Re: CommitDelay performance improvement

ncm(at)zembu(dot)com (Nathan Myers) writes:
>> Comments? What should the threshold N be ... or do we need to make
>> that a tunable parameter?

> Once you make it tuneable, you're stuck with it. You can always add
> a knob later, after somebody discovers a real need.

If we had a good idea what the default level should be, I'd be willing
to go without a knob. I'm thinking of a default of about 5 (ie, at
least 5 other active backends to trigger a commit delay) ... but I'm not
so confident of that that I think it needn't be tunable. It's really
dependent on your average and peak transaction lengths, and that's
going to vary across installations, so unless we want to try to make it
self-adjusting, a knob seems like a good idea.

A self-adjusting delay might well be a great idea, BTW, but I'm trying
to be conservative about how much complexity we should add right now.

regards, tom lane