Heatmap data needs to be optimized

[silverwind]

A regular page load is about 30-40ms rendering time but any page containing heatmap data like the homepage, drastically increases page rendering time to around 200-400ms. We should find ways to optimize this.

[lunny]

Does #23574 resolve this partially?

[silverwind]

No that is unrelated. The problem with heatmap data, IIRC is both that the backend database query is expensive (primary issue), and that the JSON format that is dumped into the HTML is inefficient.

[lunny]

Since it's by day, maybe we can store the result in some table.

[silverwind]

Some form of cache would be needed I guess. Note that users can push commits for previous or even future dates, so it would have to be invalidated on every user push.

[lafriks]

We do not show commits in heatmap but only user actions so they can be only with current date not in the past or future.

Previously when I implemented it it was returning data already summed up by day but it was reworked later on to return all data to fronted to account user timezone

[silverwind]

Data format is currently

[{"timestamp":1657821600,"contributions":1}]

It could at least be minified to

[[1657821600,1]]

Still I think real performance increase can only come from some form of caching.

[lunny]

Duplicate of #29769 since more discussion there.