Re: multicolumn index and setting effective_cache_size using human-readable-numbers

On 29 February 2016 at 18:31, Joshua D. Drake <jd@commandprompt.com> wrote:
> I haven't been following this thread but did you try looking at the costs?

Thanks for the response...

> #seq_page_cost = 1.0                    # measured on an arbitrary scale
> #random_page_cost = 4.0                 # same scale as above
> #cpu_tuple_cost = 0.01                  # same scale as above
> #cpu_index_tuple_cost = 0.005           # same scale as above
> #cpu_operator_cost = 0.0025             # same scale as above
> #effective_cache_size = 128MB
>
> Especially seq_page_cost, random_page_cost and cpu_index_tuple_cost?

seq_page_cost: 1
random_page_cost: 4
cpu_tuple_cost: 0.01
cpu_index_tuple_cost: 0.005
cpu_operator_cost: 0.0025
effective_cache_size: 3GB

I'm not really sure what changes I could make that would make one
index that's ostensibly equivalent to the other not be attractive to
the planner though. I can mess with those figures but as I said before
the only one that flicks the switch is to change effective_cache_size
to 8GB, which makes no sense to me.

Geoff