Peter Geoghegan <p...@bowt.ie> writes: > On Wed, Apr 24, 2019 at 2:15 PM Joe Conway <m...@joeconway.com> wrote: >> Has anyone ever (or recently) measured the impact on performance to have >> this enabled? Is it that generically useful for debugging of production >> instances of Postgres that we really want it always enabled despite the >> performance impact?
> It is disabled by default, in the sense that the trace_sort GUC > defaults to off. I believe that the overhead of building in the > instrumentation without enabling it is indistinguishable from zero. It would probably be useful to actually prove that rather than just assuming it. I do see some code under the symbol that is executed even when !trace_sort, and in any case Andres keeps complaining that even always-taken branches are expensive ... > In > any case the current status quo is that it's built by default. I have > used it in production, though not very often. It's easy to turn it on > and off. Would any non-wizard really have a use for it? It seems like we should either make this really a developer option (and hence not enabled by default) or else move it into some other category than DEVELOPER_OPTIONS. regards, tom lane