| From: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
|---|---|
| To: | Mike Ivanov <mikei(at)activestate(dot)com> |
| Cc: | Sean Ma <seanxma(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: random slow query |
| Date: | 2009-06-30 18:06:33 |
| Message-ID: | dcc563d10906301106n5335d5e6r8a2faf7467c942b8@mail.gmail.com |
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| Lists: | pgsql-performance |
On Tue, Jun 30, 2009 at 12:01 PM, Mike Ivanov<mikei(at)activestate(dot)com> wrote:
> Scott Marlowe wrote:
>>>
>>> The postgres shared cache is at 4G, is that too big?
>>>
>>
>> Not for a machine with 32Gig of ram.
>>
>>
>
> He could even add some more.
Definitely. Really depends on how big his data set is, and how well
pgsql is at caching it versus the kernel. I've found that with a
really big dataset, like 250G to 1T range, the kernel is almost always
better at caching a lot of it, and if you're operating on a few
hundred meg at a time anyway, then smaller shared_buffers helps.
OTOH, if you're working on a 5G data set, it's often helpful to turn
up shared_buffers enough to cover that.
OTOH, if you're running a busy transaction oriented db (lots of small
updates) larger shared_buffers will slow you down quite a bit.
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