On 10/09/2013 07:58 AM, Bruce Momjian wrote:
But it still is an independent parameter. I am just changing the default.
maintenance_work_mem can depend on work_mem ~ work_mem * 1 * max_connection / 4
That is kind of hard to do because we would have to figure out if the
old maintenance_work_mem was set from a default computation or by the
user.
FYI, this auto-tuning is not for us, who understand the parameters and
how they interact, but for the 90% of our users who would benefit from
better defaults. It is true that there might now be cases where you
would need to _reduce_ work_mem from its default, but I think the new
computed default will be better for most users.
Just to step in here as a consultant. Bruce is right on here. Autotuning
has nothing to do with us, it has to do with Rails developers who deploy
PostgreSQL and known nothing of it except what ActiveRecord tells them
(I am not being rude here).
We could argue all day what the best equation is for this, the key is to
pick something reasonable, not perfect.
Joshua D. Drake
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