I blog about it really before here, but in a colorful discussion on twitter after they closed this bug report, (Max rows in PowerBI is 30 K), I recalled a bug report about R ggplot, when the authors suggested to use multi points instead of individual points to speed the plotting of the map !!! all I had to do is to check if icon map support it and it did !!!.
WKT format for point is POINT (x,y), all you need to do is to concatenate multiple rows of point in MULTIPOINT format MULTIPOINT ((x y),(x1 y1), etc).
now we need to deal with three thing:
1-The maximum row numbers returned to a visual is 30K.
2-The maximum length of a column in PowerQuery is 32766
3-The Maximum length of DAX function is 2.1 Million
so a calculated column is a no go, I am using this DAX measure to concatenate the text from (x y) to a Multipoint format, again using Chris blog, I got this measure
WKT = var concat =CONCATENATEX(values(openstreetmap[point]),openstreetmap[point],",") var wkt ="MULTIPOINT ("&concat&")"return if (concat =BLANK(),BLANK(),wkt)
using this table that contains all the items tagged as amenity in Openstreet Map, the table contain 17 Million records, got it from BigQuery dataset
remember you don’t want to group all points in 1 row for two reason.
1- Concatenax Max is 2.1 Million
2-it is better still to group by common attribute, at you can color code for example by country or category or both if you want, in this case, I added a third factor in MULTIPOINTS, just a number that change very 30k rows to make sure I will not end up with a multipoints > 2.1 million, Initially It was 100K, but I notice icon map become extremely slow
now in icon Map, you need to assign three fields.
Category : multipoints
Icon URL/WKT/SVG: the measure wkt, this extremely clever and flexible, as it is a measure, that will render using the filter context of category, you may want to be creative and implement drill using different level of details, as the geometry is calculated on the fly.
Circle/line/WKT/Geojson Outline Color : a color in hex format, in my case, coded by country, ( at work for a different use case, I use a measure instead to show change of status per time)
because, the data set is relative big, I use this option in PowerBI
Just to be clear, this only proof of concept, rendering a big dataset will be slow and will eat all your memory, and probably you will get errors in shared workspace, or if you are in a premium workspace, probably you will end up in a trouble, but it is cool, personnaly, I use it to render a 58K points and it is very smoth.
anyway here is the result filtering the tag place of worship 1.1 Million, I tried parking which is 3.2 Million but my laptop crashed !!!, I know it is subjective, but that looks very beautiful for me.
here tag : School and University color by Country
edit : got a nice feedback from Reddit user data_Crucher, just to improve the performance I materialized the results using a calculated table, the drawback is you increase the size of the model, but I guess it is worth it, and I changed the decimal precision for the lat and long to 4 digits just to reduce the size, the pbix is around 600 MB.
again for production scenarios, I think around 100K points should be doable.