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Re: [HACKERS] wal buffers documentation -errata

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Dave Cramer <pg(at)fastcrypt(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: [HACKERS] wal buffers documentation -errata
Date: 2007-01-20 21:44:27
Message-ID: 200701202144.l0KLiRK14762@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
I have applied the attached patches to CVS HEAD and 8.2.X to mention
defaults that match the contents of postgresql.conf.  I also added a
mention that pg_settings.unit shows the default units for a setting.

One problem is that some settings use a default unit of seconds, but the
default value is one minute, or "1m".  shared_buffers has a similar
problem, using 8k blocks as the default unit, but having a default value
of 32MB or similar.  

I am unsure how we can really improve this.  Saying the default units
are measured in seconds, but the default value is 1 minute is pretty
confusing.  Hopefully the pg_settings.unit mention will help, and users
will always use units for fields that have them in postgresql.conf.

I have added lines documenting the memory and time units to
postgresql.conf. Hopefully that will help too.

---------------------------------------------------------------------------

Dave Cramer wrote:
> 
> On 11-Jan-07, at 12:49 PM, Tom Lane wrote:
> 
> > Dave Cramer <pg(at)fastcrypt(dot)com> writes:
> >> the point is that the documentation suggests that the default is 8
> >> not 8MB, but 8, when in fact the defaults are now given in memory
> >> units not pages
> >
> > Oh, I thought you were complaining that the value was numerically  
> > wrong.
> >
> > Perhaps we should convert the documentation to show the defaults in a
> > units-ified way, but if so it needs to be done consistently.  Most of
> > the entries seem not to have been changed; for example shared_buffers
> > is still described in blocks.
> 
> Yes, everything is described in blocks, but in the configuration file  
> everything (I've looked at so far) is specified in memory units.
> While I appreciate the effort that went into making it somewhat  
> easier to use memory units I can see this being very confusing for  
> the average user.
> 
> I would suggest that the documentation needs to be consistent with  
> the example configuration file installed by initdb
> 
> Dave
> >
> > 			regards, tom lane
> >
> > ---------------------------(end of  
> > broadcast)---------------------------
> > TIP 7: You can help support the PostgreSQL project by donating at
> >
> >                 http://www.postgresql.org/about/donate
> >
> 
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Have you searched our list archives?
> 
>                http://archives.postgresql.org

-- 
  Bruce Momjian   bruce(at)momjian(dot)us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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