The queries you see are the test connection pings that you have enabled in the data source creation. Each connection retrieved from the connection pool will be validated by executing the ping query. This is the reason you are seeing the query executed every minute. Also, the ping query is a SQL query executed over the connections returned by the pool of connections to verify that the connection returned is still valid and not stale.
The connections will only be validated if the field “Ping query” contains a query. Otherwise, they will not even if this check box is selected. It is best practice to have them enabled.
To know more about test connections refer to the section ["JDBC Sources"](https://community.denodo.com/docs/html/browse/6.0/vdp/administration/creating_views/importing_data_sources_and_creating_base_views/jdbc_sources#jdbc-sources) of the Virtual DataPort Administration Guide.
Hope this helps.