Dataflow Gen2 Very Slow to Preview Oracle On Premises Data

[kdoherty]

I find that the data preview in Power Query for Dataflows Gen2 is very slow to populate when connecting to on premises Oracle database.  Small tables (1000 rows) take 4+ minutes to populate preview.  

Is this a common experience?  

Thank you.

Kevin Doherty

[miguel]

This is not the expected experience, but it also depends on a number of factors such as your network, the data source, and our service. 

I'd recommend reaching out to our support team so they can do a more thorough investigation to see what could be happening and why it takes so long to query the data.

[kdoherty · Accepted solution]

The issue I experienced was due to an Advance Option I had turned on in the Power Query builder.

Include Relationship Columns - this being one cause many additional columns of type Table to be added to the query.  Once I turned this off, data preview is much better.

Thank you.

[kdoherty]

Thank you.   I will contact support.