diff --git a/client/client.go b/client/client.go
index 98b477d..8b695da 100644
--- a/client/client.go
+++ b/client/client.go
@@ -54,6 +54,7 @@ func (s *Connection) mustSuccess(reader *bufreader.BufferedReader) (err error) {
 	}
 	switch code {
 	case proto.RespSuccess:
+		fmt.Println("SUCCESS")
 		return nil // ok
 	case proto.RespError:
 		return s.onError()
@@ -70,6 +71,7 @@ func (s *Connection) AddMetric(req proto.AddMetricReq) (err error) {
 		req.FracDigits,
 	}
 	bin.PutUint32(arr[1:], req.MetricID)
+	fmt.Println("arr", arr)
 	// req
 	if _, err = s.conn.Write(arr); err != nil {
 		return
diff --git a/database/api.go b/database/api.go
index c36aa6b..fcb01d7 100644
--- a/database/api.go
+++ b/database/api.go
@@ -45,6 +45,8 @@ func reply(conn io.Writer, errcode uint16) {
 func (s *Database) handleTCPConn(conn net.Conn) {
 	defer conn.Close()
 
+	fmt.Println("client connected")
+
 	r := bufreader.New(conn, 128)
 
 	for {
@@ -59,6 +61,7 @@ func (s *Database) handleTCPConn(conn net.Conn) {
 }
 
 func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (err error) {
+	fmt.Println("process request")
 	messageType, err := r.ReadByte()
 	if err != nil {
 		if err != io.EOF {
@@ -68,6 +71,8 @@ func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (e
 		}
 	}
 
+	fmt.Println("messageType:", messageType)
+
 	switch messageType {
 	case proto.TypeGetMetric:
 		req, err := proto.ReadGetMetricReq(r)
@@ -83,6 +88,7 @@ func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (e
 		if err != nil {
 			return fmt.Errorf("proto.ReadAddMetricReq: %s", err)
 		}
+		fmt.Println("ReadAddMetricReq:", req)
 		reply(conn, s.AddMetric(req))
 
 	case proto.TypeDeleteMetric:
@@ -154,6 +160,7 @@ func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (e
 		}
 
 	case proto.TypeDeleteMeasures:
+		//fmt.Println("delete metric")
 		req, err := proto.ReadDeleteMeasuresReq(r)
 		if err != nil {
 			return fmt.Errorf("proto.ReadDeleteMeasuresReq: %s", err)
@@ -180,6 +187,7 @@ func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (e
 		}
 
 	default:
+		fmt.Printf("unknown messageType: %d\n", messageType)
 		return fmt.Errorf("unknown messageType: %d", messageType)
 	}
 	return
@@ -188,6 +196,7 @@ func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (e
 // API
 
 func (s *Database) AddMetric(req proto.AddMetricReq) uint16 {
+	fmt.Println("database.AddMetric")
 	// Валидация
 	if req.MetricID == 0 {
 		return proto.ErrEmptyMetricID
@@ -204,26 +213,33 @@ func (s *Database) AddMetric(req proto.AddMetricReq) uint16 {
 
 	resultCh := make(chan byte, 1)
 
-	s.appendJobToWorkerQueue(tryAddMetricReq{
+	fmt.Println("add job")
+
+	s.worker.AddJobToQueue(tryAddMetricReq{
 		MetricID: req.MetricID,
 		ResultCh: resultCh,
 	})
 
+	fmt.Println("job added")
+
 	resultCode := <-resultCh
 
 	switch resultCode {
 	case Succeed:
-		s.storage.Append(storage.MetricAddRecord{
-			MetricID:   req.MetricID,
-			MetricType: req.MetricType,
-			FracDigits: req.FracDigits,
-		})
+		fmt.Println("OK")
+		// s.storage.Append(storage.MetricAddRecord{
+		// 	MetricID:   req.MetricID,
+		// 	MetricType: req.MetricType,
+		// 	FracDigits: req.FracDigits,
+		// })
 		//<-waitCh
 
 	case MetricDuplicate:
+		fmt.Println("ErrDuplicate")
 		return proto.ErrDuplicate
 
 	default:
+		fmt.Println("ErrWrongResultCodeBug")
 		qb.Abort(qb.WrongResultCodeBug, ErrWrongResultCodeBug)
 	}
 	return 0
@@ -238,7 +254,7 @@ type Metric struct {
 func (s *Database) GetMetric(conn io.Writer, req proto.GetMetricReq) error {
 	resultCh := make(chan Metric, 1)
 
-	s.appendJobToWorkerQueue(tryGetMetricReq{
+	s.worker.AddJobToQueue(tryGetMetricReq{
 		MetricID: req.MetricID,
 		ResultCh: resultCh,
 	})
@@ -277,7 +293,7 @@ type tryDeleteMetricResult struct {
 func (s *Database) DeleteMetric(req proto.DeleteMetricReq) uint16 {
 	resultCh := make(chan tryDeleteMetricResult, 1)
 
-	s.appendJobToWorkerQueue(tryDeleteMetricReq{
+	s.worker.AddJobToQueue(tryDeleteMetricReq{
 		MetricID: req.MetricID,
 		ResultCh: resultCh,
 	})
@@ -441,7 +457,7 @@ type tryAppendMeasuresResult struct {
 func (s *Database) AppendMeasures(req proto.AppendMeasuresReq) uint16 {
 	resultCh := make(chan tryAppendMeasuresResult, 1)
 
-	s.appendJobToWorkerQueue(tryAppendMeasuresReq{
+	s.worker.AddJobToQueue(tryAppendMeasuresReq{
 		MetricID: req.MetricID,
 		Measures: req.Measures,
 		ResultCh: resultCh,
@@ -486,7 +502,7 @@ type tryDeleteMeasuresResult struct {
 func (s *Database) DeleteMeasures(req proto.DeleteMeasuresReq) uint16 {
 	resultCh := make(chan tryDeleteMeasuresResult, 1)
 
-	s.appendJobToWorkerQueue(tryDeleteMeasuresReq{
+	s.worker.AddJobToQueue(tryDeleteMeasuresReq{
 		MetricID: req.MetricID,
 		Since:    req.Since,
 		ResultCh: resultCh,
@@ -667,7 +683,7 @@ type rangeScanReq struct {
 func (s *Database) rangeScan(req rangeScanReq) error {
 	resultCh := make(chan rangeScanResult, 1)
 
-	s.appendJobToWorkerQueue(tryRangeScanReq{
+	s.worker.AddJobToQueue(tryRangeScanReq{
 		MetricID:       req.MetricID,
 		Since:          req.Since,
 		Until:          req.Until,
@@ -689,7 +705,7 @@ func (s *Database) rangeScan(req rangeScanReq) error {
 			LastPageNo:     result.LastPageNo,
 			Since:          req.Since,
 		})
-		s.metricRUnlock(req.MetricID)
+		//s.metricRUnlock(req.MetricID)
 
 		if err != nil {
 			reply(req.Conn, proto.ErrUnexpected)
@@ -705,7 +721,7 @@ func (s *Database) rangeScan(req rangeScanReq) error {
 			Since:          req.Since,
 			Until:          req.Until,
 		})
-		s.metricRUnlock(req.MetricID)
+		//s.metricRUnlock(req.MetricID)
 
 		if err != nil {
 			reply(req.Conn, proto.ErrUnexpected)
@@ -735,7 +751,7 @@ type fullScanReq struct {
 func (s *Database) fullScan(req fullScanReq) error {
 	resultCh := make(chan fullScanResult, 1)
 
-	s.appendJobToWorkerQueue(tryFullScanReq{
+	s.worker.AddJobToQueue(tryFullScanReq{
 		MetricID:       req.MetricID,
 		MetricType:     req.MetricType,
 		ResponseWriter: req.ResponseWriter,
@@ -754,7 +770,7 @@ func (s *Database) fullScan(req fullScanReq) error {
 			ResponseWriter: req.ResponseWriter,
 			LastPageNo:     result.LastPageNo,
 		})
-		s.metricRUnlock(req.MetricID)
+		s.worker.AddJobToQueue(req.MetricID)
 		if err != nil {
 			reply(req.Conn, proto.ErrUnexpected)
 		} else {
@@ -779,7 +795,7 @@ func (s *Database) ListCurrentValues(conn net.Conn, req proto.ListCurrentValuesR
 
 	resultCh := make(chan struct{})
 
-	s.appendJobToWorkerQueue(tryListCurrentValuesReq{
+	s.worker.AddJobToQueue(tryListCurrentValuesReq{
 		MetricIDs:      req.MetricIDs,
 		ResponseWriter: responseWriter,
 		ResultCh:       resultCh,
diff --git a/database/database.go b/database/database.go
index db8d10b..382e149 100644
--- a/database/database.go
+++ b/database/database.go
@@ -10,8 +10,8 @@ import (
 	"sync"
 	"time"
 
+	"gordenko.dev/dima/qb"
 	"gordenko.dev/dima/qb/atree"
-	"gordenko.dev/dima/qb/freelist"
 	"gordenko.dev/dima/qb/storage"
 )
 
@@ -30,24 +30,20 @@ func JoinWALFileName(dir string, snapshotNumber int) string {
 // }
 
 type Database struct {
-	mutex           sync.Mutex
-	workerSignalCh  chan struct{}
-	workerQueue     []any
-	rLocksToRelease []uint32
-	metrics         map[uint32]*_metric
+	mutex  sync.Mutex
+	worker *Worker
 	//metricLockEntries map[uint32]*metricLockEntry
-	dataFreeList   *freelist.FreeList
-	indexFreeList  *freelist.FreeList
-	dir            string
-	databaseName   string
-	snapshotNumber int
-	storage        *storage.Writer
-	atree          *atree.Atree
-	tcpPort        int
-	logfile        *os.File
-	logger         *log.Logger
-	exitCh         chan struct{}
-	waitGroup      *sync.WaitGroup
+	//dataFreeList  *freelist.FreeList
+	//indexFreeList *freelist.FreeList
+	dir          string
+	databaseName string
+	storage      *storage.Writer
+	atree        *atree.Atree
+	tcpPort      int
+	logfile      *os.File
+	logger       *log.Logger
+	exitCh       chan struct{}
+	waitGroup    *sync.WaitGroup
 }
 
 type Options struct {
@@ -92,31 +88,41 @@ func New(opt Options) (_ *Database, err error) {
 	// 	return nil, err
 	// }
 
-	dataFreeList, err := freelist.New(freelist.Options{
-		PageSize:      2048,
-		BaseFilePath:  filepath.Join(opt.Dir, opt.DatabaseName+".free_data_base"),
-		DeltaFilePath: filepath.Join(opt.Dir, opt.DatabaseName+".free_data_delta"),
-	})
+	// dataFreeList, err := freelist.New(freelist.Options{
+	// 	PageSize:      2048,
+	// 	BaseFilePath:  filepath.Join(opt.Dir, opt.DatabaseName+".free_data"),
+	// 	DeltaFilePath: filepath.Join(opt.Dir, opt.DatabaseName+".free_data_delta"),
+	// })
 
-	indexFreeList, err := freelist.New(freelist.Options{
-		PageSize:      2048,
-		BaseFilePath:  filepath.Join(opt.Dir, opt.DatabaseName+".free_index_base"),
-		DeltaFilePath: filepath.Join(opt.Dir, opt.DatabaseName+".free_index_delta"),
+	// indexFreeList, err := freelist.New(freelist.Options{
+	// 	PageSize:      2048,
+	// 	BaseFilePath:  filepath.Join(opt.Dir, opt.DatabaseName+".free_index"),
+	// 	DeltaFilePath: filepath.Join(opt.Dir, opt.DatabaseName+".free_index_delta"),
+	// })
+
+	worker := NewWorker(WorkerOptions{
+		//
+		Metrics: make(map[uint32]*_metric),
+		Dir:     opt.Dir,
+		SaveToStorage: func(in any) {
+			fmt.Println("save to storage")
+		},
+		ExitCh:    opt.ExitCh,
+		WaitGroup: opt.WaitGroup,
 	})
 
 	s := &Database{
-		workerSignalCh: make(chan struct{}, 1),
-		dir:            opt.Dir,
-		databaseName:   opt.DatabaseName,
-		metrics:        make(map[uint32]*_metric),
+		worker:       worker,
+		dir:          opt.Dir,
+		databaseName: opt.DatabaseName,
 		//metricLockEntries: make(map[uint32]*metricLockEntry),
-		dataFreeList:  dataFreeList,
-		indexFreeList: indexFreeList,
-		tcpPort:       opt.TCPPort,
-		logfile:       opt.Logfile,
-		logger:        log.New(opt.Logfile, "", log.LstdFlags),
-		exitCh:        opt.ExitCh,
-		waitGroup:     opt.WaitGroup,
+		//dataFreeList:  dataFreeList,
+		//indexFreeList: indexFreeList,
+		tcpPort:   opt.TCPPort,
+		logfile:   opt.Logfile,
+		logger:    log.New(opt.Logfile, "", log.LstdFlags),
+		exitCh:    opt.ExitCh,
+		waitGroup: opt.WaitGroup,
 	}
 	return s, nil
 }
@@ -127,18 +133,32 @@ func (s *Database) ListenAndServe() (err error) {
 		return fmt.Errorf("net.Listen: %s; port=%d", err, s.tcpPort)
 	}
 
-	s.atree, err = atree.New(atree.Options{
-		Dir:          s.dir,
-		DatabaseName: s.databaseName,
+	s.storage, err = storage.NewWriter(storage.WriterOptions{
+		Dir: s.dir,
+		//LogNumber:           logNumber,
+		AppendToWorkerQueue: s.worker.AddJobToQueue,
+		//FreeList:            s.freeList,
+		//Atree:               s.atree,
+		ExitCh:    s.exitCh,
+		WaitGroup: s.waitGroup,
 	})
 	if err != nil {
-		return fmt.Errorf("atree.New: %s", err)
+		qb.Abort(qb.CreateChangesWriterFailed, err)
+
 	}
-	s.atree.Run()
+	go s.storage.Run()
 
-	go s.worker()
+	// s.atree, err = atree.New(atree.Options{
+	// 	Dir:          s.dir,
+	// 	DatabaseName: s.databaseName,
+	// })
+	// if err != nil {
+	// 	return fmt.Errorf("atree.New: %s", err)
+	// }
+	// s.atree.Run()
 
-	s.recovery()
+	s.waitGroup.Add(1)
+	go s.worker.Run()
 
 	s.logger.Println("database started")
 	for {
@@ -153,92 +173,6 @@ func (s *Database) ListenAndServe() (err error) {
 	}
 }
 
-func (s *Database) recovery() {
-	// FIX
-	// advisor, err := recovery.NewRecoveryAdvisor(recovery.RecoveryAdvisorOptions{
-	// 	Dir:            s.dir,
-	// 	VerifySnapshot: s.verifySnapshot,
-	// })
-	// if err != nil {
-	// 	panic(err)
-	// }
-
-	// recipe, err := advisor.GetRecipe()
-	// if err != nil {
-	// 	qb.Abort(qb.GetRecoveryRecipeFailed, err)
-	// }
-
-	// var logNumber int
-
-	// if recipe != nil {
-	// 	if recipe.Snapshot != "" {
-	// 		err = s.loadSnapshot(recipe.Snapshot)
-	// 		if err != nil {
-	// 			qb.Abort(qb.LoadSnapshotFailed, err)
-	// 		}
-	// 	}
-	// 	for _, changesFileName := range recipe.Changes {
-	// 		err = s.replayChanges(changesFileName)
-	// 		if err != nil {
-	// 			qb.Abort(qb.ReplayChangesFailed, err)
-	// 		}
-	// 	}
-	// 	logNumber = recipe.LogNumber
-	// }
-
-	// s.storage, err = storage.NewWriter(storage.WriterOptions{
-	// 	Dir:                 s.dir,
-	// 	LogNumber:           logNumber,
-	// 	AppendToWorkerQueue: s.appendJobToWorkerQueue,
-	// 	FreeList:            s.freeList,
-	// 	Atree:               s.atree,
-	// 	ExitCh:              s.exitCh,
-	// 	WaitGroup:           s.waitGroup,
-	// })
-	// if err != nil {
-	// 	qb.Abort(qb.CreateChangesWriterFailed, err)
-
-	// }
-	// go s.storage.Run()
-
-	// // fileNames, err := s.searchREDOFiles()
-	// // if err != nil {
-	// // 	qb.Abort(qb.SearchREDOFilesFailed, err)
-	// // }
-
-	// // if len(fileNames) > 0 {
-	// // 	for _, fileName := range fileNames {
-	// // 		err = s.replayREDOFile(fileName)
-	// // 		if err != nil {
-	// // 			qb.Abort(qb.ReplayREDOFileFailed, err)
-	// // 		}
-	// // 	}
-
-	// // 	for _, fileName := range fileNames {
-	// // 		err = os.Remove(fileName)
-	// // 		if err != nil {
-	// // 			qb.Abort(qb.RemoveREDOFileFailed, err)
-	// // 		}
-	// // 	}
-	// // }
-
-	// if recipe != nil {
-	// 	if recipe.CompleteSnapshot {
-	// 		err = s.dumpSnapshot(logNumber)
-	// 		if err != nil {
-	// 			qb.Abort(qb.DumpSnapshotFailed, err)
-	// 		}
-	// 	}
-
-	// 	for _, fileName := range recipe.ToDelete {
-	// 		err = os.Remove(fileName)
-	// 		if err != nil {
-	// 			qb.Abort(qb.RemoveRecipeFileFailed, err)
-	// 		}
-	// 	}
-	// }
-}
-
 //
 
 // зробити object?
@@ -283,9 +217,9 @@ func (s *Database) replayChanges(snapshotNumber int) (err error) {
 }
 
 func (s *Database) relayMetricsToMetrics(replayMetrics map[uint32]*ReplayMetric) {
-	for metricID, x := range replayMetrics {
-		s.metrics[metricID] = x.ToMetric()
-	}
+	//for metricID, x := range replayMetrics {
+	//s.metrics[metricID] = x.ToMetric() FIX
+	//}
 }
 
 //func (s *Database) verifySnapshot(fileName string) (_ bool, err error) {
diff --git a/database/helpers.go b/database/helpers.go
index 3e9d503..f0a546b 100644
--- a/database/helpers.go
+++ b/database/helpers.go
@@ -44,28 +44,6 @@ func isFileExist(fileName string) (bool, error) {
 	}
 }
 
-func (s *Database) appendJobToWorkerQueue(job any) {
-	s.mutex.Lock()
-	s.workerQueue = append(s.workerQueue, job)
-	s.mutex.Unlock()
-
-	select {
-	case s.workerSignalCh <- struct{}{}:
-	default:
-	}
-}
-
-func (s *Database) metricRUnlock(metricID uint32) {
-	s.mutex.Lock()
-	s.rLocksToRelease = append(s.rLocksToRelease, metricID)
-	s.mutex.Unlock()
-
-	select {
-	case s.workerSignalCh <- struct{}{}:
-	default:
-	}
-}
-
 func correctToFHD(since, until uint32, firstHourOfDay int) (uint32, uint32) {
 	duration := time.Duration(firstHourOfDay) * time.Hour
 	since = uint32(time.Unix(int64(since), 0).Add(duration).Unix())
diff --git a/database/metric.go b/database/metric.go
index d3b9c4d..42d0028 100644
--- a/database/metric.go
+++ b/database/metric.go
@@ -70,7 +70,7 @@ func (s *_metric) OnMeasuresDeleteCommited(rec storage.MeasuresDeleteCommited) {
 }
 
 // func (s *_metric) startAppendMeasures(req tryAppendMeasuresReq, sendToStorage func(storage.AppendedMeasures)) {
-func (s *_metric) StartAppendMeasures(req tryAppendMeasuresReq, tmp []byte, sendToStorage func(any)) {
+func (s *_metric) StartAppendMeasures(req tryAppendMeasuresReq, tmp []byte, saveToStorage func(any)) {
 	if s.capturedState != nil {
 		s.WaitQueue = append(s.WaitQueue, req)
 	}
@@ -174,7 +174,7 @@ func (s *_metric) StartAppendMeasures(req tryAppendMeasuresReq, tmp []byte, send
 
 	if len(pages) > 0 {
 		// пишу в storage довгим шляхом через redo файл і запис в data файл
-		sendToStorage(storage.MeasuresAppendWithGrow{
+		saveToStorage(storage.MeasuresAppendWithGrow{
 			MetricID:               req.MetricID,
 			LastPageNo:             s.lastPageNo,
 			TimestampsRewindOffset: timestampsRewindOffset,
@@ -191,7 +191,7 @@ func (s *_metric) StartAppendMeasures(req tryAppendMeasuresReq, tmp []byte, send
 		})
 	} else {
 		// короткий шлях - запис лише в storage
-		sendToStorage(storage.MeasuresAppend{
+		saveToStorage(storage.MeasuresAppend{
 			MetricID:               req.MetricID,
 			TimestampsRewindOffset: timestampsRewindOffset,
 			ValuesRewindOffset:     valuesRewindOffset,
diff --git a/database/proc.go b/database/worker.go
similarity index 66%
rename from database/proc.go
rename to database/worker.go
index bb68369..a29ec2e 100644
--- a/database/proc.go
+++ b/database/worker.go
@@ -2,6 +2,7 @@ package database
 
 import (
 	"fmt"
+	"sync"
 
 	qb "gordenko.dev/dima/qb"
 	"gordenko.dev/dima/qb/atree"
@@ -35,50 +36,109 @@ const (
 	DeleteFromAtreeRequired  = 14
 )
 
-func (s *Database) worker() {
+type Worker struct {
+	mutex          sync.Mutex
+	queue          []any
+	signalCh       chan struct{}
+	dir            string
+	snapshotNumber int
+	tmp            []byte
+	metrics        map[uint32]*_metric
+	saveToStorage  func(any)
+	exitCh         chan struct{}
+	waitGroup      *sync.WaitGroup
+}
+
+type WorkerOptions struct {
+	SaveToStorage func(any)
+	Metrics       map[uint32]*_metric
+	Dir           string
+	ExitCh        chan struct{}
+	WaitGroup     *sync.WaitGroup
+}
+
+func NewWorker(opt WorkerOptions) *Worker {
+	return &Worker{
+		signalCh:      make(chan struct{}, 1),
+		dir:           opt.Dir,
+		tmp:           make([]byte, 26),
+		metrics:       opt.Metrics,
+		saveToStorage: opt.SaveToStorage,
+		exitCh:        opt.ExitCh,
+		waitGroup:     opt.WaitGroup,
+	}
+}
+
+func (s *Worker) AddJobToQueue(job any) {
+	s.queue = append(s.queue, job)
+
+	select {
+	case s.signalCh <- struct{}{}:
+	default:
+	}
+}
+
+func (s *Worker) ReleaseRLock(metricID uint32) {
+	s.mutex.Lock()
+	//s.rLocksToRelease = append(s.rLocksToRelease, metricID)
+	s.mutex.Unlock()
+
+	select {
+	case s.signalCh <- struct{}{}:
+	default:
+	}
+}
+
+func (s *Worker) Run() {
 	for {
 		select {
-		case <-s.workerSignalCh:
-			s.DoWork()
+		case <-s.signalCh:
+			s.doWork()
+
+		case <-s.exitCh:
+			fmt.Println("worker done")
+			s.waitGroup.Done()
+			return
 		}
 	}
 }
 
-func (s *Database) DoWork() {
+func (s *Worker) doWork() {
+
 	s.mutex.Lock()
-	rLocksToRelease := s.rLocksToRelease
-	workerQueue := s.workerQueue
-	s.rLocksToRelease = nil
-	s.workerQueue = nil
+	//rLocksToRelease := s.rLocksToRelease
+	queue := s.queue
+	//s.rLocksToRelease = nil
+	s.queue = nil
 	s.mutex.Unlock()
 
-	for _, metricID := range rLocksToRelease {
-		metric, ok := s.metrics[metricID]
-		if !ok {
-			qb.Abort(qb.NoMetricBug,
-				fmt.Errorf("drainQueues: metric %d not found", metricID))
-		}
+	// for _, metricID := range rLocksToRelease {
+	// 	metric, ok := s.metrics[metricID]
+	// 	if !ok {
+	// 		qb.Abort(qb.NoMetricBug,
+	// 			fmt.Errorf("drainQueues: metric %d not found", metricID))
+	// 	}
 
-		if metric.XLock {
-			qb.Abort(qb.XLockBug,
-				fmt.Errorf("drainQueues: xlock is set for the metric %d",
-					metricID))
-		}
+	// 	if metric.XLock {
+	// 		qb.Abort(qb.XLockBug,
+	// 			fmt.Errorf("drainQueues: xlock is set for the metric %d",
+	// 				metricID))
+	// 	}
 
-		if metric.RLocks <= 0 {
-			qb.Abort(qb.NoRLockBug,
-				fmt.Errorf("drainQueues: rlock not set for the metric %d",
-					metricID))
-		}
+	// 	if metric.RLocks <= 0 {
+	// 		qb.Abort(qb.NoRLockBug,
+	// 			fmt.Errorf("drainQueues: rlock not set for the metric %d",
+	// 				metricID))
+	// 	}
 
-		metric.RLocks--
+	// 	metric.RLocks--
 
-		if len(metric.WaitQueue) > 0 {
-			s.processMetricQueue(metricID, metric)
-		}
-	}
+	// 	if len(metric.WaitQueue) > 0 {
+	// 		s.processMetricQueue(metricID, metric)
+	// 	}
+	// }
 
-	for _, untyped := range workerQueue {
+	for _, untyped := range queue {
 		switch req := untyped.(type) {
 		case tryAppendMeasuresReq:
 			s.tryAppendMeasures(req)
@@ -115,7 +175,7 @@ func (s *Database) DoWork() {
 }
 
 // суть у тому що треба запускати запити, пока не зустріну XLock
-func (s *Database) processMetricQueue(metricID uint32, metric *_metric) {
+func (s *Worker) processMetricQueue(metricID uint32, metric *_metric, tmp []byte) {
 	if len(metric.WaitQueue) == 0 {
 		return
 	}
@@ -132,7 +192,7 @@ func (s *Database) processMetricQueue(metricID uint32, metric *_metric) {
 			s.tryGetMetric(req)
 
 		case tryAppendMeasuresReq:
-			//metric.StartAppendMeasures(req, s.storage.Append) FIX
+			metric.StartAppendMeasures(req, tmp, s.saveToStorage)
 
 		case tryDeleteMetricReq:
 			s.startDeleteMetric(metric, req)
@@ -152,12 +212,13 @@ type tryAddMetricReq struct {
 	ResultCh chan byte
 }
 
-func (s *Database) tryAddMetric(req tryAddMetricReq) {
+func (s *Worker) tryAddMetric(req tryAddMetricReq) {
 	_, ok := s.metrics[req.MetricID]
 	if ok {
 		req.ResultCh <- MetricDuplicate
 		return
 	}
+	fmt.Println("metric not found. Success")
 	req.ResultCh <- Succeed // new
 
 	// lockEntry, ok := s.metricLockEntries[req.MetricID]
@@ -171,7 +232,7 @@ func (s *Database) tryAddMetric(req tryAddMetricReq) {
 	// }
 }
 
-func (s *Database) processTryAddMetricReqsImmediatelyAfterDelete(reqs []tryAddMetricReq) {
+func (s *Worker) processTryAddMetricReqsImmediatelyAfterDelete(reqs []tryAddMetricReq) {
 	if len(reqs) == 0 {
 		return
 	}
@@ -197,7 +258,7 @@ type tryGetMetricReq struct {
 	ResultCh chan Metric
 }
 
-func (s *Database) tryGetMetric(req tryGetMetricReq) {
+func (s *Worker) tryGetMetric(req tryGetMetricReq) {
 	metric, ok := s.metrics[req.MetricID]
 	if ok {
 		req.ResultCh <- Metric{
@@ -217,7 +278,7 @@ type tryDeleteMetricReq struct {
 	ResultCh chan tryDeleteMetricResult
 }
 
-func (s *Database) tryDeleteMetric(req tryDeleteMetricReq) {
+func (s *Worker) tryDeleteMetric(req tryDeleteMetricReq) {
 	// FIX
 	// metric, ok := s.metrics[req.MetricID]
 	// if !ok {
@@ -235,7 +296,7 @@ func (s *Database) tryDeleteMetric(req tryDeleteMetricReq) {
 	// }
 }
 
-func (s *Database) startDeleteMetric(metric *_metric, req tryDeleteMetricReq) {
+func (s *Worker) startDeleteMetric(metric *_metric, req tryDeleteMetricReq) {
 	// FIX
 	// s.metricLockEntries[req.MetricID] = &metricLockEntry{
 	// 	XLock: true,
@@ -252,7 +313,7 @@ type tryDeleteMeasuresReq struct {
 	ResultCh chan tryDeleteMeasuresResult
 }
 
-func (s *Database) tryDeleteMeasures(req tryDeleteMeasuresReq) {
+func (s *Worker) tryDeleteMeasures(req tryDeleteMeasuresReq) {
 	// FIX
 	// metric, ok := s.metrics[req.MetricID]
 	// if !ok {
@@ -276,7 +337,7 @@ func (s *Database) tryDeleteMeasures(req tryDeleteMeasuresReq) {
 	// }
 }
 
-func (s *Database) startDeleteMeasures(metric *_metric, req tryDeleteMeasuresReq) {
+func (s *Worker) startDeleteMeasures(metric *_metric, req tryDeleteMeasuresReq) {
 	// FIX
 	// s.metricLockEntries[req.MetricID] = &metricLockEntry{
 	// 	XLock: true,
@@ -294,7 +355,7 @@ func (s *Database) startDeleteMeasures(metric *_metric, req tryDeleteMeasuresReq
 	// }
 }
 
-func (s *Database) onMeasuresAppendCommited(rec storage.MeasuresAppendCommited) {
+func (s *Worker) onMeasuresAppendCommited(rec storage.MeasuresAppendCommited) {
 	metric, ok := s.metrics[rec.MetricID]
 	if !ok {
 		qb.Abort(qb.NoMetricBug,
@@ -304,7 +365,7 @@ func (s *Database) onMeasuresAppendCommited(rec storage.MeasuresAppendCommited)
 	metric.OnMeasuresAppendCommited(rec)
 }
 
-func (s *Database) onMeasuresAppendWithGrowCommited(rec storage.MeasuresAppendWithGrowCommited) {
+func (s *Worker) onMeasuresAppendWithGrowCommited(rec storage.MeasuresAppendWithGrowCommited) {
 	metric, ok := s.metrics[rec.MetricID]
 	if !ok {
 		qb.Abort(qb.NoMetricBug,
@@ -320,7 +381,7 @@ type tryAppendMeasuresReq struct {
 	ResultCh chan tryAppendMeasuresResult
 }
 
-func (s *Database) tryAppendMeasures(req tryAppendMeasuresReq) {
+func (s *Worker) tryAppendMeasures(req tryAppendMeasuresReq) {
 	metric, ok := s.metrics[req.MetricID]
 	if !ok {
 		req.ResultCh <- tryAppendMeasuresResult{
@@ -332,7 +393,7 @@ func (s *Database) tryAppendMeasures(req tryAppendMeasuresReq) {
 		metric.WaitQueue = append(metric.WaitQueue, req)
 		return
 	}
-	//metric.StartAppendMeasures(req, s.storage.Append) FIX
+	metric.StartAppendMeasures(req, s.tmp, s.saveToStorage)
 }
 
 type tryRangeScanReq struct {
@@ -344,7 +405,7 @@ type tryRangeScanReq struct {
 	ResultCh       chan rangeScanResult
 }
 
-func (s *Database) tryRangeScan(req tryRangeScanReq) {
+func (s *Worker) tryRangeScan(req tryRangeScanReq) {
 	metric, ok := s.metrics[req.MetricID]
 	if !ok {
 		req.ResultCh <- rangeScanResult{
@@ -374,7 +435,7 @@ type tryFullScanReq struct {
 	ResultCh       chan fullScanResult
 }
 
-func (s *Database) tryFullScan(req tryFullScanReq) {
+func (s *Worker) tryFullScan(req tryFullScanReq) {
 	metric, ok := s.metrics[req.MetricID]
 	if !ok {
 		req.ResultCh <- fullScanResult{
@@ -402,7 +463,7 @@ type tryListCurrentValuesReq struct {
 	ResultCh       chan struct{}
 }
 
-func (s *Database) tryListCurrentValues(req tryListCurrentValuesReq) {
+func (s *Worker) tryListCurrentValues(req tryListCurrentValuesReq) {
 	for _, metricID := range req.MetricIDs {
 		metric, ok := s.metrics[metricID]
 		if ok {
@@ -418,7 +479,7 @@ func (s *Database) tryListCurrentValues(req tryListCurrentValuesReq) {
 
 ///////////////////////////////////////////////////////
 
-func (s *Database) applyCommits(req storage.Changes) {
+func (s *Worker) applyCommits(req storage.Changes) {
 	for _, untyped := range req.Commits {
 		switch rec := untyped.(type) {
 		case storage.MetricAddCommited:
@@ -458,7 +519,7 @@ func (s *Database) applyCommits(req storage.Changes) {
 	}
 }
 
-func (s *Database) onMetricAddCommited(rec storage.MetricAddCommited) {
+func (s *Worker) onMetricAddCommited(rec storage.MetricAddCommited) {
 	// fix lock
 	_, ok := s.metrics[rec.MetricID]
 	if ok {
@@ -477,7 +538,7 @@ func (s *Database) onMetricAddCommited(rec storage.MetricAddCommited) {
 	// delete(s.metricLockEntries, rec.MetricID)
 }
 
-func (s *Database) addMetric(rec storage.MetricAddRecord) {
+func (s *Worker) addMetric(rec storage.MetricAddRecord) {
 	var (
 		buf     = make([]byte, storage.DataPageSize)
 		databuf = buf[:storage.DataPagePayloadSize]
@@ -491,7 +552,7 @@ func (s *Database) addMetric(rec storage.MetricAddRecord) {
 	}
 }
 
-func (s *Database) onMetricDeleteCommited(rec storage.MetricDeleteCommited) {
+func (s *Worker) onMetricDeleteCommited(rec storage.MetricDeleteCommited) {
 	metric, ok := s.metrics[rec.MetricID]
 	if !ok {
 		qb.Abort(qb.NoMetricBug,
@@ -562,7 +623,7 @@ func (s *Database) onMetricDeleteCommited(rec storage.MetricDeleteCommited) {
 	}
 }
 
-func (s *Database) onMeasuresDeleteCommited(rec storage.MeasuresDeleteCommited) {
+func (s *Worker) onMeasuresDeleteCommited(rec storage.MeasuresDeleteCommited) {
 	metric, ok := s.metrics[rec.MetricID]
 	if !ok {
 		qb.Abort(qb.NoMetricBug,
@@ -581,11 +642,97 @@ func (s *Database) onMeasuresDeleteCommited(rec storage.MeasuresDeleteCommited)
 	// if len(rec.FreePageNumbers) > 0 {
 	// 	s.freeList.AddPages(rec.FreePageNumbers)
 	// }
-	s.doAfterReleaseXLock(rec.MetricID, metric)
+	//s.doAfterReleaseXLock(rec.MetricID, metric)
 }
 
-func (s *Database) doAfterReleaseXLock(metricID uint32, metric *_metric) {
-	if len(metric.WaitQueue) > 0 {
-		s.processMetricQueue(metricID, metric)
-	}
+// func (s *Database) doAfterReleaseXLock(metricID uint32, metric *_metric) {
+// 	if len(metric.WaitQueue) > 0 {
+// 		s.processMetricQueue(metricID, metric)
+// 	}
+// }
+
+func (s *Worker) recovery() {
+	// FIX
+	// advisor, err := recovery.NewRecoveryAdvisor(recovery.RecoveryAdvisorOptions{
+	// 	Dir:            s.dir,
+	// 	VerifySnapshot: s.verifySnapshot,
+	// })
+	// if err != nil {
+	// 	panic(err)
+	// }
+
+	// recipe, err := advisor.GetRecipe()
+	// if err != nil {
+	// 	qb.Abort(qb.GetRecoveryRecipeFailed, err)
+	// }
+
+	// var logNumber int
+
+	// if recipe != nil {
+	// 	if recipe.Snapshot != "" {
+	// 		err = s.loadSnapshot(recipe.Snapshot)
+	// 		if err != nil {
+	// 			qb.Abort(qb.LoadSnapshotFailed, err)
+	// 		}
+	// 	}
+	// 	for _, changesFileName := range recipe.Changes {
+	// 		err = s.replayChanges(changesFileName)
+	// 		if err != nil {
+	// 			qb.Abort(qb.ReplayChangesFailed, err)
+	// 		}
+	// 	}
+	// 	logNumber = recipe.LogNumber
+	// }
+
+	// s.storage, err = storage.NewWriter(storage.WriterOptions{
+	// 	Dir:                 s.dir,
+	// 	LogNumber:           logNumber,
+	// 	AppendToWorkerQueue: s.appendJobToWorkerQueue,
+	// 	FreeList:            s.freeList,
+	// 	Atree:               s.atree,
+	// 	ExitCh:              s.exitCh,
+	// 	WaitGroup:           s.waitGroup,
+	// })
+	// if err != nil {
+	// 	qb.Abort(qb.CreateChangesWriterFailed, err)
+
+	// }
+	// go s.storage.Run()
+
+	// // fileNames, err := s.searchREDOFiles()
+	// // if err != nil {
+	// // 	qb.Abort(qb.SearchREDOFilesFailed, err)
+	// // }
+
+	// // if len(fileNames) > 0 {
+	// // 	for _, fileName := range fileNames {
+	// // 		err = s.replayREDOFile(fileName)
+	// // 		if err != nil {
+	// // 			qb.Abort(qb.ReplayREDOFileFailed, err)
+	// // 		}
+	// // 	}
+
+	// // 	for _, fileName := range fileNames {
+	// // 		err = os.Remove(fileName)
+	// // 		if err != nil {
+	// // 			qb.Abort(qb.RemoveREDOFileFailed, err)
+	// // 		}
+	// // 	}
+	// // }
+
+	// if recipe != nil {
+	// 	if recipe.CompleteSnapshot {
+	// 		err = s.dumpSnapshot(logNumber)
+	// 		if err != nil {
+	// 			qb.Abort(qb.DumpSnapshotFailed, err)
+	// 		}
+	// 	}
+
+	// 	for _, fileName := range recipe.ToDelete {
+	// 		err = os.Remove(fileName)
+	// 		if err != nil {
+	// 			qb.Abort(qb.RemoveRecipeFileFailed, err)
+	// 		}
+	// 	}
+	// }
 }
diff --git a/database_linux b/database_linux
new file mode 100755
index 0000000..c09b0f8
Binary files /dev/null and b/database_linux differ
diff --git a/examples/database/main.go b/examples/database/main.go
index aaa884d..7fc2b9f 100644
--- a/examples/database/main.go
+++ b/examples/database/main.go
@@ -58,7 +58,7 @@ func main() {
 		}
 	}()
 
-	wg.Add(1)
+	//wg.Add(1)
 
 	fmt.Fprintf(logfile, "database %q started on port %d.\n",
 		config.DatabaseName, config.TcpPort)
diff --git a/examples/play/main.go b/examples/play/main.go
new file mode 100644
index 0000000..418842e
--- /dev/null
+++ b/examples/play/main.go
@@ -0,0 +1,567 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"math/rand/v2"
+	"os"
+	"time"
+
+	"gopkg.in/ini.v1"
+	"gordenko.dev/dima/qb"
+	"gordenko.dev/dima/qb/client"
+	"gordenko.dev/dima/qb/proto"
+)
+
+var (
+	metricTypeToName = []string{
+		"",
+		"cumulative",
+		"instant",
+	}
+)
+
+func main() {
+	var (
+		iniFileName string
+	)
+
+	flag.Usage = func() {
+		fmt.Fprint(flag.CommandLine.Output(), helpMessage)
+		fmt.Fprint(flag.CommandLine.Output(), configExample)
+		fmt.Fprintf(flag.CommandLine.Output(), mainUsage, os.Args[0])
+		flag.PrintDefaults()
+	}
+	flag.StringVar(&iniFileName, "c", "requests.ini", "path to *.ini config file")
+	flag.Parse()
+
+	config, err := loadConfig(iniFileName)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	conn, err := client.Connect(config.DatabaseAddr)
+	if err != nil {
+		log.Fatalf("client.Connect(%s): %s\n", config.DatabaseAddr, err)
+	} else {
+		fmt.Println("Connected to database")
+	}
+
+	sendRequests(conn)
+}
+
+// CONFIG FILE
+
+const mainUsage = `Usage:
+	%s -c path/to/config.ini
+
+`
+
+const helpMessage = `Gordenko project. Example requests. Version: 1.0
+created by Dmytro Gordenko, 1.e4.kc6@gmail.com
+`
+
+const configExample = `
+requests.ini example:
+
+databaseAddr    = :12345
+
+`
+
+type Config struct {
+	DatabaseAddr string
+}
+
+func (s Config) String() string {
+	return fmt.Sprintf(`starting options:
+databaseAddr = %s
+`,
+		s.DatabaseAddr)
+}
+
+func loadConfig(iniFileName string) (_ Config, err error) {
+	file, err := ini.Load(iniFileName)
+	if err != nil {
+		return
+	}
+
+	conf := Config{}
+	top := file.Section("")
+
+	conf.DatabaseAddr = top.Key("databaseAddr").String()
+	return conf, nil
+}
+
+func sendRequests(conn *client.Connection) {
+	var (
+		//instantMetricID uint32 = 10000
+		cumulativeMetricID uint32 = 10001
+		fracDigits         byte   = 2
+		err                error
+	)
+
+	//conn.DeleteMetric(instantMetricID)
+	//conn.DeleteMetric(cumulativeMetricID)
+
+	// ADD INSTANT METRIC
+
+	err = conn.AddMetric(proto.AddMetricReq{
+		MetricID:   cumulativeMetricID,
+		MetricType: qb.Instant,
+		FracDigits: fracDigits,
+	})
+	if err != nil {
+		log.Fatalf("conn.AddMetric: %s\n", err)
+	} else {
+		fmt.Printf("\nInstant metric %d added\n", cumulativeMetricID)
+	}
+
+	// GET INSTANT METRIC
+
+	// 	iMetric, err := conn.GetMetric(cumulativeMetricID)
+	// 	if err != nil {
+	// 		log.Fatalf("conn.GetMetric: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf(`
+	// GetMetric:
+	//   metricID: %d
+	//   metricType: %s
+	//   fracDigits: %d
+	// `,
+	// 			iMetric.MetricID, metricTypeToName[iMetric.MetricType], fracDigits)
+	//}
+
+	// APPEND MEASURES
+
+	// 	instantMeasures := GenerateInstantMeasures(62, 220)
+
+	// 	err = conn.AppendMeasures(proto.AppendMeasuresReq{
+	// 		MetricID: instantMetricID,
+	// 		Measures: instantMeasures,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.AppendMeasures: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nAppended %d measures for the metric %d\n",
+	// 			len(instantMeasures), instantMetricID)
+	// 	}
+
+	// 	// LIST INSTANT MEASURES
+
+	// 	lastTimestamp := instantMeasures[len(instantMeasures)-1].Timestamp
+	// 	until := time.Unix(int64(lastTimestamp), 0)
+	// 	since := until.Add(-5 * time.Hour)
+
+	// 	instantList, err := conn.ListInstantMeasures(proto.ListInstantMeasuresReq{
+	// 		MetricID: instantMetricID,
+	// 		Since:    uint32(since.Unix()),
+	// 		Until:    uint32(until.Unix()),
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListInstantMeasures: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListInstantMeasures %s - %s:\n",
+	// 			formatTime(uint32(since.Unix())), formatTime(uint32(until.Unix())))
+	// 		for _, item := range instantList {
+	// 			fmt.Printf("  %s => %.2f\n", formatTime(item.Timestamp), item.Value)
+	// 		}
+	// 	}
+
+	// 	// LIST ALL INSTANT MEASURES
+
+	// 	instantList, err = conn.ListAllInstantMeasures(instantMetricID)
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListAllInstantMeasures: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListAllInstantMeasures (last 15 items):\n")
+	// 		for _, item := range instantList[:15] {
+	// 			fmt.Printf("  %s => %.2f\n", formatTime(item.Timestamp), item.Value)
+	// 		}
+	// 	}
+
+	// 	// LIST INSTANT PERIODS (group by hour)
+
+	// 	until = time.Unix(int64(lastTimestamp+1), 0)
+	// 	since = until.Add(-24 * time.Hour)
+
+	// 	instantPeriods, err := conn.ListInstantPeriods(proto.ListInstantPeriodsReq{
+	// 		MetricID: instantMetricID,
+	// 		Since: proto.TimeBound{
+	// 			Year:  since.Year(),
+	// 			Month: since.Month(),
+	// 			Day:   since.Day(),
+	// 		},
+	// 		Until: proto.TimeBound{
+	// 			Year:  until.Year(),
+	// 			Month: until.Month(),
+	// 			Day:   until.Day(),
+	// 		},
+	// 		GroupBy:        qb.GroupByHour,
+	// 		AggregateFuncs: qb.AggregateMin | qb.AggregateMax | qb.AggregateAvg,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListInstantPeriods: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListInstantPeriods (1 day, group by hour):\n")
+	// 		for _, item := range instantPeriods {
+	// 			fmt.Printf("  %s => min %.2f, max %.2f, avg %.2f\n", formatHourPeriod(item.Period), item.Min, item.Max, item.Avg)
+	// 		}
+	// 	}
+
+	// 	// LIST INSTANT PERIODS (group by day)
+
+	// 	until = time.Unix(int64(lastTimestamp+1), 0)
+	// 	since = until.AddDate(0, 0, -7)
+
+	// 	instantPeriods, err = conn.ListInstantPeriods(proto.ListInstantPeriodsReq{
+	// 		MetricID: instantMetricID,
+	// 		Since: proto.TimeBound{
+	// 			Year:  since.Year(),
+	// 			Month: since.Month(),
+	// 			Day:   since.Day(),
+	// 		},
+	// 		Until: proto.TimeBound{
+	// 			Year:  until.Year(),
+	// 			Month: until.Month(),
+	// 			Day:   until.Day(),
+	// 		},
+	// 		GroupBy:        qb.GroupByDay,
+	// 		AggregateFuncs: qb.AggregateMin | qb.AggregateMax | qb.AggregateAvg,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListInstantPeriods: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListInstantPeriods (7 days, group by day):\n")
+	// 		for _, item := range instantPeriods {
+	// 			fmt.Printf("  %s => min %.2f, max %.2f, avg %.2f\n", formatDayPeriod(item.Period), item.Min, item.Max, item.Avg)
+	// 		}
+	// 	}
+
+	// 	// LIST INSTANT PERIODS (group by month)
+
+	// 	until = time.Unix(int64(lastTimestamp+1), 0)
+	// 	since = until.AddDate(0, 0, -62)
+
+	// 	instantPeriods, err = conn.ListInstantPeriods(proto.ListInstantPeriodsReq{
+	// 		MetricID: instantMetricID,
+	// 		Since: proto.TimeBound{
+	// 			Year:  since.Year(),
+	// 			Month: since.Month(),
+	// 			Day:   since.Day(),
+	// 		},
+	// 		Until: proto.TimeBound{
+	// 			Year:  until.Year(),
+	// 			Month: until.Month(),
+	// 			Day:   until.Day(),
+	// 		},
+	// 		GroupBy:        qb.GroupByMonth,
+	// 		AggregateFuncs: qb.AggregateMin | qb.AggregateMax | qb.AggregateAvg,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListInstantPeriods: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListInstantPeriods (62 days, group by month):\n")
+	// 		for _, item := range instantPeriods {
+	// 			fmt.Printf("  %s => min %.2f, max %.2f, avg %.2f\n", formatMonthPeriod(item.Period), item.Min, item.Max, item.Avg)
+	// 		}
+	// 	}
+
+	// 	// DELETE INSTANT METRIC MEASURES
+
+	// 	err = conn.DeleteMeasures(proto.DeleteMeasuresReq{
+	// 		MetricID: instantMetricID,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.DeleteMeasures: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nInstant metric %d measures deleted\n", instantMetricID)
+	// 	}
+
+	// 	// DELETE INSTANT METRIC
+
+	// 	err = conn.DeleteMetric(instantMetricID)
+	// 	if err != nil {
+	// 		log.Fatalf("conn.DeleteMetric: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nInstant metric %d deleted\n", instantMetricID)
+	// 	}
+
+	// 	// ADD CUMULATIVE METRIC
+
+	// 	err = conn.AddMetric(proto.AddMetricReq{
+	// 		MetricID:   cumulativeMetricID,
+	// 		MetricType: qb.Cumulative,
+	// 		FracDigits: fracDigits,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.AddMetric: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nCumulative metric %d added\n", cumulativeMetricID)
+	// 	}
+
+	// 	// GET CUMULATIVE METRIC
+
+	// 	cMetric, err := conn.GetMetric(cumulativeMetricID)
+	// 	if err != nil {
+	// 		log.Fatalf("conn.GetMetric: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf(`
+	// GetMetric:
+	//   metricID: %d
+	//   metricType: %s
+	//   fracDigits: %d
+	// `,
+	// 			cMetric.MetricID, metricTypeToName[cMetric.MetricType], fracDigits)
+	// 	}
+
+	// 	// APPEND MEASURES
+
+	// 	cumulativeMeasures := GenerateCumulativeMeasures(62)
+
+	// 	err = conn.AppendMeasures(proto.AppendMeasuresReq{
+	// 		MetricID: cumulativeMetricID,
+	// 		Measures: cumulativeMeasures,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.AppendMeasures: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nAppended %d measures for the metric %d\n",
+	// 			len(cumulativeMeasures), cumulativeMetricID)
+	// 	}
+
+	// 	// LIST CUMULATIVE MEASURES
+
+	// 	lastTimestamp = cumulativeMeasures[len(cumulativeMeasures)-1].Timestamp
+	// 	until = time.Unix(int64(lastTimestamp), 0)
+	// 	since = until.Add(-5 * time.Hour)
+
+	// 	cumulativeList, err := conn.ListCumulativeMeasures(proto.ListCumulativeMeasuresReq{
+	// 		MetricID: cumulativeMetricID,
+	// 		Since:    uint32(since.Unix()),
+	// 		Until:    uint32(until.Unix()),
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListCumulativeMeasures: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListCumulativeMeasures %s - %s:\n",
+	// 			formatTime(uint32(since.Unix())), formatTime(uint32(until.Unix())))
+
+	// 		for _, item := range cumulativeList {
+	// 			fmt.Printf("  %s => %.2f\n", formatTime(item.Timestamp), item.Value)
+	// 		}
+	// 	}
+
+	// 	// LIST ALL CUMULATIVE MEASURES
+
+	// 	cumulativeList, err = conn.ListAllCumulativeMeasures(cumulativeMetricID)
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListAllCumulativeMeasures: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListAllCumulativeMeasures (last 15 items):\n")
+	// 		for _, item := range cumulativeList[:15] {
+	// 			fmt.Printf("  %s => %.2f\n", formatTime(item.Timestamp), item.Value)
+	// 		}
+	// 	}
+
+	// 	// LIST CUMULATIVE PERIODS (group by hour)
+
+	// 	until = time.Unix(int64(lastTimestamp+1), 0)
+	// 	since = until.Add(-24 * time.Hour)
+
+	// 	cumulativePeriods, err := conn.ListCumulativePeriods(proto.ListCumulativePeriodsReq{
+	// 		MetricID: cumulativeMetricID,
+	// 		Since: proto.TimeBound{
+	// 			Year:  since.Year(),
+	// 			Month: since.Month(),
+	// 			Day:   since.Day(),
+	// 		},
+	// 		Until: proto.TimeBound{
+	// 			Year:  until.Year(),
+	// 			Month: until.Month(),
+	// 			Day:   until.Day(),
+	// 		},
+	// 		GroupBy: qb.GroupByHour,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListCumulativePeriods: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListCumulativePeriods (1 day, group by hour):\n")
+	// 		for _, item := range cumulativePeriods {
+	// 			fmt.Printf("  %s => end value %.2f, total %.2f\n", formatHourPeriod(item.Period), item.EndValue, item.Total)
+	// 		}
+	// 	}
+
+	// 	// LIST CUMULATIVE PERIODS (group by day)
+
+	// 	until = time.Unix(int64(lastTimestamp+1), 0)
+	// 	since = until.AddDate(0, 0, -7)
+
+	// 	cumulativePeriods, err = conn.ListCumulativePeriods(proto.ListCumulativePeriodsReq{
+	// 		MetricID: cumulativeMetricID,
+	// 		Since: proto.TimeBound{
+	// 			Year:  since.Year(),
+	// 			Month: since.Month(),
+	// 			Day:   since.Day(),
+	// 		},
+	// 		Until: proto.TimeBound{
+	// 			Year:  until.Year(),
+	// 			Month: until.Month(),
+	// 			Day:   until.Day(),
+	// 		},
+	// 		GroupBy: qb.GroupByDay,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListCumulativePeriods: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListCumulativePeriods (7 days, group by day):\n")
+	// 		for _, item := range cumulativePeriods {
+	// 			fmt.Printf("  %s => end value %.2f, total %.2f\n", formatDayPeriod(item.Period), item.EndValue, item.Total)
+	// 		}
+	// 	}
+
+	// 	// LIST CUMULATIVE PERIODS (group by day)
+
+	// 	until = time.Unix(int64(lastTimestamp+1), 0)
+	// 	since = until.AddDate(0, 0, -62)
+
+	// 	cumulativePeriods, err = conn.ListCumulativePeriods(proto.ListCumulativePeriodsReq{
+	// 		MetricID: cumulativeMetricID,
+	// 		Since: proto.TimeBound{
+	// 			Year:  since.Year(),
+	// 			Month: since.Month(),
+	// 			Day:   since.Day(),
+	// 		},
+	// 		Until: proto.TimeBound{
+	// 			Year:  until.Year(),
+	// 			Month: until.Month(),
+	// 			Day:   until.Day(),
+	// 		},
+	// 		GroupBy: qb.GroupByMonth,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.ListCumulativePeriods: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nListCumulativePeriods (62 days, group by month):\n")
+	// 		for _, item := range cumulativePeriods {
+	// 			fmt.Printf("  %s => end value %.2f, total %.2f\n", formatMonthPeriod(item.Period), item.EndValue, item.Total)
+	// 		}
+	// 	}
+
+	// 	// DELETE CUMULATIVE METRIC MEASURES
+
+	// 	err = conn.DeleteMeasures(proto.DeleteMeasuresReq{
+	// 		MetricID: cumulativeMetricID,
+	// 	})
+	// 	if err != nil {
+	// 		log.Fatalf("conn.DeleteMeasures: %s\n", err)
+	// 	} else {
+	// 		fmt.Printf("\nCumulative metric %d measures deleted\n", cumulativeMetricID)
+	// 	}
+
+	// 	// DELETE CUMULATIVE METRIC
+
+	// err = conn.DeleteMetric(cumulativeMetricID)
+	//
+	//	if err != nil {
+	//		log.Fatalf("conn.DeleteMetric: %s\n", err)
+	//	} else {
+	//
+	//		fmt.Printf("\nCumulative metric %d deleted\n", cumulativeMetricID)
+	//	}
+}
+
+const datetimeLayout = "2006-01-02 15:04:05"
+
+func formatTime(timestamp uint32) string {
+	tm := time.Unix(int64(timestamp), 0)
+	return tm.Format(datetimeLayout)
+}
+
+func formatHourPeriod(period uint32) string {
+	tm := time.Unix(int64(period), 0)
+	return tm.Format("2006-01-02 15:00 - 15") + ":59"
+}
+
+func formatDayPeriod(period uint32) string {
+	tm := time.Unix(int64(period), 0)
+	return tm.Format("2006-01-02")
+}
+
+func formatMonthPeriod(period uint32) string {
+	tm := time.Unix(int64(period), 0)
+	return tm.Format("2006-01")
+}
+
+func GenerateCumulativeMeasures(days int) []proto.Measure {
+	var (
+		measures    []proto.Measure
+		minutes     = []int{14, 29, 44, 59}
+		hoursPerDay = 24
+		totalHours  = days * hoursPerDay
+		since       = time.Now().AddDate(0, 0, -days)
+		totalValue  float64
+	)
+
+	for i := range totalHours {
+		hourTime := since.Add(time.Duration(i) * time.Hour)
+		for _, m := range minutes {
+			measureTime := time.Date(
+				hourTime.Year(),
+				hourTime.Month(),
+				hourTime.Day(),
+				hourTime.Hour(),
+				m, // minutes
+				0, // seconds
+				0, // nanoseconds
+				time.Local,
+			)
+
+			measure := proto.Measure{
+				Timestamp: uint32(measureTime.Unix()),
+				Value:     totalValue,
+			}
+			measures = append(measures, measure)
+
+			totalValue += rand.Float64()
+		}
+	}
+	return measures
+}
+
+func GenerateInstantMeasures(days int, baseValue float64) []proto.Measure {
+	var (
+		measures    []proto.Measure
+		minutes     = []int{14, 29, 44, 59}
+		hoursPerDay = 24
+		totalHours  = days * hoursPerDay
+		since       = time.Now().AddDate(0, 0, -days)
+	)
+
+	for i := range totalHours {
+		hourTime := since.Add(time.Duration(i) * time.Hour)
+		for _, m := range minutes {
+			measureTime := time.Date(
+				hourTime.Year(),
+				hourTime.Month(),
+				hourTime.Day(),
+				hourTime.Hour(),
+				m, // minutes
+				0, // seconds
+				0, // nanoseconds
+				time.Local,
+			)
+
+			// value = +-10% from base value
+			fluctuation := baseValue * 0.1
+			value := baseValue + (rand.Float64()*2-1)*fluctuation
+
+			measure := proto.Measure{
+				Timestamp: uint32(measureTime.Unix()),
+				Value:     value,
+			}
+			measures = append(measures, measure)
+		}
+	}
+	return measures
+}
diff --git a/examples/play/play b/examples/play/play
new file mode 100755
index 0000000..b4b8dcf
Binary files /dev/null and b/examples/play/play differ
diff --git a/examples/play/requests.ini b/examples/play/requests.ini
new file mode 100644
index 0000000..9c314ac
--- /dev/null
+++ b/examples/play/requests.ini
@@ -0,0 +1 @@
+databaseAddr = :12345
diff --git a/linux_build.sh b/linux_build.sh
index 0747f5d..6b64115 100755
--- a/linux_build.sh
+++ b/linux_build.sh
@@ -2,10 +2,10 @@ cd examples/database
 env CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o ../../database_linux
 cd -
 
-cd examples/loadtest
-env CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o ../../loadtest_linux
-cd - 
+# cd examples/loadtest
+# env CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o ../../loadtest_linux
+# cd - 
 
-cd examples/requests
-env CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o ../../requests_linux
-cd -
\ No newline at end of file
+# cd examples/requests
+# env CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o ../../requests_linux
+# cd -
\ No newline at end of file
diff --git a/recovery/advisor.go b/recovery/advisor.go
index af08d1e..8013f44 100644
--- a/recovery/advisor.go
+++ b/recovery/advisor.go
@@ -11,18 +11,18 @@ import (
 )
 
 var (
-	reChanges  = regexp.MustCompile(`(\d+)\.changes`)
+	reChanges  = regexp.MustCompile(`(\d+)\.wal`)
 	reSnapshot = regexp.MustCompile(`(\d+)\.snapshot`)
 )
 
-func joinChangesFileName(dir string, logNumber int) string {
-	return filepath.Join(dir, fmt.Sprintf("%d.changes", logNumber))
+func joinWALFileName(dir string, snapshotNumber int) string {
+	return filepath.Join(dir, fmt.Sprintf("%d.wal", snapshotNumber))
 }
 
 type RecoveryRecipe struct {
 	Snapshot         string
 	Changes          []string
-	LogNumber        int
+	SnapshotNumber   int
 	ToDelete         []string
 	CompleteSnapshot bool // флаг - что нужно завершить создание снапшота
 }
@@ -52,8 +52,8 @@ func NewRecoveryAdvisor(opt RecoveryAdvisorOptions) (*RecoveryAdvisor, error) {
 
 type SnapshotChangesPair struct {
 	SnapshotFileName string
-	ChangesFileName  string
-	LogNumber        int
+	WALFileName      string
+	SnapshotNumber   int
 }
 
 func (s *RecoveryAdvisor) getSnapshotChangesPairs() (*SnapshotChangesPair, *SnapshotChangesPair, error) {
@@ -89,21 +89,21 @@ func (s *RecoveryAdvisor) getSnapshotChangesPairs() (*SnapshotChangesPair, *Snap
 		}
 	}
 
-	for logNumber := range numSet {
+	for snapshotNumber := range numSet {
 		var (
 			snapshotFileName string
 			changesFileName  string
 		)
-		if changesSet[logNumber] {
-			changesFileName = joinChangesFileName(s.dir, logNumber)
+		if changesSet[snapshotNumber] {
+			changesFileName = joinWALFileName(s.dir, snapshotNumber)
 		}
-		if snapshotsSet[logNumber] {
-			snapshotFileName = filepath.Join(s.dir, fmt.Sprintf("%d.snapshot", logNumber))
+		if snapshotsSet[snapshotNumber] {
+			snapshotFileName = filepath.Join(s.dir, fmt.Sprintf("%d.snapshot", snapshotNumber))
 		}
 		pairs = append(pairs, SnapshotChangesPair{
-			ChangesFileName:  changesFileName,
+			WALFileName:      changesFileName,
 			SnapshotFileName: snapshotFileName,
-			LogNumber:        logNumber,
+			SnapshotNumber:   snapshotNumber,
 		})
 	}
 
@@ -112,22 +112,22 @@ func (s *RecoveryAdvisor) getSnapshotChangesPairs() (*SnapshotChangesPair, *Snap
 	}
 
 	sort.Slice(pairs, func(i, j int) bool {
-		return pairs[i].LogNumber > pairs[j].LogNumber
+		return pairs[i].SnapshotNumber > pairs[j].SnapshotNumber
 	})
 
 	pair := pairs[0]
-	if pair.ChangesFileName == "" {
+	if pair.WALFileName == "" {
 		return nil, nil, fmt.Errorf("has %d.shapshot file, but %d.changes file not found",
-			pair.LogNumber, pair.LogNumber)
+			pair.SnapshotNumber, pair.SnapshotNumber)
 	}
 
 	if len(pairs) > 1 {
 		prevPair := pairs[1]
-		if prevPair.SnapshotFileName == "" && prevPair.LogNumber != 1 {
+		if prevPair.SnapshotFileName == "" && prevPair.SnapshotNumber != 1 {
 			return &pair, nil, nil
 		}
 
-		if prevPair.ChangesFileName == "" && pair.SnapshotFileName == "" {
+		if prevPair.WALFileName == "" && pair.SnapshotFileName == "" {
 			return &pair, nil, nil
 		}
 		return &pair, &prevPair, nil
@@ -157,14 +157,14 @@ func (s *RecoveryAdvisor) GetRecipe() (*RecoveryRecipe, error) {
 			recipe := &RecoveryRecipe{
 				Snapshot: pair.SnapshotFileName,
 				Changes: []string{
-					pair.ChangesFileName,
+					pair.WALFileName,
 				},
-				LogNumber: pair.LogNumber,
+				SnapshotNumber: pair.SnapshotNumber,
 			}
 
 			if prevPair != nil {
-				if prevPair.ChangesFileName != "" {
-					recipe.ToDelete = append(recipe.ToDelete, prevPair.ChangesFileName)
+				if prevPair.WALFileName != "" {
+					recipe.ToDelete = append(recipe.ToDelete, prevPair.WALFileName)
 				}
 				if prevPair.SnapshotFileName != "" {
 					recipe.ToDelete = append(recipe.ToDelete, prevPair.SnapshotFileName)
@@ -175,55 +175,55 @@ func (s *RecoveryAdvisor) GetRecipe() (*RecoveryRecipe, error) {
 		if prevPair != nil {
 			return s.tryPrevPair(pair, prevPair)
 		}
-		return nil, fmt.Errorf("%d.shapshot is corrupted", pair.LogNumber)
+		return nil, fmt.Errorf("%d.shapshot is corrupted", pair.SnapshotNumber)
 	} else {
 		if prevPair != nil {
 			return s.tryPrevPair(pair, prevPair)
 		} else {
-			if pair.LogNumber == 1 {
+			if pair.SnapshotNumber == 1 {
 				return &RecoveryRecipe{
 					Changes: []string{
-						pair.ChangesFileName,
+						pair.WALFileName,
 					},
-					LogNumber: pair.LogNumber,
+					SnapshotNumber: pair.SnapshotNumber,
 				}, nil
 			} else {
-				return nil, fmt.Errorf("%d.snapshot not found", pair.LogNumber)
+				return nil, fmt.Errorf("%d.snapshot not found", pair.SnapshotNumber)
 			}
 		}
 	}
 }
 
 func (s *RecoveryAdvisor) tryPrevPair(pair, prevPair *SnapshotChangesPair) (*RecoveryRecipe, error) {
-	if prevPair.ChangesFileName == "" {
+	if prevPair.WALFileName == "" {
 		if pair.SnapshotFileName != "" {
 			return nil, fmt.Errorf("%d.shapshot is corrupted and %d.changes not found",
-				pair.LogNumber, prevPair.LogNumber)
+				pair.SnapshotNumber, prevPair.SnapshotNumber)
 		} else {
-			return nil, fmt.Errorf("%d.changes not found", prevPair.LogNumber)
+			return nil, fmt.Errorf("%d.changes not found", prevPair.SnapshotNumber)
 		}
 	}
 
 	if prevPair.SnapshotFileName == "" {
-		if prevPair.LogNumber == 1 {
+		if prevPair.SnapshotNumber == 1 {
 			recipe := &RecoveryRecipe{
 				Changes: []string{
-					prevPair.ChangesFileName,
-					pair.ChangesFileName,
+					prevPair.WALFileName,
+					pair.WALFileName,
 				},
-				LogNumber:        pair.LogNumber,
+				SnapshotNumber:   pair.SnapshotNumber,
 				CompleteSnapshot: true,
 				ToDelete: []string{
-					prevPair.ChangesFileName,
+					prevPair.WALFileName,
 				},
 			}
 			return recipe, nil
 		} else {
 			if pair.SnapshotFileName != "" {
 				return nil, fmt.Errorf("%d.shapshot is corrupted and %d.snapshot not found",
-					pair.LogNumber, prevPair.LogNumber)
+					pair.SnapshotNumber, prevPair.SnapshotNumber)
 			} else {
-				return nil, fmt.Errorf("%d.snapshot not found", pair.LogNumber)
+				return nil, fmt.Errorf("%d.snapshot not found", pair.SnapshotNumber)
 			}
 		}
 	}
@@ -235,19 +235,19 @@ func (s *RecoveryAdvisor) tryPrevPair(pair, prevPair *SnapshotChangesPair) (*Rec
 	}
 
 	if !isVerified {
-		return nil, fmt.Errorf("%d.shapshot is corrupted", prevPair.LogNumber)
+		return nil, fmt.Errorf("%d.shapshot is corrupted", prevPair.SnapshotNumber)
 	}
 
 	recipe := &RecoveryRecipe{
 		Snapshot: prevPair.SnapshotFileName,
 		Changes: []string{
-			prevPair.ChangesFileName,
-			pair.ChangesFileName,
+			prevPair.WALFileName,
+			pair.WALFileName,
 		},
-		LogNumber:        pair.LogNumber,
+		SnapshotNumber:   pair.SnapshotNumber,
 		CompleteSnapshot: true,
 		ToDelete: []string{
-			prevPair.ChangesFileName,
+			prevPair.WALFileName,
 			prevPair.SnapshotFileName,
 		},
 	}
diff --git a/storage/wal_writer.go b/storage/wal_writer.go
index 5ff0712..62d3d05 100644
--- a/storage/wal_writer.go
+++ b/storage/wal_writer.go
@@ -11,7 +11,6 @@ import (
 	"sync"
 
 	"gordenko.dev/dima/qb"
-	"gordenko.dev/dima/qb/atree"
 	"gordenko.dev/dima/qb/freelist"
 )
 
@@ -63,21 +62,19 @@ type Changes struct {
 }
 
 type Writer struct {
-	mutex               sync.Mutex
-	dataPagesCount      uint32
-	indexPagesCount     uint32
-	dataFreeList        *freelist.FreeList
-	indexFreeList       *freelist.FreeList
-	atree               *atree.Atree
+	mutex           sync.Mutex
+	dataPagesCount  uint32
+	indexPagesCount uint32
+	dataFreeList    *freelist.FreeList
+	indexFreeList   *freelist.FreeList
+	//atree               *atree.Atree
 	dir                 string
 	w                   *bytes.Buffer // wal буфер для упаковки даних перед записом на диск
 	wal                 *os.File
 	dataFile            *os.File
 	indexFile           *os.File
-	indexPageSize       int
-	dataPageSize        int
 	input               []any
-	dataPreparer        *WritePreparer
+	writePreparer       *WritePreparer
 	appendToWorkerQueue func(any)
 	written             int64
 	isExited            bool
@@ -87,25 +84,23 @@ type Writer struct {
 }
 
 type WriterOptions struct {
-	IndexPageSize       int
-	DataPageSize        int
-	Dir                 string
-	SnapshotNumber      int // номер журнала
+	Dir string
+	//SnapshotNumber      int // номер журнала
 	AppendToWorkerQueue func(any)
 	DataFreeList        *freelist.FreeList
 	IndexFreeList       *freelist.FreeList
-	Atree               *atree.Atree
-	ExitCh              chan struct{}
-	WaitGroup           *sync.WaitGroup
+	//Atree               *atree.Atree
+	ExitCh    chan struct{}
+	WaitGroup *sync.WaitGroup
 }
 
 func NewWriter(opt WriterOptions) (*Writer, error) {
-	if (opt.IndexPageSize % 2) != 0 {
-		return nil, errors.New("IndexPageSize must be multiple of 2")
-	}
-	if (opt.DataPageSize % 2) != 0 {
-		return nil, errors.New("DataPageSize must be multiple of 2")
-	}
+	// if (opt.IndexPageSize % 2) != 0 {
+	// 	return nil, errors.New("IndexPageSize must be multiple of 2")
+	// }
+	// if (opt.DataPageSize % 2) != 0 {
+	// 	return nil, errors.New("DataPageSize must be multiple of 2")
+	// }
 	if opt.Dir == "" {
 		return nil, errors.New("Dir option is required")
 	}
@@ -118,9 +113,9 @@ func NewWriter(opt WriterOptions) (*Writer, error) {
 	if opt.IndexFreeList == nil {
 		return nil, errors.New("IndexFreeList option is required")
 	}
-	if opt.Atree == nil {
-		return nil, errors.New("Atree option is required")
-	}
+	// if opt.Atree == nil {
+	// 	return nil, errors.New("Atree option is required")
+	// }
 	if opt.ExitCh == nil {
 		return nil, errors.New("ExitCh option is required")
 	}
@@ -128,21 +123,31 @@ func NewWriter(opt WriterOptions) (*Writer, error) {
 		return nil, errors.New("WaitGroup option is required")
 	}
 
+	pageIngester, err := NewPageIngester(PageIngesterOptions{
+		GetIndexPageNumber: s.getIndexPageNumber,
+		GetDataPageNumber:  s.getDataPageNumber,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	writePreparer := NewWritePreparer(WritePreparerOptions{
+		//MinWALBufferSize: 128,
+		PageIngester: pageIngester,
+	})
+
 	s := &Writer{
-		indexPageSize:       opt.IndexPageSize,
-		dataPageSize:        opt.DataPageSize,
 		dir:                 opt.Dir,
 		appendToWorkerQueue: opt.AppendToWorkerQueue,
 		dataFreeList:        opt.DataFreeList,
 		indexFreeList:       opt.IndexFreeList,
-		atree:               opt.Atree,
-		exitCh:              opt.ExitCh,
-		waitGroup:           opt.WaitGroup,
-		signalCh:            make(chan struct{}, 1),
+		writePreparer:       writePreparer,
+		//atree:               opt.Atree,
+		exitCh:    opt.ExitCh,
+		waitGroup: opt.WaitGroup,
+		signalCh:  make(chan struct{}, 1),
 	}
 
-	var err error
-
 	if opt.SnapshotNumber <= 0 {
 		log.Fatalln("FIX FUCK NUMBER")
 	}
@@ -214,7 +219,7 @@ func (s *Writer) packAndWrite() (err error) {
 	// }
 	s.mutex.Unlock()
 
-	prepared := s.dataPreparer.Prepare(input)
+	prepared := s.writePreparer.Prepare(input)
 
 	// 3. Пишу на диск WAL (append)
 	n, err := s.wal.Write(prepared.Packet)
@@ -348,35 +353,35 @@ type PageToWrite struct {
 // writePagesToAtree - записує сторінки в .data та .index файли
 func (s *Writer) WritePagesToAtree(indexPages []PageToWrite, dataPages []PageToWrite) (err error) {
 	for _, p := range dataPages {
-		if len(p.Content) != s.dataPageSize {
+		if len(p.Content) != DataPageSize {
 			return fmt.Errorf("wrong data page size: %d", len(p.Content))
 		}
 		var (
-			off = int(p.PageNo-1) * s.dataPageSize
+			off = int(p.PageNo-1) * DataPageSize
 			n   int
 		)
 		n, err = s.dataFile.WriteAt(p.Content, int64(off))
 		if err != nil {
 			return
 		}
-		if n != s.dataPageSize {
-			return fmt.Errorf("write %d instead of %d", n, s.dataPageSize)
+		if n != DataPageSize {
+			return fmt.Errorf("write %d instead of %d", n, DataPageSize)
 		}
 	}
 	for _, p := range indexPages {
-		if len(p.Content) != s.indexPageSize {
+		if len(p.Content) != IndexPageSize {
 			return fmt.Errorf("wrong index page size: %d", len(p.Content))
 		}
 		var (
-			off = int(p.PageNo-1) * s.indexPageSize
+			off = int(p.PageNo-1) * IndexPageSize
 			n   int
 		)
 		n, err = s.indexFile.WriteAt(p.Content, int64(off))
 		if err != nil {
 			return
 		}
-		if n != s.indexPageSize {
-			return fmt.Errorf("write %d instead of %d", n, s.indexPageSize)
+		if n != IndexPageSize {
+			return fmt.Errorf("write %d instead of %d", n, IndexPageSize)
 		}
 	}
 	return nil
diff --git a/testdir/test.free_data b/testdir/test.free_data
new file mode 100644
index 0000000..e69de29
diff --git a/testdir/test.free_data_delta b/testdir/test.free_data_delta
new file mode 100644
index 0000000..e69de29
diff --git a/testdir/test.free_index b/testdir/test.free_index
new file mode 100644
index 0000000..e69de29
diff --git a/testdir/test.free_index_delta b/testdir/test.free_index_delta
new file mode 100644
index 0000000..e69de29