Re: Add min and max execute statement time in pg_stat_statement

On Wed, Oct 23, 2013 at 4:51 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
> No, I'm not. I'm suggesting storing the query texts externally, in a
> file. They usually use 1024 bytes of shared memory per entry,
> regardless of how long the query text is.

I should add that I think that that's about the useful limit of such
schemes. Maybe we could buy a bit more breathing room by storing some
of the stats externally, but I doubt it'd be worth it. I'm not
interested in optimizing pg_stat_statements in the direction of
supporting aggregating a number of distinct entries past much more
than 10,000. I am interested in making it store richer statistics,
provided we're very careful about the costs. Every time those counters
are incremented, a spinlock is held. I don't want everyone to have to
pay any non-trivial additional cost for that, given that the added
instrumentation may not actually be that useful to most users who just
want a rough picture.

--
Peter Geoghegan