smaller cleanup batches

src/main/java/com/commafeed/backend/dao/FeedEntryDAO.java

@@ -41,11 +41,14 @@ public class FeedEntryDAO extends GenericDAO<FeedEntry> {
 		return tuples.stream().map(t -> new FeedCapacity(t.get(entry.feed.id), t.get(count))).collect(Collectors.toList());
 	}
 
+	public int delete(Long feedId, long max) {
+		List<FeedEntry> list = newQuery().from(entry).where(entry.feed.id.eq(feedId)).limit(max).list(entry);
+		return delete(list);
+	}
+
 	public int deleteOldEntries(Long feedId, long max) {
 		List<FeedEntry> list = newQuery().from(entry).where(entry.feed.id.eq(feedId)).orderBy(entry.updated.asc()).limit(max).list(entry);
-		int deleted = list.size();
-		delete(list);
-		return deleted;
+		return delete(list);
 	}
 
 	@AllArgsConstructor

src/main/java/com/commafeed/backend/service/DatabaseCleaningService.java

@@ -17,6 +17,7 @@ import com.commafeed.backend.dao.FeedEntryDAO;
 import com.commafeed.backend.dao.FeedEntryDAO.FeedCapacity;
 import com.commafeed.backend.dao.FeedEntryStatusDAO;
 import com.commafeed.backend.dao.UnitOfWork;
+import com.commafeed.backend.model.Feed;
 
 /**
  * Contains utility methods for cleaning the database
@@ -40,7 +41,14 @@ public class DatabaseCleaningService {
 		long total = 0;
 		int deleted = 0;
 		do {
-			deleted = UnitOfWork.run(sessionFactory, () -> feedDAO.delete(feedDAO.findWithoutSubscriptions(1)));
+			List<Feed> feeds = UnitOfWork.run(sessionFactory, () -> feedDAO.findWithoutSubscriptions(1));
+			for (Feed feed : feeds) {
+				int entriesDeleted = 0;
+				do {
+					entriesDeleted = UnitOfWork.run(sessionFactory, () -> feedEntryDAO.delete(feed.getId(), BATCH_SIZE));
+				} while (entriesDeleted == BATCH_SIZE);
+			}
+			deleted = UnitOfWork.run(sessionFactory, () -> feedDAO.delete(feeds));
 			total += deleted;
 			log.info("removed {} feeds without subscriptions", total);
 		} while (deleted != 0);