Add graph for daily downloads

[bruno-garcia]

Currently we only have a ever growing graph.
The feature request is to add a second graph that will show the number of downloads for a time period.

Matthias' request: https://twitter.com/matkoch87/status/1225797785313796099

[michael-hawker]

My SQL is rusty, it seems like this is where the data is grabbed from the DB:

nuget-trends/src/NuGetTrends.Data/NuGetTrendsContextExtensions.cs

Lines 20 to 33 in 4209af5

	const string sql = @"
	SELECT AVG(COALESCE(d.download_count, NULL)) AS download_count,
	DATE_TRUNC('day', (totalPeriod.day + CAST((-CAST(FLOOR(DATE_PART('dow', totalPeriod.day)) AS integer) || ' days') AS interval))) AS week
	FROM
	(
	SELECT day
	FROM generate_series(
	DATE_TRUNC('day', (NOW() AT TIME ZONE 'UTC' + CAST((-@months || ' months') AS interval)))
	, DATE_TRUNC('day', (NOW() AT TIME ZONE 'UTC'))
	, interval '1 day') AS t(day)
	) AS totalPeriod
	LEFT JOIN daily_downloads AS d ON totalPeriod.day = d.date AND d.package_id = @packageId
	GROUP BY week
	ORDER BY week;";

Does the DB have the raw download data per day or is it stored in aggregate form already?

[joaopgrassi]

@michael-hawker the data is stored per day, in the daily_downloads table. We do it by hitting the NuGet API daily for all stored packages we have.