Re: Performance Improvement by reducing WAL for Update Operation

On 11 January 2013 17:30, Amit kapila <amit.kapila@huawei.com> wrote:
> On Friday, January 11, 2013 7:59 PM Alvaro Herrera wrote:
> Simon Riggs wrote:
>> On 28 December 2012 10:21, Simon Riggs <simon@2ndquadrant.com> wrote:
>>
>
>> I was also worried about the high variance in the results.  Those
>> averages look rather meaningless.  Which would be okay, I think, because
>> it'd mean that performance-wise the patch is a wash,
>
> For larger tuple sizes (>1000 && < 1800), the performance gain will be good.
> Please refer performance results by me and Kyotaro-san in below links:
>
> http://archives.postgresql.org/message-id/6C0B27F7206C9E4CA54AE035729E9C383BEAAE32@szxeml509-mbx
> http://archives.postgresql.org/message-id/20121228.170748.90887322.horiguchi.kyotaro@lab.ntt.co.jp

AFAICS your tests are badly variable, but as Alvaro says, they aren't
accurate enough to tell there's a regression.

I'll assume not and carry on.

(BTW the rejection of the null bitmap patch because of a performance
regression may also need to be reconsidered).

-- Simon Riggs                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services