persistence

I am struggling to apprehend the slight differences between the hibernate methods saveOrUpdate - update - save/persist . I know there are some similar questions on the site: What are the differences between the different saving methods in Hibernate? Difference between save and saveOrUpdate method hibernate but having read them, I did not notice an answer covering all the issues coming from using those methods in any case. I would to mention the example I have created to test: I have a table USER with the records: id | company 1 Company1 2 Company2 I execute then the code: Session session =

Using a DB with C++ is a real mess and it was refreshing when I moved to Java to be able to use a unified system to abstract the whole layer away (aka Hibernate). There are a couple of C++ abstract layers for DB's out there but they are usually vendor specific and only a thin layer that wraps the real C API. Has anybody come across something more like hibernate for C++ or know of a group or open source project that is looking at this problem domain. I don't know of any C++ library like Hibernate, but certainly there are non-vendor specific libs: SOCI and DTL We developed an open source library

I have an expensive function that takes and returns a small amount of data (a few integers and floats). I have already memoized this function, but I would like to make the memo persistent. There are already a couple of threads relating to this, but I'm unsure about potential issues with some of the suggested approaches, and I have some fairly specific requirements: I will definitely use the function from multiple threads and processes simultaneously (both using multiprocessing and from separate python scripts) I will not need read or write access to the memo from outside this python function I

When using SQLite I usually have a single SQLiteOpenHelper instance per application and I never ever close it, since its database is used continuously by many other classes and closing/reopening it would be slower and more complicated. Now I'm toying with Realm and I'm planning to access Realm instances only from Data Access Objects. Every call will be made from a worker thread. I've been reading the examples and they usually call getInstance/close per Activity or background task. Since Realm persists the data in a file like SQLite, is it a good idea to call getInstance/close for each

I'm writing a reasonably complex web application. The Python backend runs an algorithm whose state depends on data stored in several interrelated database tables which does not change often, plus user specific data which does change often. The algorithm's per-user state undergoes many small changes as a user works with the application. This algorithm is used often during each user's work to make certain important decisions. For performance reasons, re-initializing the state on every request from the (semi-normalized) database data quickly becomes non-feasible. It would be highly preferable,