Re: WIP patch for hint bit i/o mitigation

On Fri, Jan 18, 2013 at 5:34 AM, Craig Ringer <craig(at)2ndquadrant(dot)com> wrote:
> On 12/14/2012 09:57 PM, Amit Kapila wrote:
>>>
>>> I need to validate the vacuum results. It's possible that this is
>>> solvable by tweaking xmin check inside vacuum. Assuming that's fixed,
>>> the question stands: do the results justify the change? I'd argue
>>> 'maybe'
>> We can try with change (assuming change is small) and see if the performance
>> gain is good, then discuss whether it really justifies.
>> I think the main reason for Vacuum performance hit is that in the test pages
>> are getting dirty only due to setting of hint bit
>> by Vacuum.
>>
>>> -- I'd like to see the bulk insert performance hit reduced if
>>> possible.
>> I think if we can improve performance for bulk-insert case, then this patch
>> has much more value.
> Has there been any movement in this - more benchmarks and data showing
> that it really does improve performance, or that it really isn't helpful?

Atri is working on that. I don't know if he's going to pull it out
though in time so we may have to pull the patch from this fest. My
take on the current patch is that the upside case is pretty clear but
the bulk insert performance impact needs to be figured out and
mitigated (that's what Atri is working on).

merlin