To use MySQL workbench through ssh tunnel, you just need to create a new connection in the workbench, and then choose "Standard TCP/IP over SSH" for the "connection method".
Every webapp in Google Apps Script must have a main function called doGet() which is the entry point of the app, the function that your app will start with when you type the webapp url. This is true for every application deployed as a standalone app and called by its url - with a user interface or not. If you read the documentation you'll see that all the standalone apps examples for HTMLService or UiApp have a doGet function. Only container embedded ui scripts or scripts that run on triggers are not concerned by this rule.
'Creating sort index' is the database figuring out the order of the returned values based on ‘order by’ clause. Main resources limit here would be available CPU and memory. The sort won't be done until the data is already all in memory if the result is small. Adding suitable index could make the query faster.
Programs written in Java are faster than other popular languages like Python Java is more widely used in commercial applications as compared to other programming languages like Python and hence integrating Selenium tests it easier