bossart <nathandbossart@gmail.com> wrote:
> I also am leaning towards treating this as v19 material.  It's a nontrivial
> behavior change, and this option is useful for major version upgrades,
> which is an area that we really don't want to surprise users too much.

+1

> Furthermore, auto-analyze doesn't process partitioned tables, either, so
> this introduces a bit of divergence.  (I'd love to see that project picked
> up again someday.  Perhaps I will take a gander...)

Sounds good!

Regards,

-- 
Fujii Masao

  22. Re: analyze-in-stages post upgrade questions

    Fujii Masao <masao.fujii@gmail.com> — 2025-08-18T02:38:23Z

    On Thu, Aug 7, 2025 at 5:52 AM Laurenz Albe <laurenz.albe@cybertec.at> wrote:
> > I understand your point. But on second thought, since the patch changes
> > behavior, I'm leaning toward treating it as an improvement, so it should
> > only go to master...
>
> I agree that this behavior change should not be backpatched.
> That is not a bugfix.

+1

> > --------------------
> > vacuumdb should generally follow the behavior of the underlying
> > VACUUM and ANALYZE commands. If analyze_only is true, process
> > regular tables, materialized views, and partitioned tables, just like
> > ANALYZE (with no specific target tables) does. Otherwise, process
> > only regular tables and materialized views, since VACUUM skips
> > partitioned tables when no target tables are specified.
> > --------------------
>
> I am fine with that suggestion.

Thanks! So I've updated the patch based on my earlier comments.
Unless there are objections, I'll commit the attached version to master only.

Regards,

-- 
Fujii Masao

  23. Re: analyze-in-stages post upgrade questions

    Laurenz Albe <laurenz.albe@cybertec.at> — 2025-08-18T06:40:02Z

    On Mon, 2025-08-18 at 11:38 +0900, Fujii Masao wrote:
> Thanks! So I've updated the patch based on my earlier comments.
> Unless there are objections, I'll commit the attached version to master only.

I am fine with your patch.

One suggestion:

> --- a/doc/src/sgml/ref/vacuumdb.sgml
> +++ b/doc/src/sgml/ref/vacuumdb.sgml
> @@ -397,6 +397,15 @@ PostgreSQL documentation
>          Multiple tables can be vacuumed by writing multiple
>          <option>-t</option> switches.
>         </para>
> +       <para>
> +        If no tables are specified with the <option>--table</option> option,
> +        <application>vacuumdb</application> will clean all regular tables
> +        and materialized views in the connected database.
> +        If <option>--analyze-only</option> or
> +        <option>--analyze-in-stages</option> is also specified,
> +        it will analyze all regular tables, partitioned tables,
> +        and materialized views (but not foreign tables).
> +       </para>

I suggest replacing "clean" with "process", since VACUUM does so much more than
clean up dead tuples.

Concerning backpatching, I voted against, but I suggest that this be backpatched
to v18.  I don't feel very strongly about it though.

Yours,
Laurenz Albe

  24. Re: analyze-in-stages post upgrade questions

    Fujii Masao <masao.fujii@gmail.com> — 2025-08-19T14:40:05Z

    On Mon, Aug 18, 2025 at 3:40 PM Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> On Mon, 2025-08-18 at 11:38 +0900, Fujii Masao wrote:
> > Thanks! So I've updated the patch based on my earlier comments.
> > Unless there are objections, I'll commit the attached version to master only.
>
> I am fine with your patch.

Thanks for the review!


> One suggestion:
>
> > --- a/doc/src/sgml/ref/vacuumdb.sgml
> > +++ b/doc/src/sgml/ref/vacuumdb.sgml
> > @@ -397,6 +397,15 @@ PostgreSQL documentation
> >          Multiple tables can be vacuumed by writing multiple
> >          <option>-t</option> switches.
> >         </para>
> > +       <para>
> > +        If no tables are specified with the <option>--table</option> option,
> > +        <application>vacuumdb</application> will clean all regular tables
> > +        and materialized views in the connected database.
> > +        If <option>--analyze-only</option> or
> > +        <option>--analyze-in-stages</option> is also specified,
> > +        it will analyze all regular tables, partitioned tables,
> > +        and materialized views (but not foreign tables).
> > +       </para>
>
> I suggest replacing "clean" with "process", since VACUUM does so much more than
> clean up dead tuples.

I see your point. However, since the vacuumdb docs already use "clean"
in several places, I think it's better to keep using "clean" here
for consistency. Thought?


> Concerning backpatching, I voted against, but I suggest that this be backpatched
> to v18.  I don't feel very strongly about it though.

As for back-patching, I failed to find a strong reason to apply this change
to v18 over the many other patches that could not be committed before
the feature freeze... Of course if there's broad support for back-patching,
we can certainly revisit it. But for now I'm thinking to commit the patch
to master.

Regards,

-- 
Fujii Masao

  25. Re: analyze-in-stages post upgrade questions

    Laurenz Albe <laurenz.albe@cybertec.at> — 2025-08-19T15:16:12Z

    On Tue, 2025-08-19 at 23:40 +0900, Fujii Masao wrote:
> > > --- a/doc/src/sgml/ref/vacuumdb.sgml
> > > +++ b/doc/src/sgml/ref/vacuumdb.sgml
> > > @@ -397,6 +397,15 @@ PostgreSQL documentation
> > >           Multiple tables can be vacuumed by writing multiple
> > >           <option>-t</option> switches.
> > >          </para>
> > > +       <para>
> > > +        If no tables are specified with the <option>--table</option> option,
> > > +        <application>vacuumdb</application> will clean all regular tables
> > > +        and materialized views in the connected database.
> > > +        If <option>--analyze-only</option> or
> > > +        <option>--analyze-in-stages</option> is also specified,
> > > +        it will analyze all regular tables, partitioned tables,
> > > +        and materialized views (but not foreign tables).
> > > +       </para>
> > 
> > I suggest replacing "clean" with "process", since VACUUM does so much more than
> > clean up dead tuples.
> 
> I see your point. However, since the vacuumdb docs already use "clean"
> in several places, I think it's better to keep using "clean" here
> for consistency. Thought?

Works for me; I didn't consider that.

> > Concerning backpatching, I voted against, but I suggest that this be backpatched
> > to v18.  I don't feel very strongly about it though.
> 
> As for back-patching, I failed to find a strong reason to apply this change
> to v18 over the many other patches that could not be committed before
> the feature freeze... Of course if there's broad support for back-patching,
> we can certainly revisit it. But for now I'm thinking to commit the patch
> to master.

I don't have a strong reason either - my reasoning was that the change is small
and unlikely to introduce a bug, and that it would be nice to get more accurate
statistics on partitioned tables after "pg_upgrade" a year earlier.

But I won't object if the patch is only in v19.

Yours,
Laurenz Albe

  26. Re: analyze-in-stages post upgrade questions

    Fujii Masao <masao.fujii@gmail.com> — 2025-08-20T04:31:29Z

    On Wed, Aug 20, 2025 at 12:16 AM Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> On Tue, 2025-08-19 at 23:40 +0900, Fujii Masao wrote:
> > > > --- a/doc/src/sgml/ref/vacuumdb.sgml
> > > > +++ b/doc/src/sgml/ref/vacuumdb.sgml
> > > > @@ -397,6 +397,15 @@ PostgreSQL documentation
> > > >           Multiple tables can be vacuumed by writing multiple
> > > >           <option>-t</option> switches.
> > > >          </para>
> > > > +       <para>
> > > > +        If no tables are specified with the <option>--table</option> option,
> > > > +        <application>vacuumdb</application> will clean all regular tables
> > > > +        and materialized views in the connected database.
> > > > +        If <option>--analyze-only</option> or
> > > > +        <option>--analyze-in-stages</option> is also specified,
> > > > +        it will analyze all regular tables, partitioned tables,
> > > > +        and materialized views (but not foreign tables).
> > > > +       </para>
> > >
> > > I suggest replacing "clean" with "process", since VACUUM does so much more than
> > > clean up dead tuples.
> >
> > I see your point. However, since the vacuumdb docs already use "clean"
> > in several places, I think it's better to keep using "clean" here
> > for consistency. Thought?
>
> Works for me; I didn't consider that.
>
> > > Concerning backpatching, I voted against, but I suggest that this be backpatched
> > > to v18.  I don't feel very strongly about it though.
> >
> > As for back-patching, I failed to find a strong reason to apply this change
> > to v18 over the many other patches that could not be committed before
> > the feature freeze... Of course if there's broad support for back-patching,
> > we can certainly revisit it. But for now I'm thinking to commit the patch
> > to master.
>
> I don't have a strong reason either - my reasoning was that the change is small
> and unlikely to introduce a bug, and that it would be nice to get more accurate
> statistics on partitioned tables after "pg_upgrade" a year earlier.
>
> But I won't object if the patch is only in v19.

OK, so for now I've pushed the patch to master. Thanks!

Regards,

-- 
Fujii Masao

  27. Re: analyze-in-stages post upgrade questions

    Laurenz Albe <laurenz.albe@cybertec.at> — 2025-08-20T07:14:20Z

    On Wed, 2025-08-20 at 13:31 +0900, Fujii Masao wrote:
> OK, so for now I've pushed the patch to master. Thanks!

Thank you for working on that!

Yours,
Laurenz Albe

  28. Re: analyze-in-stages post upgrade questions

    Justin Pryzby <pryzby@telsasoft.com> — 2025-08-21T01:51:16Z

    When analyzing a partitioned table, I think you should use ANALYZE ONLY,
or otherwise avoid processing the children twice.

Thanks for handling this.  I was recently suprised to learn that
vacuumdb doesn't process parents.

-- 
Justin

  29. Re: analyze-in-stages post upgrade questions

    Justin Pryzby <pryzby@telsasoft.com> — 2026-06-04T17:14:34Z

    Checking back.

On Wed, Aug 20, 2025 at 08:51:16PM -0500, Justin Pryzby wrote:
> When analyzing a partitioned table, I think you should use ANALYZE ONLY,
> or otherwise avoid processing the children twice.
> 
> Thanks for handling this.  I was recently suprised to learn that
> vacuumdb doesn't process parents.