1. If you just delete all the entities of a single Kind, it is the same effect as deleting a "table". You have to remember that the datastore is not SQL. Underneath the hood, it is a schemaless key-value store. Type information is defined within each entity itself and in the corresponding indexes.
2. The solution that seems to fit for the most developers is to do multiple queries and join in memory. Another solution can be to precompute the result at write time and denormalize your schema so that you query on the denormalized field. Without knowing what you are doing, it can be difficult to recommend any particular workaround. I highly recommend watching the videos from Google I/O and reading the articles to understand how filtering and indexing works. This is a pretty good place to start: http://code.google.com/appengine/articles/datastore/overview.html On Fri, Dec 18, 2009 at 10:12 PM, Bombay Goose <bombaygo...@gmail.com>wrote: > Thanks DataNucleus team and Toby. > > Sorry, but I have some more questions > > 1. How do I delete a particular table dynamically? would just unloading the > class do it? Iin that case, what if there are changes to the dynamic table, > i.e. column addition/dropping, wouldnt that require unloading the class and > hence deletion of table? > 2. I am going through the Queries and Indexes section in the documentation > at > http://code.google.com/appengine/docs/java/datastore/queriesandindexes.html > This section says that inequality operators are allowed only one property. > Is anybody handling a situation where there are multiple properties with > inequality operators? If yes, how have you done it? > Thanks > On Wed, Dec 16, 2009 at 12:18 PM, Toby Reyelts <to...@google.com> wrote: > >> One other thing you might consider is using the native App Engine >> datastore, since it's already schemaless. You can even mix and match using >> the native API and JDO/JPA. >> >> On Wed, Dec 16, 2009 at 1:30 AM, Bombay Goose <bombaygo...@gmail.com>wrote: >> >>> Hello All, >>> >>> I am doing a feasibility study of whether we can develop our application >>> on appengine or not. >>> >>> Our application has a requirement where we have to create tables >>> dynamically, without restarting the application. >>> >>> Is that possible in Appengine? >>> >>> Datanucleus supports this through JDO, with some byte code >>> instrumentation. More info - >>> http://www.jpox.org/servlet/wiki/pages/viewpage.action?pageId=6619188 >>> >>> Is it possible through JPA? if yes, does appengine allow it? >>> if not, does Appengine allow Bytecode instrumentation so that we can >>> create classes dynamically according to the link above using JDO. >>> >>> Any help is greatly appreciated. >>> >>> Thanks, >>> >>> G >>> >>> -- >>> 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. >>> >> >> -- >> 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. >> > > -- > 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 -- 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.
