This is really up to you, though I would avoid detaching unless absolutely necessary. Opening and closing a PersistenceManager should be extremely cheap (it's instantiating a PersistenceManagerFactory that's expensive). You've got a few options here, and what you do really just depends on what makes sense for you:
- dependency inject the PersistenceManager into a DAO class that you instantiate and pass that instance around, closing it when you are complete - open and close each time in the DAO - the problem here is if you need a PersistenceManager that spans DAO objects (either build that into a method or a Service layer, though for the record I have an aversion to additional, unnecessary layers that do a single thing) >From a performance perspective, we aren't doing anything. If you take a look at the low-level API documentation, there's no concept of "close": http://code.google.com/appengine/docs/java/javadoc/com/google/appengine/api/datastore/package-summary.html On Wed, Feb 10, 2010 at 8:26 AM, hsjawanda <hsjawa...@gmail.com> wrote: > Nobody knows the answer to this? > > On Feb 7, 2:34 pm, hsjawanda <hsjawa...@gmail.com> wrote: > > Should the PersistenceManager be closed after every query? > > > > I have a utility class that handles querying the datastore. This class > > then returns results which are used by JSP pages to show output. > > > > AFAIK, these are my options: > > > > * Make all my data objects detachable (what is the extra cost of doing > > this? Don't they have to be copied when detaching? > > ) > > * Make a second call on the utility class to close the PM (defeats the > > purpose of having the utility class) > > > > * Leave my PM unclosed (what is/are the implications of this?) > > > > I am referring to a case where I am only doing reads from the data > > store. > > > > Regards, > > Harshdeep > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To post to this group, send email to > google-appengine-j...@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. > > -- Ikai Lan Developer Programs Engineer, Google App Engine http://googleappengine.blogspot.com | http://twitter.com/app_engine -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
