pg.ddx.io pgsql-performance@postgresql.org mailing list archive
help / color / mirror / Atom feedInterpreting shared_buffers setting
6+ messages / 4 participants
[nested] [flat]
* Interpreting shared_buffers setting
@ 2019-01-29 12:32 Bob Jolliffe <bobjolliffe@gmail.com>
0 siblings, 3 replies; 6+ messages in thread
From: Bob Jolliffe @ 2019-01-29 12:32 UTC (permalink / raw)
To: pgsql-performance@lists.postgresql.org
Excuse me if this is a silly question. I am trying to fiddle with
shared_buffers setting on postgresql 10.6 on ubuntu 18.04 server.
I have this at bottom of my config file:
shared_buffers = 1GB
Yet when I check the setting from pg_setting I see something quite different:
postgres=# SELECT name, setting FROM pg_settings where name = 'shared_buffers';
name | setting
----------------+---------
shared_buffers | 131072
Is this a question of units? It looks like 128M. Note when I change
the setting to 2GB in conf file I see 262144 from pg_setting. I am
now unsure what the actual shared_buffers allocation is. I cant see
anything in the docs which tells me how to interpret the integer.
Any clarification welcome.
Regards
Bob
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Interpreting shared_buffers setting
@ 2019-01-29 12:35 Thomas Markus <t.markus@proventis.net>
parent: Bob Jolliffe <bobjolliffe@gmail.com>
2 siblings, 0 replies; 6+ messages in thread
From: Thomas Markus @ 2019-01-29 12:35 UTC (permalink / raw)
To: pgsql-performance@lists.postgresql.org
Hi,
check for blocksize (8k) as factor.
8k*131072=1G
regards
Thomas
Am 29.01.19 um 13:32 schrieb Bob Jolliffe:
> Excuse me if this is a silly question. I am trying to fiddle with
> shared_buffers setting on postgresql 10.6 on ubuntu 18.04 server.
>
> I have this at bottom of my config file:
> shared_buffers = 1GB
>
> Yet when I check the setting from pg_setting I see something quite different:
>
> postgres=# SELECT name, setting FROM pg_settings where name = 'shared_buffers';
> name | setting
> ----------------+---------
> shared_buffers | 131072
>
> Is this a question of units? It looks like 128M. Note when I change
> the setting to 2GB in conf file I see 262144 from pg_setting. I am
> now unsure what the actual shared_buffers allocation is. I cant see
> anything in the docs which tells me how to interpret the integer.
>
> Any clarification welcome.
>
> Regards
> Bob
>
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Interpreting shared_buffers setting
@ 2019-01-29 13:07 Andrew Gierth <andrew@tao11.riddles.org.uk>
parent: Bob Jolliffe <bobjolliffe@gmail.com>
2 siblings, 1 reply; 6+ messages in thread
From: Andrew Gierth @ 2019-01-29 13:07 UTC (permalink / raw)
To: Bob Jolliffe <bobjolliffe@gmail.com>; +Cc: pgsql-performance@lists.postgresql.org
>>>>> "Bob" == Bob Jolliffe <bobjolliffe@gmail.com> writes:
Bob> Excuse me if this is a silly question. I am trying to fiddle with
Bob> shared_buffers setting on postgresql 10.6 on ubuntu 18.04 server.
Bob> I have this at bottom of my config file:
Bob> shared_buffers = 1GB
Bob> Yet when I check the setting from pg_setting I see something quite
Bob> different:
Bob> postgres=# SELECT name, setting FROM pg_settings where name = 'shared_buffers';
Bob> name | setting
Bob> ----------------+---------
Bob> shared_buffers | 131072
pg_settings can tell you more than you asked for:
postgres=# select * from pg_settings where name='shared_buffers';
-[ RECORD 1 ]---+-------------------------------------------------------------
name | shared_buffers
setting | 16384
unit | 8kB
category | Resource Usage / Memory
short_desc | Sets the number of shared memory buffers used by the server.
extra_desc |
context | postmaster
vartype | integer
source | configuration file
min_val | 16
max_val | 1073741823
enumvals |
boot_val | 1024
reset_val | 16384
sourcefile | /home/andrew/work/pgsql/inst/9.5/data/postgresql.conf
sourceline | 113
pending_restart | f
notice that "unit 8kB" line; the displayed integer value is in units of
8kB (which is the block size your server was compiled with, which you
can also see as the block_size parameter).
--
Andrew (irc:RhodiumToad)
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Interpreting shared_buffers setting
@ 2019-01-29 15:42 Bob Jolliffe <bobjolliffe@gmail.com>
parent: Andrew Gierth <andrew@tao11.riddles.org.uk>
0 siblings, 0 replies; 6+ messages in thread
From: Bob Jolliffe @ 2019-01-29 15:42 UTC (permalink / raw)
To: pgsql-performance@lists.postgresql.org
Thank you Andrew and Thomas. All is now clear :-)
On Tue, 29 Jan 2019 at 13:07, Andrew Gierth <andrew@tao11.riddles.org.uk> wrote:
>
> >>>>> "Bob" == Bob Jolliffe <bobjolliffe@gmail.com> writes:
>
> Bob> Excuse me if this is a silly question. I am trying to fiddle with
> Bob> shared_buffers setting on postgresql 10.6 on ubuntu 18.04 server.
>
> Bob> I have this at bottom of my config file:
> Bob> shared_buffers = 1GB
>
> Bob> Yet when I check the setting from pg_setting I see something quite
> Bob> different:
>
> Bob> postgres=# SELECT name, setting FROM pg_settings where name = 'shared_buffers';
> Bob> name | setting
> Bob> ----------------+---------
> Bob> shared_buffers | 131072
>
> pg_settings can tell you more than you asked for:
>
> postgres=# select * from pg_settings where name='shared_buffers';
> -[ RECORD 1 ]---+-------------------------------------------------------------
> name | shared_buffers
> setting | 16384
> unit | 8kB
> category | Resource Usage / Memory
> short_desc | Sets the number of shared memory buffers used by the server.
> extra_desc |
> context | postmaster
> vartype | integer
> source | configuration file
> min_val | 16
> max_val | 1073741823
> enumvals |
> boot_val | 1024
> reset_val | 16384
> sourcefile | /home/andrew/work/pgsql/inst/9.5/data/postgresql.conf
> sourceline | 113
> pending_restart | f
>
> notice that "unit 8kB" line; the displayed integer value is in units of
> 8kB (which is the block size your server was compiled with, which you
> can also see as the block_size parameter).
>
> --
> Andrew (irc:RhodiumToad)
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Interpreting shared_buffers setting
@ 2019-01-29 18:31 Jerry Sievers <gsievers19@comcast.net>
parent: Bob Jolliffe <bobjolliffe@gmail.com>
2 siblings, 1 reply; 6+ messages in thread
From: Jerry Sievers @ 2019-01-29 18:31 UTC (permalink / raw)
To: Bob Jolliffe <bobjolliffe@gmail.com>; +Cc: pgsql-performance@lists.postgresql.org
Bob Jolliffe <bobjolliffe@gmail.com> writes:
> Excuse me if this is a silly question. I am trying to fiddle with
> shared_buffers setting on postgresql 10.6 on ubuntu 18.04 server.
>
> I have this at bottom of my config file:
> shared_buffers = 1GB
>
> Yet when I check the setting from pg_setting I see something quite different:
>
> postgres=# SELECT name, setting FROM pg_settings where name = 'shared_buffers';
> name | setting
> ----------------+---------
> shared_buffers | 131072
Why not use the show command which is good about output in human
terms...
psql (11.1 (Ubuntu 11.1-1.pgdg16.04+1))
Type "help" for help.
meta_a:postgres# select name, setting from pg_settings where name = 'shared_buffers');
ERROR: syntax error at or near ")"
LINE 1: ...me, setting from pg_settings where name = 'shared_buffers');
^
meta_a:postgres#
>
> Is this a question of units? It looks like 128M. Note when I change
> the setting to 2GB in conf file I see 262144 from pg_setting. I am
> now unsure what the actual shared_buffers allocation is. I cant see
> anything in the docs which tells me how to interpret the integer.
>
> Any clarification welcome.
>
> Regards
> Bob
>
>
--
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres.consulting@comcast.net
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Interpreting shared_buffers setting
@ 2019-01-29 18:40 Jerry Sievers <gsievers19@comcast.net>
parent: Jerry Sievers <gsievers19@comcast.net>
0 siblings, 0 replies; 6+ messages in thread
From: Jerry Sievers @ 2019-01-29 18:40 UTC (permalink / raw)
To: Jerry Sievers <gsievers19@comcast.net>; +Cc: Bob Jolliffe <bobjolliffe@gmail.com>; pgsql-performance@lists.postgresql.org
Jerry Sievers <gsievers19@comcast.net> writes:
> Bob Jolliffe <bobjolliffe@gmail.com> writes:
>
>> Excuse me if this is a silly question. I am trying to fiddle with
>> shared_buffers setting on postgresql 10.6 on ubuntu 18.04 server.
>>
>> I have this at bottom of my config file:
>> shared_buffers = 1GB
>>
>> Yet when I check the setting from pg_setting I see something quite different:
>>
>> postgres=# SELECT name, setting FROM pg_settings where name = 'shared_buffers';
>> name | setting
>> ----------------+---------
>> shared_buffers | 131072
Aaaaay! Pasted junk... Here's what I meant.
meta_a:postgres# select setting from pg_settings where name='shared_buffers';
setting
---------
131072
(1 row)
meta_a:postgres# show shared_buffers;
shared_buffers
----------------
1GB
(1 row)
>
> Why not use the show command which is good about output in human
> terms...
>
> psql (11.1 (Ubuntu 11.1-1.pgdg16.04+1))
> Type "help" for help.
>
> meta_a:postgres# select name, setting from pg_settings where name = 'shared_buffers');
> ERROR: syntax error at or near ")"
> LINE 1: ...me, setting from pg_settings where name = 'shared_buffers');
> ^
> meta_a:postgres#
>
>>
>> Is this a question of units? It looks like 128M. Note when I change
>> the setting to 2GB in conf file I see 262144 from pg_setting. I am
>> now unsure what the actual shared_buffers allocation is. I cant see
>> anything in the docs which tells me how to interpret the integer.
>>
>> Any clarification welcome.
>>
>> Regards
>> Bob
>>
>>
--
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres.consulting@comcast.net
^ permalink raw reply [nested|flat] 6+ messages in thread
end of thread, other threads:[~2019-01-29 18:40 UTC | newest]
Thread overview: 6+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2019-01-29 12:32 Interpreting shared_buffers setting Bob Jolliffe <bobjolliffe@gmail.com>
2019-01-29 12:35 ` Thomas Markus <t.markus@proventis.net>
2019-01-29 13:07 ` Andrew Gierth <andrew@tao11.riddles.org.uk>
2019-01-29 15:42 ` Bob Jolliffe <bobjolliffe@gmail.com>
2019-01-29 18:31 ` Jerry Sievers <gsievers19@comcast.net>
2019-01-29 18:40 ` Jerry Sievers <gsievers19@comcast.net>
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox