diff --git a/blockbook.go b/blockbook.go
index b12aef36..29e87d73 100644
--- a/blockbook.go
+++ b/blockbook.go
@@ -416,6 +416,11 @@ func connectBlocksParallel(
 	higher uint32,
 	numWorkers int,
 ) error {
+	err := index.ReopenWithBulk(true)
+	if err != nil {
+		return err
+	}
+
 	var wg sync.WaitGroup
 	hch := make(chan string, numWorkers)
 	running := make([]bool, numWorkers)
@@ -444,10 +449,8 @@ func connectBlocksParallel(
 		wg.Add(1)
 		go work(i)
 	}
-	var (
-		err  error
-		hash string
-	)
+	var hash string
+
 	for h := lower; h <= higher; h++ {
 		hash, err = chain.GetBlockHash(h)
 		if err != nil {
@@ -469,7 +472,7 @@ func connectBlocksParallel(
 					}
 					break
 				}
-				if err = index.CompactDatabase(); err != nil {
+				if err = index.CompactDatabase(true); err != nil {
 					break
 				}
 			}
@@ -477,6 +480,11 @@ func connectBlocksParallel(
 	}
 	close(hch)
 	wg.Wait()
+
+	if err == nil {
+		err = index.ReopenWithBulk(false)
+	}
+
 	return err
 }
 
diff --git a/db/rocksdb.go b/db/rocksdb.go
index 69d7ce16..726f3fd9 100644
--- a/db/rocksdb.go
+++ b/db/rocksdb.go
@@ -39,7 +39,7 @@ const (
 
 var cfNames = []string{"default", "height", "outputs", "inputs"}
 
-func openDB(path string) (*gorocksdb.DB, []*gorocksdb.ColumnFamilyHandle, error) {
+func openDB(path string, bulk bool) (*gorocksdb.DB, []*gorocksdb.ColumnFamilyHandle, error) {
 	fp := gorocksdb.NewBloomFilter(10)
 	bbto := gorocksdb.NewDefaultBlockBasedTableOptions()
 	bbto.SetBlockSize(16 << 10)                        // 16kb
@@ -55,6 +55,9 @@ func openDB(path string) (*gorocksdb.DB, []*gorocksdb.ColumnFamilyHandle, error)
 	opts.SetBytesPerSync(1 << 20)    // 1mb
 	opts.SetWriteBufferSize(2 << 30) // 2 gb
 	opts.SetMaxOpenFiles(25000)
+	if bulk {
+		opts.PrepareForBulkLoad()
+	}
 
 	fcOptions := []*gorocksdb.Options{opts, opts, opts, opts}
 
@@ -70,7 +73,7 @@ func openDB(path string) (*gorocksdb.DB, []*gorocksdb.ColumnFamilyHandle, error)
 // needs to be called to release it.
 func NewRocksDB(path string) (d *RocksDB, err error) {
 	glog.Infof("rocksdb: open %s", path)
-	db, cfh, err := openDB(path)
+	db, cfh, err := openDB(path, false)
 	wo := gorocksdb.NewDefaultWriteOptions()
 	ro := gorocksdb.NewDefaultReadOptions()
 	ro.SetFillCache(false)
@@ -474,21 +477,32 @@ func dirSize(path string) (int64, error) {
 // After unsuccessful experiment with CompactRange method (slow and actually fragmenting the db without compacting)
 // the method now closes the db instance and opens it again.
 // This means that during compact nobody can access the dababase!
-func (d *RocksDB) CompactDatabase() error {
+func (d *RocksDB) CompactDatabase(bulk bool) error {
 	size, _ := dirSize(d.path)
 	glog.Info("Compacting database, db size ", size)
+	if err := d.ReopenWithBulk(bulk); err != nil {
+		return err
+	}
+	size, _ = dirSize(d.path)
+	glog.Info("Compacting database finished, db size ", size)
+	return nil
+}
+
+// ReopenWithBulk reopens the database with different settings:
+// if bulk==true, reopens for bulk load
+// if bulk==false, reopens for normal operation
+// It closes and reopens db, nobody can access the database during the operation!
+func (d *RocksDB) ReopenWithBulk(bulk bool) error {
 	err := d.closeDB()
 	if err != nil {
 		return err
 	}
 	d.db = nil
-	db, cfh, err := openDB(d.path)
+	db, cfh, err := openDB(d.path, bulk)
 	if err != nil {
 		return err
 	}
 	d.db, d.cfh = db, cfh
-	size, _ = dirSize(d.path)
-	glog.Info("Compacting database finished, db size ", size)
 	return nil
 }