Charting over 1000 data points

I'm certainly unlucky, but I've yet to succeed once in creating a semantic graph. For example failures of the simple histogram kind, see [1] and [2].

I've tried many tweaks by following docs for different formats and suggestions by Special:Ask itself, but the outcome is always the same:

1. either a graph is shown based on a random subset of the data points (i.e. completely false);
2. or no graph is shown at all (sometimes a helpful message "The chart or graph is empty due to missing data" is shown instead).

Now, I understand there is a limit in how resource-intensive a graph can be, but the docs (here or on mw.o) don't even mention this error at all. Example questions I'd like the docs to answer:

1. how many data points you can reasonably expect to succeed in charting;
2. whether increasing the semantic results limit in wiki configuration helps, or any other configuration tweak is possible;
3. if some of the chart formats is more likely to succeed;
4. whether I can exclude there are errors in my query where the same query succeeds in other formats (e.g. standard count or list);
5. if there is some way to optimise the queries so that some data is sent to the format;
6. how to make the chart display some error or footnote or whatever when some data was skipped;
7. how to break down a chart in multiple charts which don't fail.

Nemo bis (talk)