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* doc: alter table references bogus table-specific planner parameters
@ 2020-01-06 02:56 Justin Pryzby <pryzby@telsasoft.com>
0 siblings, 1 reply; 4+ messages in thread
From: Justin Pryzby @ 2020-01-06 02:56 UTC (permalink / raw)
To: pgsql-hackers@lists.postgresql.org; +Cc: Simon Riggs <simon@2ndQuadrant.com>
commit 6f3a13ff058f15d565a30c16c0c2cb14cc994e42 Enhance docs for ALTER TABLE lock levels of storage parms
Author: Simon Riggs <simon@2ndQuadrant.com>
Date: Mon Mar 6 16:48:12 2017 +0530
<varlistentry>
<term><literal>SET ( <replaceable class="PARAMETER">storage_parameter</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )</literal></term>
...
- Changing fillfactor and autovacuum storage parameters acquires a <literal>SHARE UPDATE EXCLUSIVE</literal> lock.
+ <literal>SHARE UPDATE EXCLUSIVE</literal> lock will be taken for
+ fillfactor and autovacuum storage parameters, as well as the
+ following planner related parameters:
+ effective_io_concurrency, parallel_workers, seq_page_cost
+ random_page_cost, n_distinct and n_distinct_inherited.
effective_io_concurrency, seq_page_cost and random_page_cost cannot be set for
a table - reloptions.c shows that they've always been RELOPT_KIND_TABLESPACE.
n_distinct lock mode seems to have been changed and documented at e5550d5f ;
21d4e2e2 claimed to do the same, but the LOCKMODE is never used.
See also:
commit 21d4e2e20656381b4652eb675af4f6d65053607f Reduce lock levels for table storage params related to planning
Author: Simon Riggs <simon@2ndQuadrant.com>
Date: Mon Mar 6 16:04:31 2017 +0530
commit 47167b7907a802ed39b179c8780b76359468f076 Reduce lock levels for ALTER TABLE SET autovacuum storage options
Author: Simon Riggs <simon@2ndQuadrant.com>
Date: Fri Aug 14 14:19:28 2015 +0100
commit e5550d5fec66aa74caad1f79b79826ec64898688 Reduce lock levels of some ALTER TABLE cmds
Author: Simon Riggs <simon@2ndQuadrant.com>
Date: Sun Apr 6 11:13:43 2014 -0400
commit 2dbbda02e7e688311e161a912a0ce00cde9bb6fc Reduce lock levels of CREATE TRIGGER and some ALTER TABLE, CREATE RULE actions.
Author: Simon Riggs <simon@2ndQuadrant.com>
Date: Wed Jul 28 05:22:24 2010 +0000
commit d86d51a95810caebcea587498068ff32fe28293e Support ALTER TABLESPACE name SET/RESET ( tablespace_options ).
Author: Robert Haas <rhaas@postgresql.org>
Date: Tue Jan 5 21:54:00 2010 +0000
Justin
Attachments:
[text/x-diff] v1-0001-Fixes-for-commit-6f3a13ff.patch (0B, ../../20200106025623.GA12066@telsasoft.com/2-v1-0001-Fixes-for-commit-6f3a13ff.patch)
download
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: doc: alter table references bogus table-specific planner parameters
@ 2020-01-06 03:48 Simon Riggs <simon@2ndquadrant.com>
parent: Justin Pryzby <pryzby@telsasoft.com>
0 siblings, 1 reply; 4+ messages in thread
From: Simon Riggs @ 2020-01-06 03:48 UTC (permalink / raw)
To: Justin Pryzby <pryzby@telsasoft.com>; +Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
On Mon, 6 Jan 2020 at 02:56, Justin Pryzby <pryzby@telsasoft.com> wrote:
> commit 6f3a13ff058f15d565a30c16c0c2cb14cc994e42 Enhance docs for ALTER
> TABLE lock levels of storage parms
> Author: Simon Riggs <simon@2ndQuadrant.com>
> Date: Mon Mar 6 16:48:12 2017 +0530
>
> <varlistentry>
> <term><literal>SET ( <replaceable
> class="PARAMETER">storage_parameter</replaceable> = <replaceable
> class="PARAMETER">value</replaceable> [, ... ] )</literal></term>
> ...
> - Changing fillfactor and autovacuum storage parameters acquires a
> <literal>SHARE UPDATE EXCLUSIVE</literal> lock.
> + <literal>SHARE UPDATE EXCLUSIVE</literal> lock will be taken for
> + fillfactor and autovacuum storage parameters, as well as the
> + following planner related parameters:
> + effective_io_concurrency, parallel_workers, seq_page_cost
> + random_page_cost, n_distinct and n_distinct_inherited.
>
> effective_io_concurrency, seq_page_cost and random_page_cost cannot be set
> for
> a table - reloptions.c shows that they've always been
> RELOPT_KIND_TABLESPACE.
>
Right, but if they were settable at table-level, the lock levels shown
would be accurate.
I agree with the sentiment of the third doc change, but your patch removes
the mention of n_distinct, which isn't appropriate.
The second change in your patch alters the meaning of the sentence in a way
that is counter to the first change. The name of these parameters is
"Storage Parameters" (in various places); I might agree with describing
them in text as "storage or planner parameters", but if you do that you
can't then just refer to "storage parameters" later, because if you do it
implies that planner parameters operate differently to storage parameters,
which they don't.
> n_distinct lock mode seems to have been changed and documented at e5550d5f
> ;
> 21d4e2e2 claimed to do the same, but the LOCKMODE is never used.
>
But neither does it need to because we don't lock tablespaces.
Thanks for your comments.
--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/;
PostgreSQL Solutions for the Enterprise
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: doc: alter table references bogus table-specific planner parameters
@ 2020-01-06 04:13 Justin Pryzby <pryzby@telsasoft.com>
parent: Simon Riggs <simon@2ndquadrant.com>
0 siblings, 1 reply; 4+ messages in thread
From: Justin Pryzby @ 2020-01-06 04:13 UTC (permalink / raw)
To: Simon Riggs <simon@2ndquadrant.com>; +Cc: pgsql-hackers@lists.postgresql.org
On Mon, Jan 06, 2020 at 03:48:52AM +0000, Simon Riggs wrote:
> On Mon, 6 Jan 2020 at 02:56, Justin Pryzby <pryzby@telsasoft.com> wrote:
>
> > commit 6f3a13ff058f15d565a30c16c0c2cb14cc994e42 Enhance docs for ALTER TABLE lock levels of storage parms
> > Author: Simon Riggs <simon@2ndQuadrant.com>
> > Date: Mon Mar 6 16:48:12 2017 +0530
> >
> > <varlistentry>
> > <term><literal>SET ( <replaceable
> > class="PARAMETER">storage_parameter</replaceable> = <replaceable
> > class="PARAMETER">value</replaceable> [, ... ] )</literal></term>
> > ...
> > - Changing fillfactor and autovacuum storage parameters acquires a
> > <literal>SHARE UPDATE EXCLUSIVE</literal> lock.
> > + <literal>SHARE UPDATE EXCLUSIVE</literal> lock will be taken for
> > + fillfactor and autovacuum storage parameters, as well as the
> > + following planner related parameters:
> > + effective_io_concurrency, parallel_workers, seq_page_cost
> > + random_page_cost, n_distinct and n_distinct_inherited.
> >
> > effective_io_concurrency, seq_page_cost and random_page_cost cannot be set
> > for
> > a table - reloptions.c shows that they've always been
> > RELOPT_KIND_TABLESPACE.
>
> I agree with the sentiment of the third doc change, but your patch removes
> the mention of n_distinct, which isn't appropriate.
I think it's correct to remove n_distinct there, as it's documented previously,
since e5550d5f. That's a per-attribute option (not storage) and can't be
specified there.
<varlistentry>
<term><literal>SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )</literal></term>
<term><literal>RESET ( <replaceable class="PARAMETER">attribute_option</replaceable> [, ... ] )</literal></term>
<listitem>
<para>
This form sets or resets per-attribute options. Currently, the only
...
+ <para>
+ Changing per-attribute options acquires a
+ <literal>SHARE UPDATE EXCLUSIVE</literal> lock.
+ </para>
> The second change in your patch alters the meaning of the sentence in a way
> that is counter to the first change. The name of these parameters is
> "Storage Parameters" (in various places); I might agree with describing
> them in text as "storage or planner parameters", but if you do that you
> can't then just refer to "storage parameters" later, because if you do it
> implies that planner parameters operate differently to storage parameters,
> which they don't.
The 2nd change is:
for details on the available parameters. Note that the table contents
- will not be modified immediately by this command; depending on the
+ will not be modified immediately by setting its storage parameters; depending on the
parameter you might need to rewrite the table to get the desired effects.
I deliberately qualified that as referring only to "storage params" rather than
"this command", since planner params never "modify the table contents".
Possibly other instances in the document (and createtable) should be changed
for consistency.
Justin
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: doc: alter table references bogus table-specific planner parameters
@ 2020-01-06 04:33 Simon Riggs <simon@2ndquadrant.com>
parent: Justin Pryzby <pryzby@telsasoft.com>
0 siblings, 0 replies; 4+ messages in thread
From: Simon Riggs @ 2020-01-06 04:33 UTC (permalink / raw)
To: Justin Pryzby <pryzby@telsasoft.com>; +Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
On Mon, 6 Jan 2020 at 04:13, Justin Pryzby <pryzby@telsasoft.com> wrote:
>
> > I agree with the sentiment of the third doc change, but your patch
> removes
> > the mention of n_distinct, which isn't appropriate.
>
> I think it's correct to remove n_distinct there, as it's documented
> previously,
> since e5550d5f. That's a per-attribute option (not storage) and can't be
> specified there.
>
OK, then agreed.
> The second change in your patch alters the meaning of the sentence in a
> way
> > that is counter to the first change. The name of these parameters is
> > "Storage Parameters" (in various places); I might agree with describing
> > them in text as "storage or planner parameters", but if you do that you
> > can't then just refer to "storage parameters" later, because if you do it
> > implies that planner parameters operate differently to storage
> parameters,
> > which they don't.
>
> The 2nd change is:
>
> for details on the available parameters. Note that the table
> contents
> - will not be modified immediately by this command; depending on the
> + will not be modified immediately by setting its storage parameters;
> depending on the
> parameter you might need to rewrite the table to get the desired
> effects.
>
> I deliberately qualified that as referring only to "storage params" rather
> than
> "this command", since planner params never "modify the table contents".
> Possibly other instances in the document (and createtable) should be
> changed
> for consistency.
>
Yes, but it's not a correction, just a different preference of wording.
--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/;
PostgreSQL Solutions for the Enterprise
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2020-01-06 02:56 doc: alter table references bogus table-specific planner parameters Justin Pryzby <pryzby@telsasoft.com>
2020-01-06 03:48 ` Simon Riggs <simon@2ndquadrant.com>
2020-01-06 04:13 ` Justin Pryzby <pryzby@telsasoft.com>
2020-01-06 04:33 ` Simon Riggs <simon@2ndquadrant.com>
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