Re: Optimize kernel readahead using buffer access strategy

On Sun, Nov 17, 2013 at 11:02 PM, KONDO Mitsumasa
<kondo.mitsumasa@lab.ntt.co.jp> wrote:
>>> However, my patch is on the way and needed to more improvement. I am
>>> going
>>> to add method of controlling readahead by GUC, for user can freely select
>>> readahed parameter in their transactions.
>>
>>
>> Rather, I'd try to avoid fadvising consecutive or almost-consecutive
>> blocks. Detecting that is hard at the block level, but maybe you can
>> tie that detection into the planner, and specify a sequential strategy
>> when the planner expects index-heap correlation?
>
> I think we had better to develop these patches in step by step each patches,
> because it is difficult that readahead optimizetion is completely come true
> from a beginning of one patch. We need flame-work in these patches, first.

Well, problem is, that without those smarts, I don't think this patch
can be enabled by default. It will considerably hurt common use cases
for postgres.

But I guess we'll have a better idea about that when we see how much
of a performance impact it makes when you run those tests, so no need
to guess in the dark.