How do I know if the number of files are causing performance issues?

[User16826992666]

I have read and heard that having too many small files can cause performance problems when reading large data sets. But how do I know if that is an issue I am facing?

[sajith_appukutt]

Databricks SQL endpoint has a query history section which provides additional information to debug / tune queries. One such metric under execution details is the number of files read. 

For ETL/Data science workloads, you could use the Spark UI of the cluster and click on "Query Details" to get this info.