Hello, team!

Today I bumped into issue of now knowing how exactly data from history_uint table is used. As per talk with colleagues, there are unverified information what after 4h data from history table aggregated to trends table.
In some circumstances history data is used for graphs rendering, and in some only trends data used (I guess big period of rendering triggers that behavior) disregarding availability of history data, here is a quote from IRC by Gleb:
"I noticed it when I was preparing my workshop. Even when I had history stored for a century, frontend tried to seek for trends (and couldn't find any)."

Could you please write a documentation on these points?

• when and how exactly trends data is filled?
• what are places where raw history_uint data is used?
• how graphs are rendered?
• based on information for graphs rendering and history_uint usage, could you provide any recommendations on history keeping period for integer values?