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Re: Need help in setting optimal configuration for a huge database.

From: Kishore B <kishorebh(at)gmail(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Need help in setting optimal configuration for a huge database.
Date: 2005-10-23 02:05:50
Message-ID: 42567e060510221905t54baa7d4u81cb83a8616a5a99@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-adminpgsql-performance
Hi Gunderson,
 * Can I set the effective_cache_size to 200000?*
* Yes, that should work fine.

* Do you mean that I can set the effective_cache_size to 1.5 GB out of 2GB
Memory that I have in the current system?
 Can I set the sort_memory to 3072? We need to generate reports which make
heavy use of group by and order by clauses.
 Based on the 2GB available memory, how do you want me to Please note
further that we need to execute upto 10 data centric queries at any
instance. Based on these specifications, how do you want me to allocate
memory to the following configuration parameters?
 shared_buffers, (Current Setting : 48000 (375MB))
sort_memory, (Current setting 2048 kb (2MB))
effective_cache_size (Current setting: 100000 (1GB))


 On 10/23/05, Steinar H. Gunderson <sgunderson(at)bigfoot(dot)com> wrote:
>
> [please send replies to the list, not to me directly]
>
> On Sun, Oct 23, 2005 at 03:19:39AM +0530, Kishore B wrote:
> > *You definitely want to upgrade this if you can.
> >
> > > Memory : 2 GB
> > *
> > We can move upto 12 GB if need to be.
>
> I was referring to your PostgreSQL version, not your RAM. More RAM is
> almost
> always an improvement, but for your data set, 2GB sounds quite good. (700k
> rows is not really a "huge database", BTW -- I've seen people here have
> several billion rows a _day_.)
>
> > For now, let us set the configuraiton parameters for 2GB.
> > I failed to mention earlier, that we have a dedicated server for
> database.
> > Can I set the effective_cache_size to 200000?
>
> Yes, that should work fine.
>
> > Can I set the sort_mem size to 4096?
>
> This depends a bit on the queries you're running. Remember that for each
> and
> every sort you do, one of these (measured in 8kB buffers) will get
> allocated.
> Some tuning of your queries against this would probably be useful.
>
> > Will the performance suffer, if I set these parameters too high?
>
> Yes, you can easily run into allocating too much RAM with too high
> sort_mem,
> which could kill your performance. Overestimating effective_cache_size is
> AFAIK not half as bad, though -- it is merely a hint to the planner, it
> does
> not actually allocate memory.
>
> /* Steinar */
> --
> Homepage: http://www.sesse.net/
>
>

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