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Run-Length Encoding in Power BI

Chris Webb performs some experiments:

Recently I was involved in an interesting discussion on Twitter X about how partitioning a table in a Power BI dataset semantic model can affect compression and therefore its size and query performance. You can read the thread here. It got me thinking: is there a way to get more detail on how well compression, and in particular run-length encoding (RLE from hereon), is working for a column when you’re using Import mode or Direct Lake? After a bit of research I found out there is, so let’s see some examples that illustrate what I learned.

The results are interesting and Chris explains why we see what we do.