Jamie Thomson on 25 Mar 2015 14:58:26
Please download this .pbix: http://1drv.ms/19kbMxs, open it and try and load data into the reports (you will need to create a data source setting for http://sqlblog.com in order to do so). It takes quite a long time to run so please be patient.
The query attempts to load data from http://sqlblog.com, it does so by getting a list of bloggers from this blogging site, then iterating over them and requesting more information from the site for each one.
Notice that the last step in the query adds a field called "YearMonth". With this step as part of the query the query ends after it has returned data for 10 bloggers. If you then remove that step and load the query then it loads data for all bloggers on the http://sqlblog.com.
My complaint is that I have absolutely no idea why adding the YearMonth column causes considerably less data to be returned. I am assuming that an error has occurred somewhere but here's the problem, I *simply do not know what has gone wrong*. Powerquery does not provide any insights whatsoever into what is going on under the hood. There is no activity log (that I am aware of) that allows me to diagnose what the problem is here.
This submission is not a request for you to tell me what is wrong with the above .pbix. It is a request to provide more information within PowerQuery to power users (which I consider myself to be) so that we can understand more about what is going on under the hood when a query runs, and thus give us the ability to diagnose problems like this.