summarize could show min/max times and other useful stats.

[eddyb]

We're investigating a case where a query is taking 30-40ms on average, but by using crox we can see instances of that query being over 200ms sometimes, with the maximum around 330ms.

Would be nice to get this information from summarize itself.

[theotherphil]

I'd like to have a go at this, if it's not particularly time sensitive.

[michaelwoerister]

A related question to @Mark-Simulacrum: Will perf.rlo crash if new columns are added or will it just ignore them?

[michaelwoerister]

@theotherphil Feel free to give it a try!

[Mark-Simulacrum]

I'm not sure what you mean by columns. I expect no - perf.rlo parses JSON summaries with serde and iirc doesn't prohibit unknown fields and such, though it may come down to the specifics of the data format. I don't expect problems though.

[michaelwoerister]

With "column" I mean something that could end up as a new column in the detailed view table, so in practice a new field in summarize's QueryData struct.

I gave it a try earlier and, as you say, serde_json seems to handle unknown fields just fine: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=4c8b1574ce2e46c4e4687d88e7938c98

[theotherphil]

I've just had a look at this.

I want to start by adding min and max, to get the wiring sorted before I worry about the overhead of tracking the state required to compute percentiles.

I'm a bit stuck at the very first hurdle: I'm not sure how to recognise a complete logical event in the event data. Specifically, I'm not sure what relationship is guaranteed between QUERY_EVENT_KIND, INCREMENTAL_LOAD_RESULT_EVENT_KIND and QUERY_BLOCKED_EVENT_KIND events in rustc's self-profiler output. #104 adds the time from incremental cache loading and blocked queries to the self time for each event label. Should I attempt to group consecutive events with different kinds but matching labels, or just ignore the latter two event kinds?

[michaelwoerister]

@theotherphil Each event is self-contained. For min/max you can just compare Event::timestamps. I would not make a distinction between the different event kinds.