public async static Task PeriodicallyDisplayTopCountsState(string brokerList, RocksDb db, CancellationToken ct)
        {
            while (true)
            {
                await Task.Delay(10000, ct);
                var it = db.NewIterator(db.GetColumnFamily("counts")).SeekToFirst();

                var N = 5;
                var maxWords = new List<(int, string)>();
                while (it.Valid())
                {
                    var wc = (BitConverter.ToInt32(it.Value()), Encoding.UTF8.GetString(it.Key()));
                    if (maxWords.Count < N) { maxWords.Add(wc); }
                    else { if (wc.Item1 > maxWords[N-1].Item1) { maxWords[N-1] = wc; } }
                    maxWords.Sort((x, y) => y.Item1.CompareTo(x.Item1));
                    it.Next();
                }

                if (maxWords.Count > 0) { Console.WriteLine("Most frequently occuring words known to this instance:"); }
                foreach (var wc in maxWords)
                {
                    Console.WriteLine(" " + wc.Item2 + " " + wc.Item1);
                }
            }
        }
Beispiel #2
0
        public bool MoveNext()
        {
            if (_currentKey == null)
            {
                _currentKey = _start;
                // todo: check
                _iterator = _db.NewIterator();
                _iterator.Seek(_start);
                var firstKey = _iterator.Key();
                if (KeyConfig.ByteCompare(firstKey, _start) < 0)
                {
                    return(false);
                }
            }
            else
            {
                _nextFunction(_iterator);
                _currentKey = _iterator.Key();
            }

            if (!_iterator.Valid())
            {
                return(false);
            }

            var key = _iterator.Key();

            if (KeyConfig.ByteCompare(key, _end) > 0)
            {
                return(false);
            }
            return(true);
        }
Beispiel #3
0
        public static IEnumerable <(byte[] key, byte[] value)> Seek(this RocksDb db, ColumnFamilyHandle columnFamily, ReadOnlySpan <byte> prefix, SeekDirection direction, ReadOptions?readOptions)
        {
            var iterator = db.NewIterator(columnFamily, readOptions);

            if (direction == SeekDirection.Forward)
            {
                iterator.Seek(prefix);
                return(SeekInternal(iterator, iterator.Next));
            }
            else
            {
                iterator.SeekForPrev(prefix);
                return(SeekInternal(iterator, iterator.Prev));
            }

            IEnumerable <(byte[] key, byte[] value)> SeekInternal(Iterator iterator, Func <Iterator> nextAction)
            {
                using (iterator)
                {
                    while (iterator.Valid())
                    {
                        yield return(iterator.Key(), iterator.Value());

                        nextAction();
                    }
                }
            }
        }
Beispiel #4
0
        public static bool ColumnFamilyEmpty(this RocksDb db, ColumnFamilyHandle columnFamily, ReadOptions?readOptions = null)
        {
            var iter = db.NewIterator(columnFamily, readOptions);

            iter.SeekToFirst();
            return(!iter.Valid());
        }
Beispiel #5
0
        public IEnumerable <(byte[] Key, byte[] Value)> Seek(byte[] keyOrPrefix, SeekDirection direction)
        {
            if (keyOrPrefix == null)
            {
                keyOrPrefix = Array.Empty <byte>();
            }

            using var it = db.NewIterator(store.defaultFamily, options);

            byte[] fullKey = keyOrPrefix;

            if (direction == SeekDirection.Forward)
            {
                for (it.Seek(fullKey); it.Valid(); it.Next())
                {
                    yield return(it.Key(), it.Value());
                }
            }
            else
            {
                for (it.SeekForPrev(fullKey); it.Valid(); it.Prev())
                {
                    yield return(it.Key(), it.Value());
                }
            }
        }
Beispiel #6
0
        public async Task FlushCacheAsync(CancellationToken cancellationToken)
        {
            if (_bypassLocalCache)
            {
                throw new NotSupportedException();
            }

            var writeBatch  = new List <ContribSampleEntity>();
            var currentTime = DateTime.UtcNow;
            var cutoffTime  = new DateTime(currentTime.Year, currentTime.Month,
                                           currentTime.Day, currentTime.Hour, 0, 0, DateTimeKind.Utc);
            var zeroStream = new MemoryStream();

            _formatter.Serialize(zeroStream, 0);
            var zeroBuffer = zeroStream.GetBuffer();

            using (var i = _preAggDatabase.NewIterator())
            {
                while (i.Valid())
                {
                    var k = Encoding.UTF8.GetString(i.Key());
                    var v = (long)_formatter.Deserialize(new MemoryStream(i.Value()));
                    writeBatch.Add(new ContribSampleEntity(k, cutoffTime, v));
                    _preAggDatabase.Put(i.Key(), zeroBuffer);
                    i.Next();
                }
            }

            await IngestSamplesToXTableAsync(writeBatch, cancellationToken);
        }
Beispiel #7
0
        public uint GetCount()
        {
            uint count       = 0;
            var  readOptions = new ReadOptions();

            using (var iter = _db.NewIterator(readOptions: readOptions, cf: GetPartition()))
            {
                iter.SeekToFirst();
                while (iter.Valid())
                {
                    count++;
                    iter.Next();
                }
            }

            return(count);
        }
Beispiel #8
0
        public IEnumerable<(byte[] Key, byte[] Value)> Seek(byte table, byte[] keyOrPrefix, SeekDirection direction)
        {
            if (keyOrPrefix == null) keyOrPrefix = Array.Empty<byte>();

            using var it = db.NewIterator(store.GetFamily(table), options);

            if (direction == SeekDirection.Forward)
                for (it.Seek(keyOrPrefix); it.Valid(); it.Next())
                    yield return (it.Key(), it.Value());
Beispiel #9
0
        private static void RocksDb1()
        {
            string directory = @"C:\Users\Peska\source\repos\Esent.Tests\RocksDB";
            int    maxSize   = 1_000_000;

            TestObject[] objects = new TestObject[maxSize];

            for (int i = 0; i < maxSize; i++)
            {
                objects[i] = TestObject.Create();

                if (i % 1000 == 0)
                {
                    Console.WriteLine($"Created {i} records");
                }
            }

            DbOptions options = new DbOptions().SetCreateIfMissing();

            using (RocksDb rocksDb = RocksDbSharp.RocksDb.Open(options, directory))
            {
                for (int i = 0; i < maxSize; i++)
                {
                    string json = JsonConvert.SerializeObject(objects[i]);

                    rocksDb.Put(objects[i].EQNum, json);

                    if (i % 1000 == 0)
                    {
                        Console.WriteLine($"Indexed {i} records");
                    }
                }

                Random random = new Random();

                for (int i = 0; i < maxSize; i++)
                {
                    int randomInt = random.Next(maxSize - 1);

                    TestObject testObject = objects[randomInt];
                    TestObject fromDict   = JsonConvert.DeserializeObject <TestObject>(rocksDb.Get(testObject.EQNum));

                    if (testObject.EQNum != fromDict.EQNum)
                    {
                        throw new Exception("What the f**k");
                    }

                    if (i % 1000 == 0)
                    {
                        Console.WriteLine($"Retrieved {i} records");
                    }
                }

                Iterator iterator = rocksDb.NewIterator();
            }
        }
Beispiel #10
0
        private IEnumerable <Iterator> IterateDb(RocksDb db, byte[] prefix, Guid?chainId = null)
        {
            ColumnFamilyHandle cf = GetColumnFamily(db, chainId);

            using Iterator it = db.NewIterator(cf);
            for (it.Seek(prefix); it.Valid() && it.Key().StartsWith(prefix); it.Next())
            {
                yield return(it);
            }
        }
Beispiel #11
0
        public IEnumerable <(byte[] Key, byte[] Value)> Seek(byte table, byte[] keyOrPrefix, SeekDirection direction = SeekDirection.Forward)
        {
            if (keyOrPrefix == null)
            {
                keyOrPrefix = Array.Empty <byte>();
            }

            byte[] fullKey = getFullKey(table, keyOrPrefix);
            using var it = db.NewIterator(defaultFamily, Options.ReadDefault);
            if (direction == SeekDirection.Forward)
            {
                for (it.Seek(fullKey); it.Valid() && it.Key()[0] == table; it.Next())
                {
                    yield return(it.Key()[1..], it.Value());
Beispiel #12
0
        private T WithIterator <T>(Func <Iterator, T> body)
        {
            var ro       = RocksDbSnapshot();
            var iterator = database.NewIterator(cf: null, readOptions: ro);

            try
            {
                return(body(iterator));
            }
            finally
            {
                iterator.Dispose();
            }
        }
        public static IEnumerable <KeyValuePair <byte[], TValue> > Find <TValue>(this RocksDb db, byte[] keyPrefix, ColumnFamilyHandle?columnFamily = null, ReadOptions?readOptions = null)
            where TValue : ISerializable, new()
        {
            using (var iterator = db.NewIterator(columnFamily, readOptions))
            {
                iterator.Seek(keyPrefix);
                while (iterator.Valid())
                {
                    yield return(new KeyValuePair <byte[], TValue>(
                                     iterator.Key(), iterator.Value().AsSerializable <TValue>()));

                    iterator.Next();
                }
            }
        }
        public static Dictionary <byte[], byte[]> SelectDictionary(this RocksDb db, byte table)
        {
            var dict = new Dictionary <byte[], byte[]>();

            var enumerator = db.NewIterator();

            for (enumerator.SeekToFirst(); enumerator.Valid(); enumerator.Next())
            {
                if (enumerator.Key()[0] == table)
                {
                    dict.Add(enumerator.Key().AsSpan().Slice(1).ToArray(), enumerator.Value());
                }
            }

            return(dict);
        }
Beispiel #15
0
        private static void RocksDb2()
        {
            string directory = @"C:\Users\Peska\source\repos\Esent.Tests\RocksDB";

            DbOptions options = new DbOptions().SetCreateIfMissing();

            using (RocksDb rocksDb = RocksDbSharp.RocksDb.Open(options, directory))
            {
                TestObject o1 = new TestObject {
                    EQNum = "3L1234", Mnemonic = "20013L1234011"
                };
                TestObject o2 = new TestObject {
                    EQNum = "3L5678", Mnemonic = "20023L5678011"
                };
                TestObject o3 = new TestObject {
                    EQNum = "3L9012", Mnemonic = "20033L9012011"
                };
                TestObject o4 = new TestObject {
                    EQNum = "3L9012", Mnemonic = "20013L9012012"
                };

                rocksDb.Put(o1.Mnemonic, JsonConvert.SerializeObject(o1));
                rocksDb.Put(o2.Mnemonic, JsonConvert.SerializeObject(o2));
                rocksDb.Put(o3.Mnemonic, JsonConvert.SerializeObject(o3));
                rocksDb.Put(o4.Mnemonic, JsonConvert.SerializeObject(o4));

                SliceTransform         sliceTransform         = SliceTransform.CreateFixedPrefix(4);
                BlockBasedTableOptions blockBasedTableOptions = new BlockBasedTableOptions().SetWholeKeyFiltering(false);

                ColumnFamilyOptions columnFamilyOptions = new ColumnFamilyOptions()
                                                          .SetPrefixExtractor(sliceTransform)
                                                          .SetBlockBasedTableFactory(blockBasedTableOptions);

                ColumnFamilies columnFamilies = new ColumnFamilies(columnFamilyOptions);

                Iterator iterator = rocksDb.NewIterator();
                iterator = iterator.Seek("2001");

                while (iterator.Valid())
                {
                    string key   = iterator.StringKey();
                    string value = iterator.StringValue();

                    iterator.Next();
                }
            }
        }
Beispiel #16
0
        void ReadPackets(RocksDb db, short[] apidCounts)
        {
            var      readStopwatch = new Stopwatch();
            TimeSpan slowestRead   = new TimeSpan();
            var      slowestCount  = 0L;

            while (!isFinished)
            {
                for (var apid = 0; apid < apidCounts.Length; apid++)
                {
                    if (isFinished)
                    {
                        break;
                    }
                    if (apidCounts[apid] > 0)
                    {
                        readStopwatch.Reset();
                        readStopwatch.Start();
                        var firstKey = KeyToByteArray(new PacketKey {
                            APID = (short)apid, Timestamp = 0L
                        });
                        var lastKey = KeyToByteArray(new PacketKey {
                            APID = (short)apid, Timestamp = long.MaxValue
                        });

                        var count    = 0L;
                        var iterator = db.NewIterator();
                        for (iterator.Seek(firstKey); iterator.Valid(); iterator.Next())
                        {
                            if (!ByteArrayLessThanEqualTo(iterator.Key(), lastKey))
                            {
                                break;
                            }
                            count++;
                        }
                        readStopwatch.Stop();
                        if (readStopwatch.ElapsedTicks > slowestRead.Ticks)
                        {
                            slowestRead  = readStopwatch.Elapsed;
                            slowestCount = count;
                        }
                    }
                    System.Threading.Thread.Sleep(10);
                }
            }
            Console.WriteLine($"Read count={slowestCount}  slowest read={slowestRead}");
        }
Beispiel #17
0
        public IEnumerable <(byte[] Key, byte[] Value)> Seek(byte table, byte[] prefix, SeekDirection direction = SeekDirection.Forward)
        {
            using var it = db.NewIterator(GetFamily(table), Options.ReadDefault);
            for (it.Seek(prefix); it.Valid();)
            {
                yield return(it.Key(), it.Value());

                if (direction == SeekDirection.Forward)
                {
                    it.Next();
                }
                else
                {
                    it.Prev();
                }
            }
        }
Beispiel #18
0
        public IEnumerable <(byte[] Key, byte[] Value)> Seek(byte table, byte[] keyOrPrefix, SeekDirection direction)
        {
            using var it = db.NewIterator(store.GetFamily(table), options);
            for (it.Seek(keyOrPrefix); it.Valid();)
            {
                yield return(it.Key(), it.Value());

                if (direction == SeekDirection.Forward)
                {
                    it.Next();
                }
                else
                {
                    it.Prev();
                }
            }
        }
Beispiel #19
0
        public byte[][] GetAll()
        {
            var iterator = _db.NewIterator();

            iterator = iterator.SeekToFirst();
            var values = new List <byte[]>();

            while (iterator.Valid())
            {
                values.Add(iterator.Value());
                iterator = iterator.Next();
            }

            iterator.Dispose();

            return(values.ToArray());
        }
Beispiel #20
0
        private ICollection <byte[]> GetKeysOrValues(Func <Iterator, byte[]> selector)
        {
            ReadOptions   readOptions = new ReadOptions();
            List <byte[]> items       = new List <byte[]>();

            using (Iterator iter = _db.NewIterator(readOptions: readOptions))
            {
                iter.SeekToFirst();
                while (iter.Valid())
                {
                    byte[] item = selector.Invoke(iter);
                    items.Add(item);
                    iter.Next();
                }
            }

            return(items);
        }
Beispiel #21
0
 public IEnumerable <(byte[] Key, byte[] Value)> Find(byte table, byte[] prefix)
 {
     using var it = db.NewIterator(store.GetFamily(table), options);
     for (it.Seek(prefix); it.Valid(); it.Next())
     {
         var    key = it.Key();
         byte[] y   = prefix;
         if (key.Length < y.Length)
         {
             break;
         }
         if (!key.AsSpan().StartsWith(y))
         {
             break;
         }
         yield return(key, it.Value());
     }
 }
Beispiel #22
0
        IEnumerable <StoredValue> GetForPrefix(RocksDb db, ColumnFamilyHandle cf)
        {
            var readOptions = new ReadOptions();

            using (var iter = db.NewIterator(readOptions: readOptions, cf: cf))
            {
                GC.Collect();
                GC.WaitForPendingFinalizers();
                var b = Encoding.UTF8.GetBytes($"{_data.LocatorString}");
                iter.Seek(b);
                while (iter.Valid())
                {
                    Console.WriteLine(iter.StringKey());
                    yield return(iter.StringValue().Parse <StoredValue>());

                    iter.Next();
                }
            }
        }
        public RocksDbStore(string path)
        {
            var options = new DbOptions()
                .SetCreateIfMissing(true)
                .SetCreateMissingColumnFamilies(true);

            db = RocksDb.Open(options, path, ColumnFamilies);

            var writeBatch = new WriteBatch();
            var readOptions = new ReadOptions().SetFillCache(true);
            using (Iterator it = db.NewIterator(readOptions: readOptions))
            {
                for (it.SeekToFirst(); it.Valid(); it.Next())
                {
                    writeBatch.Delete(it.Key());
                }
            }
            db.Write(writeBatch);
        }
Beispiel #24
0
        private static void RocksDb4()
        {
            string directory = @"C:\Users\Peska\source\repos\Esent.Tests\RocksDB";

            DbOptions options = new DbOptions().SetCreateIfMissing(true);

            //SliceTransform sliceTransform = SliceTransform.CreateFixedPrefix(3);
            //ColumnFamilyOptions columnFamilyOptions = new ColumnFamilyOptions().SetPrefixExtractor(sliceTransform);
            //ColumnFamilies columnFamilies = new ColumnFamilies(columnFamilyOptions);

            using (RocksDb rocksDb = RocksDb.Open(options, directory))
            {
                rocksDb.Put("AABCE", "Test 3");
                rocksDb.Put("AAAAB", "Test 1");
                rocksDb.Put("AAABB", "Test 2");
                rocksDb.Put("AABCF", "Test 3");
                rocksDb.Put("AABBB", "Test 3");
                rocksDb.Put("ABBBB", "Test 4");
                rocksDb.Put("AABCC", "Test 3");
                rocksDb.Put("BBBBB", "Test 5");
                rocksDb.Put("AABCC", "Test 3");

                List <string> keys = new List <string>();

                using (Iterator iterator = rocksDb.NewIterator())
                {
                    iterator.Seek("AAB");

                    while (iterator.Valid())
                    {
                        keys.Add(iterator.StringKey());

                        iterator.Next();
                    }
                }

                Console.WriteLine(string.Join(", ", keys));
                Console.ReadLine();
            }
        }
Beispiel #25
0
        public IEnumerable <(byte[] Key, byte[] Value)> Seek(byte table, byte[] keyOrPrefix, SeekDirection direction = SeekDirection.Forward)
        {
            if (keyOrPrefix == null)
            {
                keyOrPrefix = Array.Empty <byte>();
            }

            using var it = db.NewIterator(GetFamily(table), Options.ReadDefault);
            if (direction == SeekDirection.Forward)
            {
                for (it.Seek(keyOrPrefix); it.Valid(); it.Next())
                {
                    yield return(it.Key(), it.Value());
                }
            }
            else
            {
                for (it.SeekForPrev(keyOrPrefix); it.Valid(); it.Prev())
                {
                    yield return(it.Key(), it.Value());
                }
            }
        }
Beispiel #26
0
        public void AddLogEntryByFollower(StateLogEntrySuggestion suggestion)
        {
            //remove all log bigger than this,(clear no committed logs)
            var key  = GetKey(suggestion.StateLogEntry.Term, suggestion.StateLogEntry.Index);
            var iter = db.NewIterator();

            iter.Seek(key);
            while (iter.Valid())
            {
                iter.Next();
                if (iter.Valid())
                {
                    db.Remove(iter.Key());
                }
                else
                {
                    break;
                }
            }
            //add this one
            AddLogEntry(suggestion);
            //update commit status
            if (suggestion.IsCommitted)
            {
                if (this.LastCommittedIndexTerm > suggestion.StateLogEntry.Term ||
                    (
                        this.LastCommittedIndexTerm == suggestion.StateLogEntry.Term &&
                        this.LastCommittedIndex > suggestion.StateLogEntry.Index
                    ))
                {
                    //Should be not possible
                }
                else
                {
                    this.LastCommittedIndex     = suggestion.StateLogEntry.Index;
                    this.LastCommittedIndexTerm = suggestion.StateLogEntry.Term;
                }
            }
        }
Beispiel #27
0
        public IActionResult Tally(List <IFormFile> files)
        {
            if (!HttpContext.Session.Keys.Contains(IsAuthenticated))
            {
                return(RedirectToAction("Signin"));
            }

            if (files.Count != 5)
            {
                return(RedirectToAction("Tally", new { msg = "Missing keys" }));
            }

            var kk = new List <string>();

            foreach (var f in files)
            {
                kk.Add((new StreamReader(f.OpenReadStream())).ReadToEnd());
            }

            if (!JoinKeys(kk))
            {
                return(RedirectToAction("Tally", new { msg = "Fail to obtain master key" }));
            }

            ElectionGuard.ElectionDescription eldesc;
            lock (_conf)
            {
                if (_conf.Get(ESElectionConfigurationKey) == null)
                {
                    throw new Exception("ESConfiguration missing");
                }
                eldesc = JsonSerializer.Deserialize <ElectionGuard.ElectionDescription>(_conf.Get(ESElectionConfigurationKey));
            }

            var protector = dataProtector.CreateProtector("SecureBallot");
            var ballots   = new List <BallotContent>();

            lock (secureBallot)
            {
                if (secureBallot.Get(VotingForTallyClosedKey) == null)
                {
                    secureBallot.Put(VotingForTallyClosedKey, DateTime.Now.ToString());
                }
                using (var it = secureBallot.NewIterator())
                {
                    it.SeekToFirst();
                    while (it.Valid())
                    {
                        // This is the only exception and it is the seal of the Ballot
                        if (it.StringKey() != HomeController.VotingForTallyClosedKey)
                        {
                            ballots.Add(BallotContent.FromJson(it.StringValue()));
                        }
                        it.Next();
                    }
                }
            }

            var clearBallots = ballots.ConvertAll(b => (b.ElectionId, protector.Unprotect(b.SecureVote)));

            var result = new Dictionary <string, Dictionary <string, int> >();

            foreach (var ballot in clearBallots.GroupBy(b => b.ElectionId))
            {
                var count = ballot.GroupBy(b => b.Item2);
                foreach (var c in count)
                {
                    if (!result.ContainsKey(ballot.Key))
                    {
                        result.Add(ballot.Key, new Dictionary <string, int>());
                    }

                    result[ballot.Key].Add(c.Key, c.Count());
                }
            }
            var elections = eldesc.contests.ToDictionary(g => g.object_id);

            return(View((result, elections)));
        }
Beispiel #28
0
            /// <inheritdoc />
            public GarbageCollectResult GarbageCollectByKeyValue(
                Func <Iterator, bool> canCollect,
                string columnFamilyName = null,
                IEnumerable <string> additionalColumnFamilies = null,
                CancellationToken cancellationToken           = default,
                byte[] startValue = null)
            {
                var gcStats = new GarbageCollectResult
                {
                    BatchSize = GarbageCollectionBatchSize
                };

                var columnFamilyInfo = GetColumnFamilyInfo(columnFamilyName);

                var columnFamilyHandleToUse = columnFamilyInfo.Handle;

                // According to RocksDB documentation, an iterator always loads both the key
                // and the value. To avoid this, when possible, we use the key-tracked column with just keys
                // and empty values and use that for eviction to avoid the load cost of full content.
                if (columnFamilyInfo.UseKeyTracking)
                {
                    columnFamilyHandleToUse = columnFamilyInfo.KeyHandle;
                }

                var keysToRemove  = new List <byte[]>();
                var primaryColumn = new string[] { columnFamilyName };
                var columnsToUse  = additionalColumnFamilies == null ?  primaryColumn : additionalColumnFamilies.Concat(primaryColumn);

                using (Iterator iterator = m_store.NewIterator(columnFamilyHandleToUse, m_readOptions))
                {
                    if (startValue != null)
                    {
                        iterator.Seek(startValue);
                    }
                    else
                    {
                        iterator.SeekToFirst();
                    }

                    bool reachedEnd = !iterator.Valid();
                    while (!reachedEnd && !cancellationToken.IsCancellationRequested)
                    {
                        gcStats.TotalCount++;
                        bool canCollectResult = canCollect(iterator);

                        if (canCollectResult)
                        {
                            var bytesKey = iterator.Key();
                            keysToRemove.Add(bytesKey);
                        }

                        iterator.Next();
                        reachedEnd = !iterator.Valid();

                        if (keysToRemove.Count == GarbageCollectionBatchSize ||
                            (reachedEnd && keysToRemove.Count > 0))
                        {
                            var startTime = TimestampUtilities.Timestamp;
                            // Remove the key across all specified columns
                            RemoveBatch(keysToRemove, columnFamilyNames: columnsToUse);

                            var duration = TimestampUtilities.Timestamp - startTime;

                            if (duration > gcStats.MaxBatchEvictionTime)
                            {
                                gcStats.MaxBatchEvictionTime = duration;
                            }

                            gcStats.LastKey       = keysToRemove.Last();
                            gcStats.RemovedCount += keysToRemove.Count;
                            keysToRemove.Clear();
                        }
                    }
                }

                gcStats.Canceled = cancellationToken.IsCancellationRequested;
                return(gcStats);
            }
Beispiel #29
0
 public IEnumerable <byte[]> GetAll()
 {
     using Iterator iterator = _rocksDb.NewIterator(_columnFamily);
     return(_mainDb.GetAllCore(iterator));
 }