Power Query Diagnostics - What does "Generate Preview" mean?

[lbendlin]

I am trying to diagnose a slow query (merging a CSV source with a SQL source) and can't really understand what the diagnostics is telling me.  Any idea what Power Query is doing when it creates a preview?

[v-eachen-msft]

Hi @lbendlin ,

Here is an official document about "Query Diagnostics" feature in power query. You could refer to it:

https://docs.microsoft.com/en-us/power-query/querydiagnostics