Re: Make autovacuum sort tables in descending order of xid_age

> On Mar 30, 2020, at 7:09 AM, David Steele  wrote:
> 
> On 1/11/20 12:53 PM, David Fetter wrote:
>> I agree that it's a complex situation, and that many different
>> approaches will eventually need to be brought to bear.
>> What concerns me about introducing a big lump of complexity here is
>> disentangling the effects of each part and of their interaction terms.
>> We're not, to put it mildly, set up to do ANOVA
>> (https://en.wikipedia.org/wiki/Analysis_of_variance ) , ANCOVA (
>> https://en.wikipedia.org/wiki/Analysis_of_covariance ), etc. on
>> changes.
>> Given the above, I'd like to make the case for changing just this one
>> thing at first and seeing whether the difference it makes is generally
>> positive.
> 
> Mark, Robert, thoughts on this?

I have not been working on this issue lately, but as I recall, my concern was that changing the behavior of autovacuum could introduce regressions for some users, so we should be careful to get it right before we rush to release anything.  It didn't seem like the proposed changes took enough into account.  But that's clearly a judgement call, having to do with how cautious any particular person thinks we should be.  I don't feel strongly enough to stand in the way if the general concensus is that this is a good enough implementation.

—
Mark Dilger
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