diff --git a/backend/services/db/main.go b/backend/services/db/main.go
index 2ad6e4aa8..50e160342 100644
--- a/backend/services/db/main.go
+++ b/backend/services/db/main.go
@@ -18,16 +18,17 @@ import (
 	"openreplay/backend/services/db/heuristics"
 )
 
-var pg *cache.PGCache
-
 func main() {
 	log.SetFlags(log.LstdFlags | log.LUTC | log.Llongfile)
 
-	initStats()
-	pg = cache.NewPGCache(postgres.NewConn(env.String("POSTGRES_STRING")), 1000*60*20)
+	// Init database
+	pg := cache.NewPGCache(postgres.NewConn(env.String("POSTGRES_STRING")), 1000*60*20)
 	defer pg.Close()
 
+	// Init modules
 	heurFinder := heuristics.NewHandler()
+	mi := NewMessageInserter(pg)
+	si := NewStatsInserter(pg)
 
 	statsLogger := logger.NewQueueStats(env.Int("LOG_QUEUE_STATS_INTERVAL_SEC"))
 
@@ -40,7 +41,7 @@ func main() {
 		func(sessionID uint64, msg messages.Message, meta *types.Meta) {
 			statsLogger.HandleAndLog(sessionID, meta)
 
-			if err := insertMessage(sessionID, msg); err != nil {
+			if err := mi.insertMessage(sessionID, msg); err != nil {
 				if !postgres.IsPkeyViolation(err) {
 					log.Printf("Message Insertion Error %v, SessionID: %v, Message: %v", err, sessionID, msg)
 				}
@@ -54,7 +55,7 @@ func main() {
 				return
 			}
 
-			err = insertStats(session, msg)
+			err = si.insertStats(session, msg)
 			if err != nil {
 				log.Printf("Stats Insertion Error %v; Session: %v, Message: %v", err, session, msg)
 			}
@@ -62,14 +63,14 @@ func main() {
 			heurFinder.HandleMessage(session, msg)
 			heurFinder.IterateSessionReadyMessages(sessionID, func(msg messages.Message) {
 				// TODO: DRY code (carefully with the return statement logic)
-				if err := insertMessage(sessionID, msg); err != nil {
+				if err := mi.insertMessage(sessionID, msg); err != nil {
 					if !postgres.IsPkeyViolation(err) {
 						log.Printf("Message Insertion Error %v; Session: %v,  Message %v", err, session, msg)
 					}
 					return
 				}
 
-				if err := insertStats(session, msg); err != nil {
+				if err := si.insertStats(session, msg); err != nil {
 					log.Printf("Stats Insertion Error %v; Session: %v,  Message %v", err, session, msg)
 				}
 			})
diff --git a/backend/services/db/messages.go b/backend/services/db/messages.go
index d3e4ae1ed..2adca61c8 100644
--- a/backend/services/db/messages.go
+++ b/backend/services/db/messages.go
@@ -1,68 +1,77 @@
 package main
 
 import (
+	"openreplay/backend/pkg/db/cache"
 	. "openreplay/backend/pkg/messages"
 )
 
-func insertMessage(sessionID uint64, msg Message) error {
+type MessageInserter struct {
+	pg *cache.PGCache
+}
+
+func NewMessageInserter(pg *cache.PGCache) *MessageInserter {
+	return &MessageInserter{pg: pg}
+}
+
+func (mi *MessageInserter) insertMessage(sessionID uint64, msg Message) error {
 	switch m := msg.(type) {
 	// Common
 	case *Metadata:
-		return pg.InsertMetadata(sessionID, m)
+		return mi.pg.InsertMetadata(sessionID, m)
 	case *IssueEvent:
-		return pg.InsertIssueEvent(sessionID, m)
+		return mi.pg.InsertIssueEvent(sessionID, m)
 		//TODO: message adapter (transformer) (at the level of pkg/message) for types:
 	// case *IOSMetadata, *IOSIssueEvent and others
 
 	// Web
 	case *SessionStart:
-		return pg.InsertWebSessionStart(sessionID, m)
+		return mi.pg.InsertWebSessionStart(sessionID, m)
 	case *SessionEnd:
-		return pg.InsertWebSessionEnd(sessionID, m)
+		return mi.pg.InsertWebSessionEnd(sessionID, m)
 	case *UserID:
-		return pg.InsertWebUserID(sessionID, m)
+		return mi.pg.InsertWebUserID(sessionID, m)
 	case *UserAnonymousID:
-		return pg.InsertWebUserAnonymousID(sessionID, m)
+		return mi.pg.InsertWebUserAnonymousID(sessionID, m)
 	case *CustomEvent:
-		return pg.InsertWebCustomEvent(sessionID, m)
+		return mi.pg.InsertWebCustomEvent(sessionID, m)
 	case *ClickEvent:
-		return pg.InsertWebClickEvent(sessionID, m)
+		return mi.pg.InsertWebClickEvent(sessionID, m)
 	case *InputEvent:
-		return pg.InsertWebInputEvent(sessionID, m)
+		return mi.pg.InsertWebInputEvent(sessionID, m)
 		// Unique Web messages
 	// case *ResourceEvent:
 	// 	return pg.InsertWebResourceEvent(sessionID, m)
 	case *PageEvent:
-		return pg.InsertWebPageEvent(sessionID, m)
+		return mi.pg.InsertWebPageEvent(sessionID, m)
 	case *ErrorEvent:
-		return pg.InsertWebErrorEvent(sessionID, m)
+		return mi.pg.InsertWebErrorEvent(sessionID, m)
 	case *FetchEvent:
-		return pg.InsertWebFetchEvent(sessionID, m)
+		return mi.pg.InsertWebFetchEvent(sessionID, m)
 	case *GraphQLEvent:
-		return pg.InsertWebGraphQLEvent(sessionID, m)
+		return mi.pg.InsertWebGraphQLEvent(sessionID, m)
 
 		// IOS
 	case *IOSSessionStart:
-		return pg.InsertIOSSessionStart(sessionID, m)
+		return mi.pg.InsertIOSSessionStart(sessionID, m)
 	case *IOSSessionEnd:
-		return pg.InsertIOSSessionEnd(sessionID, m)
+		return mi.pg.InsertIOSSessionEnd(sessionID, m)
 	case *IOSUserID:
-		return pg.InsertIOSUserID(sessionID, m)
+		return mi.pg.InsertIOSUserID(sessionID, m)
 	case *IOSUserAnonymousID:
-		return pg.InsertIOSUserAnonymousID(sessionID, m)
+		return mi.pg.InsertIOSUserAnonymousID(sessionID, m)
 	case *IOSCustomEvent:
-		return pg.InsertIOSCustomEvent(sessionID, m)
+		return mi.pg.InsertIOSCustomEvent(sessionID, m)
 	case *IOSClickEvent:
-		return pg.InsertIOSClickEvent(sessionID, m)
+		return mi.pg.InsertIOSClickEvent(sessionID, m)
 	case *IOSInputEvent:
-		return pg.InsertIOSInputEvent(sessionID, m)
+		return mi.pg.InsertIOSInputEvent(sessionID, m)
 		// Unique IOS messages
 	case *IOSNetworkCall:
-		return pg.InsertIOSNetworkCall(sessionID, m)
+		return mi.pg.InsertIOSNetworkCall(sessionID, m)
 	case *IOSScreenEnter:
-		return pg.InsertIOSScreenEnter(sessionID, m)
+		return mi.pg.InsertIOSScreenEnter(sessionID, m)
 	case *IOSCrash:
-		return pg.InsertIOSCrash(sessionID, m)
+		return mi.pg.InsertIOSCrash(sessionID, m)
 	}
 	return nil // "Not implemented"
 }
diff --git a/backend/services/db/stats.go b/backend/services/db/stats.go
index 2c3a5da38..7069b8656 100644
--- a/backend/services/db/stats.go
+++ b/backend/services/db/stats.go
@@ -1,23 +1,28 @@
 package main
 
 import (
+	"openreplay/backend/pkg/db/cache"
 	. "openreplay/backend/pkg/db/types"
 	. "openreplay/backend/pkg/messages"
 )
 
-func initStats() {
-	// noop
+type StatsInserter struct {
+	pg *cache.PGCache
 }
 
-func insertStats(session *Session, msg Message) error {
+func NewStatsInserter(pg *cache.PGCache) *StatsInserter {
+	return &StatsInserter{pg: pg}
+}
+
+func (si *StatsInserter) insertStats(session *Session, msg Message) error {
 	switch m := msg.(type) {
 	// Web
 	case *PerformanceTrackAggr:
-		return pg.InsertWebStatsPerformance(session.SessionID, m)
+		return si.pg.InsertWebStatsPerformance(session.SessionID, m)
 	case *ResourceEvent:
-		return pg.InsertWebStatsResourceEvent(session.SessionID, m)
+		return si.pg.InsertWebStatsResourceEvent(session.SessionID, m)
 	case *LongTask:
-		return pg.InsertWebStatsLongtask(session.SessionID, m)
+		return si.pg.InsertWebStatsLongtask(session.SessionID, m)
 
 		// IOS
 		// case *IOSPerformanceAggregated: