I'm considering the idea of creating a persistent storage like a dbms engine, what would be the benefits to create a custom binary format over directly cPickling the object and/or using the shelve module? ...
First of all I'll explain the question. By persistence, I mean storing data beyond the execution of a single request. It might not be the best question title, so feel free to edit it. The way I see it, there are three types of persistence in GAE, each one "closer" to the request itself: The datastore This is where all data is most l...
Hi Can someone please advise on how to define & map (using annotations) custom types in Hibernate? Eg, given: @Entity public class Line { private Point startPoint; private Point endPoint; } public class Point { private double x; private double y; } Rather than having Point persisted as an object, I'd like to see Lin...
I am just getting into Grails having had some experience with Rails, and I am looking at creating an app where I have to primarily persist tree structures (and query them as well). Rails has several very useful acts_as helpers for representing domain objects as different data structures, such as acts_as_tree. From my initial reading it ...
I have a servlet calling a session bean via a local interface. There is a 3 second pause between the last statement of the session method and the statement following that method call in the servlet. I have identified what statement in the session bean causes the extra delay upon method return, but I just have no idea why there is such ...
I am interested in developing a portal-based application that works with EAV models and would like to know if there are any Java frameworks that aid in this type of development? salesforce.com uses EAV and currently has twenty tables. The framework I seek should allow it to be configurable to different EAV implementations ...
Hi, everybody. I have this problem for a long time now, I have searched the web and SO in and out and didn't find a solution yet. I hope you can help me on that. I have a parent-child relationship between two entities like the following: @Entity public class Parent { // ... @OneToMany(mappedBy = "parent", fetch = FetchType.LA...
What is the best persistence API for use with GWT? Sadly, the application will be hosted on my own java server, as I will need more control than GAE will give me. I know I will need to have two sets of my entities, one for the server side, and some pojo's for the client side. I'm looking to make the mapping of the data as simple as...
I'm writing a tutorial on Rebol's Object persistence but I'm not sure if my way is the best suppose %config.txt contains a: 1 b: 2 We can then load it with config: construct load %config.txt To save it back to file I use this save %config.txt (pick to-block mold config 3) But I'm not sure this is the most elegant syntax to do ...
I'm using Hibernate backed JPA as my persistence layer. I have a multi-threaded process that aggregates data from a Soap call and then stores a row in a database. The process usually ends up inserting about 700 rows and takes about 1 - 3 hours, with the Soap calls being the main bottleneck. During this entire process the table I am ins...
how to make it so that the table user_roles defines the two columns (userID, roleID) as a composite primary key. should be easy, just can't remember/find. in userdao @ManyToMany(fetch = FetchType.LAZY) @JoinTable(name = "user_roles") public List<RoleDAO> getRoles() { return roles; } @Id @GeneratedValue(strategy = ...
I'm using oracle10g database and eclipselink, I need to obtain the last inserted key from the table so i've created this query javax.persistence.Query q = em.createQuery("SELECT nvl(MAX(c.myAtt),0) " + "from myTable as c"); return Integer.parseInt(q.getSingleResult().toS...
I have a UITableView which displays two different entity types -- each row could be either EntityA or EntityB. cellForRowAtIndexPath looks at the class type and determines how to create the cell. I am persisting my objects using Core Data and would like to use a fetchedResultsController to manage this tableview because of the memory-man...
The Java JCR API defines a persistence mechanism which can be used to replace many of the traditional roles of a RDBMS. For example, JackRabbit - the JCR reference implementation - supports transactions, SQL queries, object-content mapping, etc. You could pick one or the other, storing binary data in BLOBs/file system pointers in a RDBM...
I have an app that is running in the simulator. I read and write from a sqlite3 data source. However, if i restart the app, then all datg that i had previously wrote to the db is lost. The data is always in its original state. Now back when i was developing this app i thought i read somewhere that data can not be persisted via iphone si...
I have a dialog box with a bunch of dimensions that a user can change by moving/dragging, including a JTable with resizable/draggable columns. What I would like to do is to make the state of these resizable columns / dialog boxes / etc. persistent, so the next time my application starts up, the user doesn't have to go through the resizi...
So, I want to store a dictionary in a persistent file. Is there a way to use regular dictionary methods to add, print, or delete entries from the dictionary in that file? It seems that I would be able to use cPickle to store the dictionary and load it, but I'm not sure where to take it from there. ...
I'm starting on a new scientific project which has a lot of data (millions of entries) I'd like to store in an easily and quickly accessible format. I've come across a number of different potential options, but I'm not sure how to pick amongst them. My data can probably just be stored as a dictionary, or potentially a dictionary of dicti...
I programmed a simple WCF service that stores messages sent by users and sends these messages to the intended user when asked for. For now, the persistence is implemented by creating username.xml files with the following structure: <messages recipient="username"> <message sender="otheruser"> ... </message </messages> It is po...
Hi all, Considering Hibernate 3, I have a parent table, and a child table, linked by a foreign key. I declare a many-to-one association into parent hbm file with a cascade all property. I first persit a parent (save or persist) and it saves a parent and a child. Fine so far. But in another session, i create a new parent object (functi...