Frontend: Parameter 'LogQueriesLongerThan' does not behave as described in the docs

[matej-g]

Hello 👋

At Thanos, we have noticed that the LogQueriesLongerThan does not behave as is described in the docs:
Log queries that are slower than the specified duration. Set to 0 to disable. Set to < 0 to enable on all queries.

In particular, setting the parameter to < 0 does not make it to log all queries, it actually disables logging (quick glance at the code seem to confirm this).

What is the correct way to handle this? Should the functionality be adjusted to adhere to the docs or should the docs be amended to describe current behavior?

[alanprot]

I think it may be ok to change the behavior to log everything if < 0 as the default value is 0 and anybody that changed this to be < 0 was trying to enable the logs on all queries. Thoughts @alvinlin123 @bboreham ?

[alvinlin123]

Yes I agree, this sounds like a bug and we should fix the code to do what document says.

[matej-g]

Thanks for chiming in, a opened a quick PR to fix this #4633.

[bboreham]

I think the reason this was missed is that the people who wanted the detail also added -frontend.query-stats-enabled, and that logs everything. Ref #3939

[alanprot]

Gotcha... So what you recommend? Change the query-stats-enabled to be subject to LogQueriesLongerThan and fix the LogQueriesLongerThan behaviour? I think the main thing about query-stats-enabled is to return the stats info in the response header, not to log the queries itself, so maybe they should just be unrelated nobs.