Explanation
When using the CURRENT_ROLE and CURRENT_USER functions with secure views that will be shared to other Snowflake accounts, Snowflake returns a NULL value for these functions. The reason is that the owner of the data being shared does not typically control the users or roles in the account with which the view is being shared.

Explanation
For some operations (e.g. duplicate elimination for a huge data set), the amount of memory available for the compute resources used to execute the operation might not be sufficient to hold intermediate results. As a result, the query processing engine will start spilling the data to local disk. If the local disk space is not sufficient, the spilled data is then saved to remote disks.
This spilling can have a profound effect on query performance (especially if remote disk is used for spilling).
To alleviate this, It is recommend that:
Using a larger warehouse (effectively increasing the available memory/local disk space for the op-eration), and/or Processing data in smaller batches.

Explanation
Query Profile, available through the classic web interface, provides execution details for a query. For the selected query, it provides a graphical representation of the main components of the pro-cessing plan for the query, with statistics for each component, along with details and statistics for the overall query.
Query Profile is a powerful tool for understanding the mechanics of queries. It can be used whenev-er you want or need to know more about the performance or behavior of a particular query. It is de-signed to help you spot typical mistakes in SQL query expressions to identify potential performance bottlenecks and improvement opportunities.