* Tom Lane (t...@sss.pgh.pa.us) wrote: > Joel Jacobson <j...@trustly.com> writes: > > We already have xact_start, query_start and backend_start > > to get the timestamptz for when different things happened. > > > I would like to propose adding a fourth such column, "waiting_start", > > which would tell how long time a backend has been waiting. > > The difficulty with that is it'd require a gettimeofday() call for > every wait start. Even on platforms where those are relatively cheap, > the overhead would be nasty --- and on some platforms, it'd be > astonishingly bad. We sweated quite a lot to get the overhead of > pg_stat_activity wait monitoring down to the point where it would be > tolerable for non-heavyweight locks, but I'm afraid this would push > it back into the not-tolerable range.
Could we handle this like log_lock_waits..? Thanks! Stephen
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