Re: pg_stat_*_columns?

Andres Freund <andres@anarazel.de> writes:
> On 2015-06-20 10:55:03 -0400, Tom Lane wrote:
>> I dunno that tweaking the format would accomplish much.  Where I'd love
>> to get to is to not have to write the data to disk at all (except at
>> shutdown).  But that seems to require an adjustable-size shared memory
>> block, and I'm not sure how to do that.  One idea, if the DSM stuff
>> could be used, is to allow the stats collector to allocate multiple
>> DSM blocks as needed --- but how well would that work on 32-bit
>> machines?  I'd be worried about running out of address space.

> We could also just mmap() the stats file into memory in various
> processes. With a bit care it should be quite possible to only mmap a
> subsets of the file at once, taking care of the address space issues.

I think we should go into this with the mindset of re-using the DSM
infrastructure, rather than inventing a new mechanism of uncertain
portability.
        regards, tom lane