diff --git a/chunkenc/cumdelta.go b/chunkenc/cumdelta.go
index 3df8889..4befc22 100644
--- a/chunkenc/cumdelta.go
+++ b/chunkenc/cumdelta.go
@@ -202,6 +202,20 @@ func (s *ReverseCumulativeDeltaCompressor) Unlock() {
 	s.state = nil
 }
 
+func (s *ReverseCumulativeDeltaCompressor) Renew() {
+	s.buf = conbuf.New(nil)
+	s.pos = 0
+	//
+	s.baseValue = 0
+	s.lastDelta = 0
+	s.lastDeltaSize = 0
+	s.h = 0
+}
+
+func (s *ReverseCumulativeDeltaCompressor) Chunks() [][]byte {
+	return s.buf.Chunks()
+}
+
 // DECOMPRESSOR
 
 type ReverseCumulativeDeltaDecompressor struct {
diff --git a/database/api.go b/database/api.go
index ca0991e..590d109 100644
--- a/database/api.go
+++ b/database/api.go
@@ -10,8 +10,6 @@ import (
 	"gordenko.dev/dima/qb/atree"
 	"gordenko.dev/dima/qb/bin"
 	"gordenko.dev/dima/qb/bufreader"
-	"gordenko.dev/dima/qb/chunkenc"
-	"gordenko.dev/dima/qb/conbuf"
 	"gordenko.dev/dima/qb/proto"
 	"gordenko.dev/dima/qb/transform"
 	"gordenko.dev/dima/qb/txlog"
@@ -426,6 +424,7 @@ type FilledPage struct {
 
 type tryAppendMeasuresResult struct {
 	ResultCode byte
+	Written    int
 	// MetricType    diploma.MetricType
 	// FracDigits    byte
 	// Since         uint32
@@ -452,150 +451,6 @@ func (s *Database) AppendMeasures(req proto.AppendMeasuresReq) uint16 {
 
 	switch result.ResultCode {
 	case CanAppend:
-		var (
-			rootPageNo    = result.RootPageNo
-			prevPageNo    = result.PrevPageNo
-			timestampsBuf = result.TimestampsBuf
-			valuesBuf     = result.ValuesBuf
-			timestamps    = result.Timestamps
-			values        = result.Values
-			since         = result.Since
-			until         = result.Until
-			untilValue    = result.UntilValue
-			//
-			//toAppendMeasures []proto.Measure
-
-			dataPages []atree.NotLinkedDataPage
-		)
-
-		for idx, measure := range req.Measures {
-			_ = idx
-			if since == 0 {
-				since = measure.Timestamp
-			} else {
-				if measure.Timestamp <= until {
-					// пишу в БД що вже встиг закодувати FIX
-					// if len(toAppendMeasures) > 0 {
-					// 	waitCh := s.txlog.WriteAppendMeasures(
-					// 		txlog.AppendedMeasures{
-					// 			MetricID: req.MetricID,
-					// 			Measures: toAppendMeasures,
-					// 		},
-					// 		false,
-					// 	)
-					// 	<-waitCh
-					// }
-					return proto.ErrExpiredMeasure
-				}
-
-				if result.MetricType == diploma.Cumulative && measure.Value < untilValue {
-					// пишу в БД що вже встиг закодувати FIX
-					// if len(toAppendMeasures) > 0 {
-					// 	waitCh := s.txlog.WriteAppendMeasures(
-					// 		txlog.AppendedMeasures{
-					// 			MetricID: req.MetricID,
-					// 			Measures: toAppendMeasures,
-					// 		},
-					// 		false,
-					// 	)
-					// 	<-waitCh
-					// }
-					return proto.ErrNonMonotonicValue
-				}
-			}
-
-			extraSpace := timestamps.CalcRequiredSpace(measure.Timestamp) +
-				values.CalcRequiredSpace(measure.Value)
-
-			totalSpace := timestamps.Size() + values.Size() + extraSpace
-
-			if totalSpace <= atree.DataPagePayloadSize {
-				// накопичую
-				timestamps.Append(measure.Timestamp)
-				values.Append(measure.Value)
-				//toAppendMeasures = append(toAppendMeasures, measure)
-			} else {
-				// сторінка заповнена
-				// if len(toAppendMeasures) > 0 {
-				// 	waitCh := s.txlog.WriteAppendMeasures(
-				// 		txlog.AppendedMeasures{
-				// 			MetricID: req.MetricID,
-				// 			Measures: toAppendMeasures,
-				// 		},
-				// 		true,
-				// 	)
-				// 	<-waitCh
-
-				// 	toAppendMeasures = nil
-				// }
-
-				pageData := make([]byte, atree.PageSize)
-
-				atree.ChunksToNotLinkedDataPage(pageData, atree.ChunksToNotLinkedDataPageReq{
-					//PrevPageNo:       path.LastPageNo,
-					TimestampsChunks: timestampsBuf.Chunks(),
-					TimestampsSize:   uint16(timestamps.Size()),
-					ValuesChunks:     valuesBuf.Chunks(),
-					ValuesSize:       uint16(values.Size()),
-				})
-
-				dataPages = append(dataPages, atree.NotLinkedDataPage{
-					Since: since,
-					Data:  pageData,
-				})
-
-				// FIX
-				// prevPageNo = report.DataPageNo
-				// if report.IsRootChanged {
-				// 	rootPageNo = report.NewRootPageNo
-				// }
-				// waitCh := s.txlog.WriteAppendedMeasureWithOverflow(
-				// 	txlog.AppendedMeasureWithOverflow{
-				// 		MetricID:         req.MetricID,
-				// 		Timestamp:        measure.Timestamp,
-				// 		Value:            measure.Value,
-				// 		IsDataPageReused: report.IsDataPageReused,
-				// 		DataPageNo:       report.DataPageNo,
-				// 		IsRootChanged:    report.IsRootChanged,
-				// 		RootPageNo:       report.NewRootPageNo,
-				// 		ReusedIndexPages: report.ReusedIndexPages,
-				// 	},
-				// 	(idx+1) < len(req.Measures),
-				// )
-				// <-waitCh
-
-				timestampsBuf = conbuf.New(nil)
-				valuesBuf = conbuf.New(nil)
-
-				timestamps = chunkenc.NewReverseTimeDeltaCompressor(
-					timestampsBuf, 0)
-				if result.MetricType == diploma.Cumulative {
-					values = chunkenc.NewReverseCumulativeDeltaCompressor(
-						valuesBuf, 0, result.FracDigits)
-				} else {
-					values = chunkenc.NewReverseInstantDeltaCompressor(
-						valuesBuf, 0, result.FracDigits)
-				}
-
-				timestamps.Append(measure.Timestamp)
-				values.Append(measure.Value)
-
-				since = measure.Timestamp
-			}
-
-			until = measure.Timestamp
-			untilValue = measure.Value
-		}
-
-		waitCh := s.txlog.Append(txlog.AppendedPagesReq{
-			MetricID:   req.MetricID,
-			Timestamp:  until,
-			Value:      untilValue,
-			LastPageNo: prevPageNo,
-			//Measures:   toAppendMeasures,
-		},
-		)
-		<-waitCh
 
 		// report, err := s.atree.AppendDataPage(atree.AppendDataPageReq{})
 		// if err != nil {
diff --git a/database/metric.go b/database/metric.go
index b40ad79..67c0019 100644
--- a/database/metric.go
+++ b/database/metric.go
@@ -1,25 +1,25 @@
 package database
 
 import (
-	octopus "gordenko.dev/dima/qb"
+	"gordenko.dev/dima/qb"
 	"gordenko.dev/dima/qb/conbuf"
 )
 
 // METRIC
 
 type _metric struct {
-	MetricType    octopus.MetricType
-	FracDigits    byte
-	RootPageNo    uint32
-	LastPageNo    uint32
-	SinceValue    float64
-	Since         uint32
-	UntilValue    float64
-	Until         uint32
-	TimestampsBuf *conbuf.ContinuousBuffer
-	ValuesBuf     *conbuf.ContinuousBuffer
-	Timestamps    octopus.TimestampCompressor
-	Values        octopus.ValueCompressor
+	MetricType qb.MetricType
+	FracDigits byte
+	RootPageNo uint32
+	LastPageNo uint32
+	SinceValue float64
+	Since      uint32
+	UntilValue float64
+	Until      uint32
+	//TimestampsBuf *conbuf.ContinuousBuffer
+	//ValuesBuf     *conbuf.ContinuousBuffer
+	Timestamps qb.TimestampCompressor
+	Values     qb.ValueCompressor
 }
 
 func (s *_metric) ReinitBy(timestamp uint32, value float64) {
diff --git a/database/proc.go b/database/proc.go
index ec758ce..3a58b52 100644
--- a/database/proc.go
+++ b/database/proc.go
@@ -3,7 +3,7 @@ package database
 import (
 	"fmt"
 
-	diploma "gordenko.dev/dima/qb"
+	qb "gordenko.dev/dima/qb"
 	"gordenko.dev/dima/qb/atree"
 	"gordenko.dev/dima/qb/chunkenc"
 	"gordenko.dev/dima/qb/conbuf"
@@ -51,19 +51,19 @@ func (s *Database) DoWork() {
 	for _, metricID := range rLocksToRelease {
 		lockEntry, ok := s.metricLockEntries[metricID]
 		if !ok {
-			diploma.Abort(diploma.NoLockEntryBug,
+			qb.Abort(qb.NoLockEntryBug,
 				fmt.Errorf("drainQueues: lockEntry not found for the metric %d",
 					metricID))
 		}
 
 		if lockEntry.XLock {
-			diploma.Abort(diploma.XLockBug,
+			qb.Abort(qb.XLockBug,
 				fmt.Errorf("drainQueues: xlock is set for the metric %d",
 					metricID))
 		}
 
 		if lockEntry.RLocks <= 0 {
-			diploma.Abort(diploma.NoRLockBug,
+			qb.Abort(qb.NoRLockBug,
 				fmt.Errorf("drainQueues: rlock not set for the metric %d",
 					metricID))
 		}
@@ -73,7 +73,7 @@ func (s *Database) DoWork() {
 		if len(lockEntry.WaitQueue) > 0 {
 			metric, ok := s.metrics[metricID]
 			if !ok {
-				diploma.Abort(diploma.NoMetricBug,
+				qb.Abort(qb.NoMetricBug,
 					fmt.Errorf("drainQueues: metric %d not found", metricID))
 			}
 			s.processMetricQueue(metricID, metric, lockEntry)
@@ -117,7 +117,7 @@ func (s *Database) DoWork() {
 			s.tryGetMetric(req)
 
 		default:
-			diploma.Abort(diploma.UnknownWorkerQueueItemBug,
+			qb.Abort(qb.UnknownWorkerQueueItemBug,
 				fmt.Errorf("bug: unknown worker queue item type %T", req))
 		}
 	}
@@ -169,7 +169,7 @@ func (s *Database) processMetricQueue(metricID uint32, metric *_metric, lockEntr
 				s.startDeleteMeasures(metric, req)
 
 			default:
-				diploma.Abort(diploma.UnknownMetricWaitQueueItemBug,
+				qb.Abort(qb.UnknownMetricWaitQueueItemBug,
 					fmt.Errorf("bug: unknown metric wait queue item type %T", req))
 			}
 
@@ -373,7 +373,7 @@ type ReadBound struct {
 // 		return
 // 	}
 
-// 	if metric.MetricType == diploma.Cumulative && req.Value < metric.UntilValue {
+// 	if metric.MetricType == qb.Cumulative && req.Value < metric.UntilValue {
 // 		req.ResultCh <- tryAppendMeasureResult{
 // 			MetricID:   req.MetricID,
 // 			ResultCode: NonMonotonicValue,
@@ -434,26 +434,26 @@ type ReadBound struct {
 // func (s *Database) appendMeasure(rec txlog.AppendedMeasure) {
 // 	metric, ok := s.metrics[rec.MetricID]
 // 	if !ok {
-// 		diploma.Abort(diploma.NoMetricBug,
+// 		qb.Abort(qb.NoMetricBug,
 // 			fmt.Errorf("appendMeasure: metric %d not found",
 // 				rec.MetricID))
 // 	}
 
 // 	lockEntry, ok := s.metricLockEntries[rec.MetricID]
 // 	if !ok {
-// 		diploma.Abort(diploma.NoLockEntryBug,
+// 		qb.Abort(qb.NoLockEntryBug,
 // 			fmt.Errorf("appendMeasure: lockEntry not found for the metric %d",
 // 				rec.MetricID))
 // 	}
 
 // 	if lockEntry.XLock {
-// 		diploma.Abort(diploma.XLockBug,
+// 		qb.Abort(qb.XLockBug,
 // 			fmt.Errorf("appendMeasure: xlock is set for the metric %d",
 // 				rec.MetricID))
 // 	}
 
 // 	if lockEntry.RLocks <= 0 {
-// 		diploma.Abort(diploma.NoRLockBug,
+// 		qb.Abort(qb.NoRLockBug,
 // 			fmt.Errorf("appendMeasure: rlock not set for the metric %d",
 // 				rec.MetricID))
 // 	}
@@ -481,58 +481,49 @@ type ReadBound struct {
 func (s *Database) appendMeasures(rec txlog.AppendedMeasures) {
 	metric, ok := s.metrics[rec.MetricID]
 	if !ok {
-		diploma.Abort(diploma.NoMetricBug,
+		qb.Abort(qb.NoMetricBug,
 			fmt.Errorf("appendMeasureAfterOverflow: metric %d not found",
 				rec.MetricID))
 	}
 
-	lockEntry, ok := s.metricLockEntries[rec.MetricID]
-	if !ok {
-		diploma.Abort(diploma.NoLockEntryBug,
-			fmt.Errorf("appendMeasureAfterOverflow: lockEntry not found for the metric %d",
-				rec.MetricID))
-	}
+	metric.Values.Unlock()
+	metric.Timestamps.Unlock()
 
-	if !lockEntry.XLock {
-		diploma.Abort(diploma.NoXLockBug,
-			fmt.Errorf("appendMeasureAfterOverflow: xlock not set for the metric %d",
-				rec.MetricID))
-	}
+	// lockEntry, ok := s.metricLockEntries[rec.MetricID]
+	// if !ok {
+	// 	qb.Abort(qb.NoLockEntryBug,
+	// 		fmt.Errorf("appendMeasureAfterOverflow: lockEntry not found for the metric %d",
+	// 			rec.MetricID))
+	// }
 
-	for _, measure := range rec.Measures {
-		if metric.Since == 0 {
-			metric.Since = measure.Timestamp
-			metric.SinceValue = measure.Value
-		}
+	// if !lockEntry.XLock {
+	// 	qb.Abort(qb.NoXLockBug,
+	// 		fmt.Errorf("appendMeasureAfterOverflow: xlock not set for the metric %d",
+	// 			rec.MetricID))
+	// }
 
-		metric.Timestamps.Append(measure.Timestamp)
-		metric.Values.Append(measure.Value)
-		metric.Until = measure.Timestamp
-		metric.UntilValue = measure.Value
-	}
-
-	lockEntry.XLock = false
-	s.doAfterReleaseXLock(rec.MetricID, metric, lockEntry)
+	// lockEntry.XLock = false
+	// s.doAfterReleaseXLock(rec.MetricID, metric, lockEntry)
 }
 
 // func (s *Database) appendMeasureAfterOverflow(extended txlog.AppendedMeasureWithOverflowExtended) {
 // 	rec := extended.Record
 // 	metric, ok := s.metrics[rec.MetricID]
 // 	if !ok {
-// 		diploma.Abort(diploma.NoMetricBug,
+// 		qb.Abort(qb.NoMetricBug,
 // 			fmt.Errorf("appendMeasureAfterOverflow: metric %d not found",
 // 				rec.MetricID))
 // 	}
 
 // 	lockEntry, ok := s.metricLockEntries[rec.MetricID]
 // 	if !ok {
-// 		diploma.Abort(diploma.NoLockEntryBug,
+// 		qb.Abort(qb.NoLockEntryBug,
 // 			fmt.Errorf("appendMeasureAfterOverflow: lockEntry not found for the metric %d",
 // 				rec.MetricID))
 // 	}
 
 // 	if !lockEntry.XLock {
-// 		diploma.Abort(diploma.NoXLockBug,
+// 		qb.Abort(qb.NoXLockBug,
 // 			fmt.Errorf("appendMeasureAfterOverflow: xlock not set for the metric %d",
 // 				rec.MetricID))
 // 	}
@@ -583,74 +574,170 @@ func (s *Database) tryAppendMeasures(req tryAppendMeasuresReq) {
 }
 
 func (s *Database) startAppendMeasures(metric *_metric, req tryAppendMeasuresReq, lockEntry *metricLockEntry) {
-	if lockEntry != nil {
-		if lockEntry.RLocks > 0 {
-			lockEntry.WaitQueue = append(lockEntry.WaitQueue, req)
-			return
-		}
-		lockEntry.XLock = true
-	} else {
-		s.metricLockEntries[req.MetricID] = &metricLockEntry{
-			XLock: true,
-		}
-	}
-
 	var (
-		timestampsBuf *conbuf.ContinuousBuffer
-		valuesBuf     *conbuf.ContinuousBuffer
-		timestamps    diploma.TimestampCompressor
-		values        diploma.ValueCompressor
+		timestamps = metric.Timestamps
+		values     = metric.Values
+
+		dataPages []atree.NotLinkedDataPage
+
+		resultCode byte
+		written    int
 	)
 
-	if metric.Since > 0 {
-		timestampsBuf = metric.TimestampsBuf.Copy()
-		valuesBuf = metric.ValuesBuf.Copy()
+	metric.Values.Lock()
+	metric.Timestamps.Lock()
 
-		timestamps = chunkenc.NewReverseTimeDeltaOfDeltaCompressor(
-			timestampsBuf, metric.Timestamps.Size())
-
-		if metric.MetricType == diploma.Cumulative {
-			values = chunkenc.NewReverseCumulativeDeltaCompressor(
-				valuesBuf, metric.Values.Size(), metric.FracDigits)
+	for idx, measure := range req.Measures {
+		if metric.Since == 0 {
+			metric.Since = measure.Timestamp
 		} else {
-			values = chunkenc.NewReverseInstantDeltaCompressor(
-				valuesBuf, metric.Values.Size(), metric.FracDigits)
+			// FIX - у випадку помилки треба в транзакції зберегти що помилка, але також зафіксувати скільки елементів збережено.
+			// якщо idx == 0 - одразу знімаю блокування і нічого не відправляю в txlog
+			if measure.Timestamp <= metric.Until {
+				if idx == 0 {
+					metric.Values.Unlock()
+					metric.Timestamps.Unlock()
+
+					req.ResultCh <- tryAppendMeasuresResult{
+						ResultCode: ExpiredMeasure,
+					}
+					return
+				}
+
+				resultCode = ExpiredMeasure
+				written = idx
+				break
+			}
+
+			if metric.MetricType == qb.Cumulative && measure.Value < metric.UntilValue {
+				if idx == 0 {
+					metric.Values.Unlock()
+					metric.Timestamps.Unlock()
+
+					req.ResultCh <- tryAppendMeasuresResult{
+						ResultCode: NonMonotonicValue,
+					}
+					return
+				}
+				resultCode = NonMonotonicValue
+				written = idx
+				break
+			}
 		}
+
+		// fix - 1 + 8 bytes
+		extraSpace := timestamps.CalcRequiredSpace(measure.Timestamp) +
+			values.CalcRequiredSpace(measure.Value)
+
+		totalSpace := timestamps.Size() + values.Size() + extraSpace
+
+		if totalSpace <= atree.DataPagePayloadSize {
+			// накопичую
+			timestamps.Append(measure.Timestamp)
+			values.Append(measure.Value)
+		} else {
+			// сторінка заповнена
+			pageData := make([]byte, atree.PageSize)
+
+			// prevPageNo - виставляю в txlog, коли забираю номер сторінки із freeList або генерую новий
+			atree.ChunksToNotLinkedDataPage(pageData, atree.ChunksToNotLinkedDataPageReq{
+				TimestampsChunks: timestamps.Chunks(),
+				TimestampsSize:   uint16(timestamps.Size()),
+				ValuesChunks:     values.Chunks(),
+				ValuesSize:       uint16(values.Size()),
+			})
+
+			dataPages = append(dataPages, atree.NotLinkedDataPage{
+				Since: metric.Since,
+				Data:  pageData,
+			})
+
+			// FIX
+			// prevPageNo = report.DataPageNo
+			// if report.IsRootChanged {
+			// 	rootPageNo = report.NewRootPageNo
+			// }
+			// waitCh := s.txlog.WriteAppendedMeasureWithOverflow(
+			// 	txlog.AppendedMeasureWithOverflow{
+			// 		MetricID:         req.MetricID,
+			// 		Timestamp:        measure.Timestamp,
+			// 		Value:            measure.Value,
+			// 		IsDataPageReused: report.IsDataPageReused,
+			// 		DataPageNo:       report.DataPageNo,
+			// 		IsRootChanged:    report.IsRootChanged,
+			// 		RootPageNo:       report.NewRootPageNo,
+			// 		ReusedIndexPages: report.ReusedIndexPages,
+			// 	},
+			// 	(idx+1) < len(req.Measures),
+			// )
+			// <-waitCh
+
+			timestamps.Renew()
+			values.Renew()
+
+			timestamps.Append(measure.Timestamp)
+			values.Append(measure.Value)
+
+			metric.Since = measure.Timestamp
+		}
+
+		metric.Until = measure.Timestamp
+		metric.UntilValue = measure.Value
+	}
+
+	// виділити змінені байти.
+	// скопіювати. Причому можна скопіювати зрізи chunks
+
+	if len(dataPages) > 0 {
+		// пишу в txlog довгим шляхом через redo файл і запис в data файл
 	} else {
-		timestampsBuf = conbuf.New(nil)
-		valuesBuf = conbuf.New(nil)
-		timestamps = chunkenc.NewReverseTimeDeltaOfDeltaCompressor(
-			timestampsBuf, 0)
-		if metric.MetricType == diploma.Cumulative {
-			values = chunkenc.NewReverseCumulativeDeltaCompressor(
-				valuesBuf, 0, metric.FracDigits)
-		} else {
-			values = chunkenc.NewReverseInstantDeltaCompressor(
-				valuesBuf, 0, metric.FracDigits)
-		}
+		// короткий шлях - запис лише в txlog
 	}
 
-	req.ResultCh <- tryAppendMeasuresResult{
-		ResultCode: CanAppend,
-		// MetricType:    metric.MetricType,
-		// FracDigits:    metric.FracDigits,
-		// Since:         metric.Since,
-		// Until:         metric.Until,
-		// UntilValue:    metric.UntilValue,
-		// RootPageNo:    metric.RootPageNo,
-		// PrevPageNo:    metric.LastPageNo,
-		// TimestampsBuf: timestampsBuf,
-		// ValuesBuf:     valuesBuf,
-		// Timestamps:    timestamps,
-		// Values:        values,
-	}
+	// waitCh := s.txlog.Append(txlog.AppendedPagesReq{
+	// 	MetricID:   req.MetricID,
+	// 	Timestamp:  until,
+	// 	Value:      untilValue,
+	// 	LastPageNo: prevPageNo,
+	// 	//Measures:   toAppendMeasures,
+	// },
+	// )
+	// <-waitCh
+
+	// if lockEntry != nil {
+	// 	if lockEntry.RLocks > 0 {
+	// 		lockEntry.WaitQueue = append(lockEntry.WaitQueue, req)
+	// 		return
+	// 	}
+	// 	lockEntry.XLock = true
+	// } else {
+	// 	s.metricLockEntries[req.MetricID] = &metricLockEntry{
+	// 		XLock: true,
+	// 	}
+	// }
+
+}
+
+type PartialChange struct {
+	Data   [][]byte
+	Size   int
+	Offset int
+}
+
+type AppendedMeasures struct {
+	RootPageNo uint32
+	LastPageNo uint32
+	DataPages  []atree.ChunksToNotLinkedDataPageReq
+	Values     PartialChange
+	Timestamps PartialChange
+	ResultCh   chan tryAppendMeasuresResult
 }
 
 type tryRangeScanReq struct {
 	MetricID       uint32
 	Since          uint32
 	Until          uint32
-	MetricType     diploma.MetricType
+	MetricType     qb.MetricType
 	ResponseWriter atree.WorkerMeasureConsumer
 	ResultCh       chan rangeScanResult
 }
@@ -739,7 +826,7 @@ func (*Database) startRangeScan(metric *_metric, req tryRangeScanReq) bool {
 
 		value, done := valueDecompressor.NextValue()
 		if done {
-			diploma.Abort(diploma.HasTimestampNoValueBug, ErrNoValueBug)
+			qb.Abort(qb.HasTimestampNoValueBug, ErrNoValueBug)
 		}
 
 		if timestamp <= req.Until {
@@ -770,7 +857,7 @@ func (*Database) startRangeScan(metric *_metric, req tryRangeScanReq) bool {
 
 type tryFullScanReq struct {
 	MetricID       uint32
-	MetricType     diploma.MetricType
+	MetricType     qb.MetricType
 	ResponseWriter atree.WorkerMeasureConsumer
 	ResultCh       chan fullScanResult
 }
@@ -834,7 +921,7 @@ func (*Database) startFullScan(metric *_metric, req tryFullScanReq) bool {
 		}
 		value, done := valueDecompressor.NextValue()
 		if done {
-			diploma.Abort(diploma.HasTimestampNoValueBug, ErrNoValueBug)
+			qb.Abort(qb.HasTimestampNoValueBug, ErrNoValueBug)
 		}
 		req.ResponseWriter.FeedNoSend(timestamp, value)
 	}
@@ -913,31 +1000,31 @@ func (s *Database) applyChanges(req txlog.Changes) {
 func (s *Database) addMetric(rec txlog.AddedMetric) {
 	_, ok := s.metrics[rec.MetricID]
 	if ok {
-		diploma.Abort(diploma.MetricAddedBug,
+		qb.Abort(qb.MetricAddedBug,
 			fmt.Errorf("addMetric: metric %d already added",
 				rec.MetricID))
 	}
 
 	lockEntry, ok := s.metricLockEntries[rec.MetricID]
 	if !ok {
-		diploma.Abort(diploma.NoLockEntryBug,
+		qb.Abort(qb.NoLockEntryBug,
 			fmt.Errorf("addMetric: lockEntry not found for the metric %d",
 				rec.MetricID))
 	}
 
 	if !lockEntry.XLock {
-		diploma.Abort(diploma.NoXLockBug,
+		qb.Abort(qb.NoXLockBug,
 			fmt.Errorf("addMetric: xlock not set for the metric %d",
 				rec.MetricID))
 	}
 
 	var (
-		values        diploma.ValueCompressor
+		values        qb.ValueCompressor
 		timestampsBuf = conbuf.New(nil)
 		valuesBuf     = conbuf.New(nil)
 	)
 
-	if rec.MetricType == diploma.Cumulative {
+	if rec.MetricType == qb.Cumulative {
 		values = chunkenc.NewReverseCumulativeDeltaCompressor(
 			valuesBuf, 0, byte(rec.FracDigits))
 	} else {
@@ -961,20 +1048,20 @@ func (s *Database) addMetric(rec txlog.AddedMetric) {
 func (s *Database) deleteMetric(rec txlog.DeletedMetric) {
 	_, ok := s.metrics[rec.MetricID]
 	if !ok {
-		diploma.Abort(diploma.NoMetricBug,
+		qb.Abort(qb.NoMetricBug,
 			fmt.Errorf("deleteMetric: metric %d not found",
 				rec.MetricID))
 	}
 
 	lockEntry, ok := s.metricLockEntries[rec.MetricID]
 	if !ok {
-		diploma.Abort(diploma.NoLockEntryBug,
+		qb.Abort(qb.NoLockEntryBug,
 			fmt.Errorf("deleteMetric: lockEntry not found for the metric %d",
 				rec.MetricID))
 	}
 
 	if !lockEntry.XLock {
-		diploma.Abort(diploma.NoXLockBug,
+		qb.Abort(qb.NoXLockBug,
 			fmt.Errorf("deleteMetric: xlock not set for the metric %d",
 				rec.MetricID))
 	}
@@ -1019,7 +1106,7 @@ func (s *Database) deleteMetric(rec txlog.DeletedMetric) {
 				}
 
 			default:
-				diploma.Abort(diploma.UnknownMetricWaitQueueItemBug,
+				qb.Abort(qb.UnknownMetricWaitQueueItemBug,
 					fmt.Errorf("bug: unknown metric wait queue item type %T", req))
 			}
 		}
@@ -1039,20 +1126,20 @@ func (s *Database) deleteMetric(rec txlog.DeletedMetric) {
 func (s *Database) deleteMeasures(rec txlog.DeletedMeasures) {
 	metric, ok := s.metrics[rec.MetricID]
 	if !ok {
-		diploma.Abort(diploma.NoMetricBug,
+		qb.Abort(qb.NoMetricBug,
 			fmt.Errorf("deleteMeasures: metric %d not found",
 				rec.MetricID))
 	}
 
 	lockEntry, ok := s.metricLockEntries[rec.MetricID]
 	if !ok {
-		diploma.Abort(diploma.NoLockEntryBug,
+		qb.Abort(qb.NoLockEntryBug,
 			fmt.Errorf("deleteMeasures: lockEntry not found for the metric %d",
 				rec.MetricID))
 	}
 
 	if !lockEntry.XLock {
-		diploma.Abort(diploma.NoXLockBug,
+		qb.Abort(qb.NoXLockBug,
 			fmt.Errorf("deleteMeasures: xlock not set for the metric %d",
 				rec.MetricID))
 	}
diff --git a/qb.go b/qb.go
index 1be7f8d..448a3df 100644
--- a/qb.go
+++ b/qb.go
@@ -26,7 +26,11 @@ type TimestampCompressor interface {
 	CalcRequiredSpace(uint32) int
 	Append(uint32)
 	Size() int
+	Chunks() [][]byte
 	DeleteLast()
+	Renew()
+	Lock()
+	Unlock()
 	//LastTimestamp() uint32
 }
 
@@ -34,7 +38,11 @@ type ValueCompressor interface {
 	CalcRequiredSpace(float64) int
 	Append(float64)
 	Size() int
+	Chunks() [][]byte
 	DeleteLast()
+	Renew() // створює новий conbuf, але не чіпає state
+	Lock()
+	Unlock()
 	//LastValue() float64
 }