Accumulating lists in Power Query using… List.Acculumate()

List.Accumulate is a very powerful function that is often overlooked, when doing Power Query transformations. Its basic behaviour is explained in the reference. How this function works is accumulates a result from a specified operation (accumulator function) starting from the initial value – seed – and going row by row till the end of a specified list. Radacad greatly explained the possibilities of the function. I treat List.Accumulate as a function that lets me access a previous row. Something that is very often expected by customers using Excel sheets as data sources. This enables me to e.g. detect a change in ID or date – from my experience 90% of the cases.

Authenticating to a datasource with multiple credentials

The case from one of my previous comments had another catch! As I mentioned the client was downloading data from an API. The client was interested in data for multiple entities i.e. had to use different credentials for the same URL to retrieve different datasets. Because the client wanted to see everything in one Power BI I had to find a suitable solution. Same as before, I turned my attention towards M language!

Flights during a storm

This vizualization took way more time than I expected. The idea came up on 29th June, when I was sitting in Microsoft’s office right next to the airport in Warsaw. The storm during that afternoon was huge. I immediately checked flightradar24 to see, what the airtraffic looks like. I wondered what it would look like if plotted with the clouds and maps.

Delete from FTP using Azure Data Factory

During development of an ETL process in Azure Data Factory, you may come across a need to delete the data from FTP. It may be neccessary e.g. when you want to make place for new incoming data or you don’t want your pipeline to pull the old data twice. The solution of the problem lays in a custom activity.