Custom SQL can have a HUGE impact on the performance of your visuals for the live connections.
If you are using extracts, there will be no impact to the dashboard performance. But, for live connections, Custom SQL can be really deadly
Here is the full recording
Custom SQL can be a nightmare to troubleshoot as well
In general, my guidance is as follows
- AVOID at all costs if your analysis is LIVE against a data source
- AVOID at all costs if your analysis is querying a data source LIVE (oh, I guess I already said that above. Anyway, was worth repeating)
- In the case of extract option, the Custom SQL doesn’t affect your dashboard performance at all but it might impact your extract creation time