Forum Discussion
Slow performance within Power BI Desktop, Query editor, Applied Steps.
I am having the same issue. I am making simple updates in Query Editor, formatting data in 1 specific column and it could take hours for it to me done.
It seems that the speed has declined with each new version of PowerBI.
I think you have a good point about the number of steps within a query.
I definitely need a resolution soon.
Cheryl, South Florida
Not a solution, but some discussion. Power Query is very aggressive about reloading the query preview. It seems that each additional step can result in re-reading the source and re-applying intermediate steps. If you have expensive query steps or a large data source, I've seen this slowdown. With well-optimized transformations and sufficient disk throughput, I don't see this sort of slowdown.
I've experienced 2 types of slowness:
1) When editing the query
2) When executing
When doing multiple steps the editing can be slower than the execution itselft. So what I'm doing in these cases is to insert a temporary date-filter as one of the 1st steps which I later remove. This keeps the editing process quick.
For certain operations it can also help to use Table.Buffer or List.Buffer: In order to prevent that the same query will be executed multiple times. But as this will prevent query folding, it can means trial and error to see whether it is actually benefitial.
I don't know if this new option helps with issues like this, but worth testing out against this use case... In the latest update there is a new option you can disable so a preview of data isn't generated on the backend every time you make a change.
Update blog - Look for the Option to disable data previews in the background or it is further explained in the video at 16:40
Can be found in the Desktop under File - Options and Settings - Options - (Current File) - Data Load - Background Data
I took the above suggestions about resolving the performance of query editor. It does not seem to make a difference to filter on a specific date when the query has more than 20 applied steps. Is there a maximum number of applied steps allowed for a query?
There were two steps that I used to speed up the query editor process:
1) Unchecked the "Allow data preview to download in the background." Make sure that this is unchecked in the report view and query editor.
2) The other option that I unchecked was "Enable refresh of this query." This is located in the Query Editor under Properties. DO NOT UNCHECK "Enable load to report."....you will lose the report.
Let me know if this assists anyone or if anyone has other solutions.
Cheryl W.
South Florida
