Re: PostgreSQL on RAM Disk / tmpfs

On Aug 3, 2006, at 1:26 PM, Merlin Moncure wrote:

> On 8/2/06, Thomas F. O'Connell <tfo@sitening.com> wrote:
>> I'm working on a postgres instance (8.1.2 running on Solaris 10)
>> where the
>> data directory (including WAL) is being mounted on tmpfs. Based on
>> this, and
>> with knowledge that fsync is disabled, I'm operating under the
>> assumption
>> that recoverability is not a precondition for optimized
>> performance. With
>> that assumption, I have several questions, some performance-
>> related, others
>> internals-related:
>
> to be honest, I think the best approach is to simply write to the
> traditional filesystem and leave fsync off.  writing to a ramdisk
> might be a bit faster, but you deprive the server memory from doing
> other things like caching and sorting.  this might be more true for
> some o/s than others though.  i'm just curious, what led you to do
> ramdisk implementation  (most people who ask questions about ramdisk
> have no idea what they are talking about, although you seem to).

That was how I found it. :)

I think, though, that it was the result of benchmarking a variety of
on-disk RAID configurations with an eye toward ever increasing write
throughput.

>> 4. Considering that recoverability is not a precondition, is there
>> an easy
>> patch that could be applied to the 8.1.x series from 8.1.4 on that
>> would
>> allow disabling full_page_writes? For a database in RAM with high
>> write
>> volume, is this setting even likely to make a difference?
>
> I would suggest pulling 8.2dev (shortly beta) if you want this and
> experiment. it is perfectly stable.  looking at the todo list, 8.2
> also gets the multiple insert syntax, which is nice.
>
> if have super high write volumes, consider writing your insert call in
> C. prepare your statement, and use the parameterized
> version....ExecPrepared(...).

Can you point to a good example of this anywhere in the docs? I don't
see ExecPrepared anywhere in the core documentation.

--
Thomas F. O'Connell
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