I have an appengine app which has been running for about a year now, i
have mainly been using JDO queries until now, but i am trying to
collect stats and the queries are taking too long. I have the
following entity (Device)
public class Device implements Serializable{
...
@Persistent
private Set<Key> feeds;// Key for the Feed entity
...
}
So I want to get a count of how many Devices have a certain Feed. I
was doing it in JDOQL before as such (uses javax.jdo.Query):
Query query = pm.newQuery("select from Device where
feeds.contains(:feedKey)");
Map<String, Object> paramsf = new HashMap<String, Object>();
paramsf.put("feedKey",feed.getId());
List<Device> results = (List<Device>) query.executeWithMap(paramsf);
Though this code times out now. I was trying to use the Datastore API
so I could set chunk size,etc to see if i could speed the query up or
use a cursor, but I am unsure how to search in a Set field. I was
trying this (uses com.google.appengine.api.datastore.Query)
Query query = new Query("Device");
query.addFilter("feeds", FilterOperator.IN, feed.getId());
query.setKeysOnly();
final FetchOptions fetchOptions =
FetchOptions.Builder.withPrefetchSize(100).chunkSize(100);
QueryResultList<Entity> results =
dss.prepare(query).asQueryResultList(fetchOptions);
Essentially i am unsure how to search in the one-to-many filed (feeds)
for a single key. Is it possible to index it somehow?
hope it makes sense....
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