[FEATURE REQUEST] Dynamic histogram-query-times

[dusatvoj]

Hello, I have set up log_min_duration_statement to 1000, bcs I only care about long queries to be optimized. But there are only 2 bars used at index.html#histogram-query-times.
It would be great to make this graph dynamic (like when there's no query with less than X milliseconds there will be generated graph with diferrent scale) or to specify manually the minimum (it it would make more sense, but I'm not sure about it.

Thank you