+1 especially for large tables
On Jan 22, 10:47 am, Locke <locke2...@gmail.com> wrote:
> It would be good to have the ability to do this from within the GUI.
> Other database management tools have "empty table" options, so a
> "delete all of this Kind" feature would be appropriate.
>
> On Jan 22, 12:59 pm, John Patterson <jdpatter...@gmail.com> wrote:
>
>
>
> > Here is the code I use to delete one kind at a time - it batches the
> > keys into Lists of 100 to avoid datastore exceptions. Iterables is
> > from Google collections.
>
> > Query query = new Query(kind);
> > query.setKeysOnly();
> > DatastoreService datastore = ...
> > Iterable<Entity> entityIterator =
> > datastore.prepare(query).asIterable();
> > Iterable<Key> keyIterator =
> > Iterables.transform(entityIterator,
> > new Function<Entity, Key>()
> > {
> > public Key apply(Entity
> > arg0)
> > {
> > return
> > arg0.getKey();
> > }
> > });
>
> > Iterable<List<Key>> partitioned =
> > Iterables.partition(keyIterator, 100);
> > for (List<Key> sublist :
> > partitioned)
> > {
> > datastore.delete(sublist);
> > }
>
> > On 22 Jan 2010, at 15:10, mete wrote:
>
> > > Suppose I have a class A and I have stored some instance of it in the
> > > datastore. Then I change it, but I keep the name. How I can delete all
> > > the previous data in the datastore, if I simply do a query and use
> > > deleteAll, it gives an error (I guess because I changed the name of
> > > some fields). Thank you.
>
> > > Mete
>
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