sequence

How do I execute multiple servlets in sequence?

Use RequestDispatcher#include() on an URL matching the url-pattern of the Servlet. public class Populate_ALL extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType(“text/plain”); request.getRequestDispatcher(“/populateServlet1”).include(request, response); request.getRequestDispatcher(“/populateServlet2”).include(request, response); request.getRequestDispatcher(“/populateServlet3”).include(request, response); //… } } Note: if those servlets cannot be used independently, then this is the wrong approach and you should be … Read more

Change the name of a key in dictionary

Easily done in 2 steps: dictionary[new_key] = dictionary[old_key] del dictionary[old_key] Or in 1 step: dictionary[new_key] = dictionary.pop(old_key) which will raise KeyError if dictionary[old_key] is undefined. Note that this will delete dictionary[old_key]. >>> dictionary = { 1: ‘one’, 2:’two’, 3:’three’ } >>> dictionary[‘ONE’] = dictionary.pop(1) >>> dictionary {2: ‘two’, 3: ‘three’, ‘ONE’: ‘one’} >>> dictionary[‘ONE’] = … Read more

Hibernate JPA Sequence (non-Id)

Looking for answers to this problem, I stumbled upon this link It seems that Hibernate/JPA isn’t able to automatically create a value for your non-id-properties. The @GeneratedValue annotation is only used in conjunction with @Id to create auto-numbers. The @GeneratedValue annotation just tells Hibernate that the database is generating this value itself. The solution (or … Read more

PostgreSQL gapless sequences

Sequences have gaps to permit concurrent inserts. Attempting to avoid gaps or to re-use deleted IDs creates horrible performance problems. See the PostgreSQL wiki FAQ. PostgreSQL SEQUENCEs are used to allocate IDs. These only ever increase, and they’re exempt from the usual transaction rollback rules to permit multiple transactions to grab new IDs at the … Read more