Examples of com.mongodb.DBCursor

com.mongodb.DBCursor
An iterator over database results. Doing a find() query on a collection returns a DBCursor thus
```
 DBCursor cursor = collection.find( query ); if( cursor.hasNext() ) DBObject obj = cursor.next(); 
```
Warning: Calling toArray or length on a DBCursor will irrevocably turn it into an array. This means that, if the cursor was iterating over ten million results (which it was lazily fetching from the database), suddenly there will be a ten-million element array in memory. Before converting to an array, make sure that there are a reasonable number of results using skip() and limit().
For example, to get an array of the 1000-1100th elements of a cursor, use
```
 List obj = collection.find( query ).skip( 1000 ).limit( 100 ).toArray(); 
```
@dochub cursors

        //_deletedOnce == true && _modified < lastModifiedTime
        DBObject query =
                start(NodeDocument.DELETED_ONCE).is(Boolean.TRUE)
                                .put(NodeDocument.MODIFIED_IN_SECS).lessThan(Commit.getModifiedInSecs(lastModifiedTime))
                        .get();
        DBCursor cursor = getNodeCollection().find(query).setReadPreference(ReadPreference.secondaryPreferred());
        return CloseableIterable.wrap(transform(cursor, new Function<DBObject, NodeDocument>() {
            @Override
            public NodeDocument apply(DBObject input) {
                return store.convertFromDBObject(Collection.NODES, input);
            }

View Full Code Here


    private void logSplitDocIdsTobeDeleted(DBObject query) {
        // Fetch only the id
        final BasicDBObject keys = new BasicDBObject(Document.ID, 1);
        List<String> ids;
        DBCursor cursor = getNodeCollection().find(query, keys)
                .setReadPreference(ReadPreference.secondaryPreferred());
        try {
             ids = ImmutableList.copyOf(Iterables.transform(cursor, new Function<DBObject, String>() {
                 @Override
                 public String apply(@Nullable DBObject input) {
                     return (String) input.get(Document.ID);
                 }
             }));
        } finally {
            cursor.close();
        }
        StringBuilder sb = new StringBuilder("Split documents with following ids were deleted as part of GC \n");
        Joiner.on(StandardSystemProperty.LINE_SEPARATOR.value()).appendTo(sb, ids);
        log.debug(sb.toString());
    }

View Full Code Here

                        .put(NodeDocument.MODIFIED_IN_SECS).greaterThanEquals(
                                Commit.getModifiedInSecs(startTime))
                        .get();
        DBObject sortFields = new BasicDBObject(NodeDocument.MODIFIED_IN_SECS, -1);


        DBCursor cursor =
                getNodeCollection().find(query)
                        .sort(sortFields)
                        .setReadPreference(
                                ReadPreference.secondaryPreferred());
        return CloseableIterable.wrap(transform(cursor, new Function<DBObject, NodeDocument>() {

View Full Code Here

            // Fetch only the lastRev map and id
            final BasicDBObject keys = new BasicDBObject(Document.ID, 1);
            keys.put(Document.MOD_COUNT, 1);


            // Fetch lastRev for each such node
            DBCursor cursor = nodes.find(query.get(), keys);
            result.queryCount++;


            for (DBObject obj : cursor) {
                result.cacheEntriesProcessedCount++;
                String id = (String) obj.get(Document.ID);

View Full Code Here


                        QueryBuilder query = QueryBuilder.start(Document.ID)
                                .in(idBatch);


                        // Fetch lastRev and modCount for each such nodes
                        DBCursor cursor = nodes.find(query.get(), keys);
                        LOG.debug(
                                "Checking for changed nodes at level {} with {} paths",
                                tn.level(), sameLevelNodes.size());
                        result.queryCount++;
                        try {
                            for (DBObject obj : cursor) {


                                result.cacheEntriesProcessedCount++;


                                Number latestModCount = (Number) obj.get(Document.MOD_COUNT);
                                String id = (String) obj.get(Document.ID);


                                final TreeNode tn2 = sameLevelNodes.get(id);
                                CachedNodeDocument cachedDoc = tn2.getDocument();
                                if (cachedDoc != null) {
                                    boolean noChangeInModCount = Objects.equal(latestModCount, cachedDoc.getModCount());
                                    if (noChangeInModCount) {
                                        result.upToDateCount++;
                                        tn2.markUptodate(startTime);
                                    } else {
                                        result.invalidationCount++;
                                        tn2.invalidate();
                                    }
                                }


                                // Remove the processed nodes
                                sameLevelNodes.remove(tn2.getId());
                            }
                        } finally {
                            cursor.close();
                        }
                    }


                    // NodeDocument present in cache but not in database
                    // Remove such nodes from cache

View Full Code Here

  public void testCollectionViaCursor() throws UnknownHostException, MongoException {
    MongoDao dao = MongoDao.Factory.newTestMongoDao();
    
    DBCollection col = dao.getDbCollection();
    
    DBCursor cur = col.find();


        while(cur.hasNext()) {
            System.out.println(cur.next());
        }
  }

View Full Code Here

  }


  @Override
  public Collection<PropertyRecord> find(String propertyName,
      String propertyValue) {
    DBCursor dbCursor = this.dbCollection.find(new BasicDBObject(
        propertyName, propertyValue));
    if (dbCursor == null)
      return null;
    return new PropertyRecordList(dbCursor);
  }

View Full Code Here

      if (property.getValue() instanceof String) {
        queryParts.add(queryPart);
      }
    }
    logger.debug("query: " + query);
    DBCursor dbCursor = this.dbCollection.find(query);
    if (dbCursor == null)
      return null;
    return new PropertyRecordList(dbCursor);
  }

View Full Code Here

  @Override
  public void refresh(Collection<Refreshable> alreadyRefreshed) {
    Date ts = new Date(0);
    BasicDBObject query = new BasicDBObject();
    query.put("deleted_at", new BasicDBObject("$gt", mongoTimestamp));
    DBCursor cursor = collection.find(query);
    while (cursor.hasNext()) {
      Map<String,Object> user = (Map<String,Object>) cursor.next().toMap();
      String userID = getID(user.get(mongoUserID), true);
      Collection<List<String>> items = Lists.newArrayList();
      List<String> item = Lists.newArrayList();
      item.add(getID(user.get(mongoItemID), false));
      item.add(Float.toString(getPreference(user.get(mongoPreference))));
      items.add(item);
      try {
        refreshData(userID, items, false);
      } catch (NoSuchUserException e) {
        log.warn("No such user ID: {}", userID);
      } catch (NoSuchItemException e) {
        log.warn("No such items: {}", items);
      }
      if (ts.compareTo(getDate(user.get("created_at"))) < 0) {
        ts = getDate(user.get("created_at"));
      }
    }
    query = new BasicDBObject();
    query.put("created_at", new BasicDBObject("$gt", mongoTimestamp));
    cursor = collection.find(query);
    while (cursor.hasNext()) {
      Map<String,Object> user = (Map<String,Object>) cursor.next().toMap();
      if (!user.containsKey("deleted_at")) {
        String userID = getID(user.get(mongoUserID), true);
        Collection<List<String>> items = Lists.newArrayList();
        List<String> item = Lists.newArrayList();
        item.add(getID(user.get(mongoItemID), false));

View Full Code Here

      collectionMap.ensureIndex(indexObj);
      indexObj = new BasicDBObject();
      indexObj.put("long_value", 1);
      collectionMap.ensureIndex(indexObj);
      collectionMap.remove(new BasicDBObject());
      DBCursor cursor = collection.find();
      while (cursor.hasNext()) {
        Map<String,Object> user = (Map<String,Object>) cursor.next().toMap();
        if (!user.containsKey("deleted_at")) {
          long userID = Long.parseLong(fromIdToLong(getID(user.get(mongoUserID), true), true));
          long itemID = Long.parseLong(fromIdToLong(getID(user.get(mongoItemID), false), false));
          float ratingValue = getPreference(user.get(mongoPreference));
          Collection<Preference> userPrefs = userIDPrefMap.get(userID);

View Full Code Here

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