Re: testing HS/SR - 1 vs 2 performance

On Mon, Apr 12, 2010 at 7:07 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Mon, Apr 12, 2010 at 5:06 AM, Fujii Masao <masao.fujii@gmail.com> wrote:
>> On Sat, Apr 10, 2010 at 8:23 AM, Erik Rijkers <er@xs4all.nl> wrote:
>>> I understand that in the scale=1000 case, there is a huge
>>> cache effect, but why doesn't that apply to the pgbench runs
>>> against the standby?  (and for the scale=10_000 case the
>>> differences are still rather large)
>>
>> I guess that this performance degradation happened because a number of
>> buffer replacements caused UpdateMinRecoveryPoint() often. So I think
>> increasing shared_buffers would improve the performance significantly.
>
> I think we need to investigate this more.  It's not going to look good
> for the project if people find that a hot standby server runs two
> orders of magnitude slower than the primary.
As a data point, I did a read only pgbench test and found that the
standby runs about 15% slower than the primary with identical hardware
and configs.
>
> ...Robert
>
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--
--
Jim Mlodgenski
EnterpriseDB (http://www.enterprisedb.com)