Re: Performance features the 4th

Christopher Browne wrote:

> A long time ago, in a galaxy far, far away, pgman(at)candle(dot)pha(dot)pa(dot)us (Bruce Momjian) wrote:
>> Tom Lane wrote:
>>> Jan Wieck <JanWieck(at)Yahoo(dot)com> writes:
>>> > As a matter of fact, people who have performance problems are likely to
>>> > be the same who have upgrade problems. And as Gaetano pointed out
>>> > correctly, we will see wildforms with one or the other feature applied.
>>>
>>> I'd believe that for patches of the size of my original VACUUM-delay
>>> hack (or even a production-grade version of same, which'd probably be
>>> 10x larger). The kind of wholesale rewrite you are currently proposing
>>> is much too large to consider folding back into 7.4.*, IMHO.
>>
>> What Jan could do is to have a 7.4 patch available that people can test,
>> and he can improve it during the 7.5 development cycle with feedback
>> from users.
>
> The thing is, there are two patches that seem likely to be of
> interest:
>
> a) There's the ARC changes, which really feel like they are 7.5
> development, not likely to be readily backportable;
>
> b) On the other hand, a "simple delay" on the VACUUM seems likely
> to be useful, and reasonably backportable.
>
> And these are two quite different things, both of which may be worth
> having.

I only need to know the three W's, when, what and where (when do people
want what pieces of the stuff where?).

However, I have not seen much evidence yet that the vacuum delay alone
does that much. In conjunction with putting vacuum dirtied blocks at LRU
instead of MRU maybe, but that's again another functional change. So I
am not sure what the outcome of that for 7.4 is. The general opinion is
that the whole thing is too much. But nobody has done anything to show
how the vacuum delay alone compares to that.

Jan

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