On 2023-03-07 13:43:28 -0500, Melanie Plageman wrote: > > Now I've a second thought: what do you think about resetting the related > > number > > of operations and *_time fields when enabling/disabling track_io_timing? > > (And mention it in the doc). > > > > That way it'd prevent bad interpretation (at least as far the time per > > operation metrics are concerned). > > > > Thinking that way as we'd loose some (most?) benefits of the new *_time > > columns > > if one can't "trust" their related operations and/or one is not sampling > > pg_stat_io frequently enough (to discard the samples > > where the track_io_timing changes occur). > > > > But well, resetting the operations could also lead to bad interpretation > > about the operations... > > > > Not sure about which approach I like the most yet, what do you think? > > Oh, this is an interesting idea. I think you are right about the > synchronization issues making the statistics untrustworthy and, thus, > unuseable.
No, I don't think we can do that. It can be enabled on a per-session basis. I think we simply shouldn't do anything here. This is a pre-existing issue. I also think that loosing stats when turning track_io_timing on/off would not be helpful. Greetings, Andres Freund
