In this first part I’m going to set up the scenario and show you what I found out from my own experimentation. The really mind-blowing tricks shown to me by the ever-helpful Curt Hagenlocher of the Power Query dev team will be covered in part 2.
Let’s say you have a large csv file which contains a numeric column and you want to get the maximum value from that column. In this case I’m going to use the 2018 Price Paid data from the UK Land Registry available here. This csv file contains 1021215 rows, one for each property transaction in England and Wales in 2018; the second column in this file contains the the price paid for the property, so the aim here is to get the maximum price paid for all property transactions in 2018.
Read the whole thing.