Re: shared-memory based stats collector

On 07/06/2018 12:34 PM, Robert Haas wrote:
> On Fri, Jul 6, 2018 at 3:02 PM, Joshua D. Drake <jd@commandprompt.com> wrote:
>> Will stats, if we move toward the suggested changes be "less" accurate than
>> they are now? We already know that stats are generally not accurate but they
>> are close enough. If we move toward this change will it still be close
>> enough?
> There proposed change would have no impact at all on the long-term
> accuracy of the statistics.  It would just mean that there would be
> race conditions when reading them, so that for example you would be
> more likely to see a count of heap scans that doesn't match the count
> of index scans, because an update arrives in between when you read the
> first value and when you read the second one.  I don't see that
> mattering a whole lot, TBH, but maybe I'm missing something.

I agree that it probably isn't a big deal. Generally speaking when we 
look at stats it is to get an "idea" of what is going on. We don't care 
if we are missing an increase/decrease of 20 of any particular value 
within stats. Based on this and what Andres said, it seems like a net 
win to me.

JD

>

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