> I sometimes find myself, in code, wanting to create a database, or more > specifically test if a database exists and create it if does not. The > database module appears not have functions to create (or delete databases). > Is this a deliberate design decision?
Indeed it is; but we are still looking for a good solution to fill this obvious gap. Even if databases are pretty light-weight entities in BaseX, the creation of a new database within an XQuery expression may trigger numerous side effects related to other database operations. The main reason for that is the functional nature of XQuery and the "pending update list" of XQuery Update: all updating commands will become effective after the query itself has been evaluated. However, commands like db:add() or db:delete() commands will (currently) only end up on the list if the addressed database already exists. Another example: db:create() could overwrite a database that already existed, and some commands would possibly refer to the old instance, while other updating commands would access the new one. One general solution to this challenge would be the XQuery Scripting Extension [1], which allows you to execute commands sequentially (i.e., in an imperative manner). XQSE is definitely on our list, but which will require considerable time to realize -- mainly because a straightforward implementation would sabotage many of the existing functional optimizations in the code (some of the functional and imperative optimizations are even diametrical). In summary, I cannot give a satifsying answer yet except for the advice to use the BaseX commands, REST or XQJ (via XQExpression.executeCommand()), but I'm very open to ideas and proposals how to tackle this challenge. Christian [1] http://www.w3.org/TR/xquery-sx-10/ _______________________________________________ BaseX-Talk mailing list [email protected] https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk
