wal buffers documentation -errata

Dave Cramer <pg@fastcrypt.com> writes:

However I just loaded up an 8.2.1 and the default is 32m

Then you changed it in postgresql.conf. I get

$ psql
Welcome to psql 8.2.1, the PostgreSQL interactive terminal.

Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit

regression=# show wal_buffers ;
wal_buffers
-------------
64kB
(1 row)

regression=#

regards, tom lane

Tom,

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

Dave
On 11-Jan-07, at 10:09 AM, Tom Lane wrote:

Dave Cramer <pg@fastcrypt.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.

regards, tom lane

On 11-Jan-07, at 12:49 PM, Tom Lane wrote:

Dave Cramer <pg@fastcrypt.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

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@fastcrypt.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@momjian.us
EnterpriseDB http://www.enterprisedb.com

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