Re: Changing the random_page_cost default (was: cpu_tuple_cost)

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Josh Berkus wrote:
> I don't agree. The defaults are there for people who aren't going to read
> enough of the documentation to set them. As such, conservative for the
> defaults is appropriate.

Sure, but I would argue that 4 is *too* conservative. We've certainly changed
other values over the years. I see it as those most affected by this change
are those who are least likely to have the know-how to change the default,
and are also the majority of our users. I've often had to reduce this, working
on many databases, on many versions of PostgreSQL. Granted, I don't work on
any huge, complex, hundreds of gig databases, but that supports my point -
if you are really better off with a /higher/ (than 3) random_page_cost, you
already should be tweaking a lot of stuff yourself anyway. Tom Lane has a
good point about tweaking other default parameters as well, and that's a
worthy goal, but I don't think extended searching for a "sweet spot" should
prevent us from making a small yet important (IMO!) change in the default
of this one variable.

N.B. My own personal starting default is 2, but I thought 3 was a nice
middle ground more likely to reach consensus here. :)

- --
Greg Sabino Mullane greg(at)turnstep(dot)com
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http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8
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