Strange bars with increase function

[Manish G]

I have a query on increase function.

What is good value ot be used as time window? Issue is that I use 60m window, and the bar graph I get is not of distinct rectangular bars, but instead something like this

Is this expected?

My metrics is a counter, so for a window of 60 min query must calculate a single value, and create a rectangular bar whose base length represents 60 min and height represents represent calculated value, and I must see a series of such well defined rectangles.