Re: [DOCS] [ADMIN] shared_buffers and shmmax

[Tom Lane]

[ redirecting to pgsql-docs ]

Valentin Bogdanov <[EMAIL PROTECTED]> writes:
>> From: dx k9 <[EMAIL PROTECTED]>
>> I'm trying to understand what the documentation means
>> by bytes per increment, what is the increment supposed to
>> be bytes, MB, or Kb.

> shared_buffers is in disk block size, typically 8K, at least that's what it 
> is on Linux platforms. shmmax is quite simply in bytes.

The table the OP is looking at (table 17.2 in the 8.3 docs) predates
the ability to specify shared_buffers in KB or MB instead of
number-of-buffers.  I agree it's not entirely obvious that what it
means is "multiply your setting in KB/MB by 8400/8192".  Anybody have
an idea how to clarify things?

regards, tom lane

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Re: [DOCS] [ADMIN] shared_buffers and shmmax

[Francisco Reyes]

On 10:45 am 07/22/08 Tom Lane <[EMAIL PROTECTED]> wrote:
> [ redirecting to pgsql-docs ]
> number-of-buffers.  I agree it's not entirely obvious that what it
> means is "multiply your setting in KB/MB by 8400/8192".  Anybody have
> an idea how to clarify things?


Perhaps changing the table title?
Table 17-2. Configuration parameters affecting PostgreSQL's shared memory
usage when not using a size modified.

Alternatively, below the table we could have clarifications such as:
Previously, it was not possible to indicate a size modified such as M for
Megabytes. As of version X.Y, Postgresql allows to use M, for MB, GB for GB
and more... See for all values.

When not using one of the new modifiers the space used would be the number
you enter times the constant on the right side of the table.
For example using 100 shared_buffers would be 100 x 8400  = 840,000 bytes.


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