diff --git a/cmd/postgres_exporter/datasource.go b/cmd/postgres_exporter/datasource.go
index 35abae8b..0f2a6e02 100644
--- a/cmd/postgres_exporter/datasource.go
+++ b/cmd/postgres_exporter/datasource.go
@@ -49,17 +49,19 @@ func (e *Exporter) discoverDatabaseDSNs() []string {
 			continue
 		}
 
-		server, err := e.servers.GetServer(dsn, e.resolutionEnabled)
+		server, err := e.servers.GetServer(dsn)
 		if err != nil {
 			level.Error(logger).Log("msg", "Error opening connection to database", "dsn", loggableDSN(dsn), "err", err)
 			continue
 		}
+		server.dbMtx.Lock()
 		dsns[dsn] = struct{}{}
 
 		// If autoDiscoverDatabases is true, set first dsn as master database (Default: false)
 		server.master = true
 
 		databaseNames, err := queryDatabases(server)
+		server.dbMtx.Unlock()
 		if err != nil {
 			level.Error(logger).Log("msg", "Error querying databases", "dsn", loggableDSN(dsn), "err", err)
 			continue
@@ -100,7 +102,11 @@ func (e *Exporter) discoverDatabaseDSNs() []string {
 }
 
 func (e *Exporter) scrapeDSN(ch chan<- prometheus.Metric, dsn string) error {
-	server, err := e.servers.GetServer(dsn, e.resolutionEnabled)
+	server, err := e.servers.GetServer(dsn)
+	server.dbMtx.Lock()
+	defer server.dbMtx.Unlock()
+
+	level.Debug(logger).Log("msg", "scrapeDSN:"+dsn)
 
 	if err != nil {
 		return &ErrorConnectToServer{fmt.Sprintf("Error opening connection to database (%s): %s", loggableDSN(dsn), err.Error())}
@@ -116,7 +122,7 @@ func (e *Exporter) scrapeDSN(ch chan<- prometheus.Metric, dsn string) error {
 		level.Warn(logger).Log("msg", "Proceeding with outdated query maps, as the Postgres version could not be determined", "err", err)
 	}
 
-	return server.Scrape(ch, e.disableSettingsMetrics)
+	return server.Scrape(ch, e.disableSettingsMetrics, e.resolutionEnabled)
 }
 
 // try to get the DataSource
diff --git a/cmd/postgres_exporter/namespace.go b/cmd/postgres_exporter/namespace.go
index f8aa0c9a..b3e3e056 100644
--- a/cmd/postgres_exporter/namespace.go
+++ b/cmd/postgres_exporter/namespace.go
@@ -183,7 +183,7 @@ func queryNamespaceMapping(server *Server, namespace string, mapping MetricMapNa
 
 // Iterate through all the namespace mappings in the exporter and run their
 // queries.
-func queryNamespaceMappings(ch chan<- prometheus.Metric, server *Server) map[string]error {
+func queryNamespaceMappings(ch chan<- prometheus.Metric, server *Server, res MetricResolution) map[string]error {
 	// Return a map of namespace -> errors
 	namespaceErrors := make(map[string]error)
 
diff --git a/cmd/postgres_exporter/percona_exporter.go b/cmd/postgres_exporter/percona_exporter.go
index 09aa537a..2b371cdc 100644
--- a/cmd/postgres_exporter/percona_exporter.go
+++ b/cmd/postgres_exporter/percona_exporter.go
@@ -2,7 +2,6 @@ package main
 
 import (
 	"crypto/sha256"
-	"database/sql"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -51,7 +50,7 @@ func initializePerconaExporters(dsn []string, servers *Servers) (func(), *Export
 	hrExporter := NewExporter(dsn,
 		append(opts,
 			CollectorName("custom_query.hr"),
-			WithUserQueriesResolutionEnabled(HR),
+			WithUserQueriesEnabled(HR),
 			WithEnabled(*collectCustomQueryHr),
 			WithConstantLabels(*constantLabelsList),
 		)...,
@@ -61,7 +60,7 @@ func initializePerconaExporters(dsn []string, servers *Servers) (func(), *Export
 	mrExporter := NewExporter(dsn,
 		append(opts,
 			CollectorName("custom_query.mr"),
-			WithUserQueriesResolutionEnabled(MR),
+			WithUserQueriesEnabled(MR),
 			WithEnabled(*collectCustomQueryMr),
 			WithConstantLabels(*constantLabelsList),
 		)...,
@@ -71,7 +70,7 @@ func initializePerconaExporters(dsn []string, servers *Servers) (func(), *Export
 	lrExporter := NewExporter(dsn,
 		append(opts,
 			CollectorName("custom_query.lr"),
-			WithUserQueriesResolutionEnabled(LR),
+			WithUserQueriesEnabled(LR),
 			WithEnabled(*collectCustomQueryLr),
 			WithConstantLabels(*constantLabelsList),
 		)...,
@@ -128,21 +127,3 @@ func (e *Exporter) addCustomQueriesFromFile(path string, version semver.Version,
 	// Mark user queries as successfully loaded
 	e.userQueriesError.WithLabelValues(path, hashsumStr).Set(0)
 }
-
-// NewDB establishes a new connection using DSN.
-func NewDB(dsn string) (*sql.DB, error) {
-	fingerprint, err := parseFingerprint(dsn)
-	if err != nil {
-		return nil, err
-	}
-
-	db, err := sql.Open("postgres", dsn)
-	if err != nil {
-		return nil, err
-	}
-	db.SetMaxOpenConns(1)
-	db.SetMaxIdleConns(1)
-
-	level.Info(logger).Log("msg", "Established new database connection", "fingerprint", fingerprint)
-	return db, nil
-}
diff --git a/cmd/postgres_exporter/postgres_exporter.go b/cmd/postgres_exporter/postgres_exporter.go
index fa946892..05aa4d37 100644
--- a/cmd/postgres_exporter/postgres_exporter.go
+++ b/cmd/postgres_exporter/postgres_exporter.go
@@ -452,14 +452,14 @@ func CollectorName(name string) ExporterOpt {
 	}
 }
 
-// WithUserQueriesResolutionEnabled enables resolution for user's queries.
-func WithUserQueriesResolutionEnabled(p MetricResolution) ExporterOpt {
+// WithUserQueriesEnabled enables user's queries.
+func WithUserQueriesEnabled(p MetricResolution) ExporterOpt {
 	return func(e *Exporter) {
 		e.resolutionEnabled = p
 	}
 }
 
-// WithEnabled enables user's queries.
+// WithUserQueriesEnabled enables user's queries.
 func WithEnabled(p bool) ExporterOpt {
 	return func(e *Exporter) {
 		e.enabled = p
@@ -655,31 +655,31 @@ func (e *Exporter) checkMapVersions(ch chan<- prometheus.Metric, server *Server)
 	}
 
 	// Check if semantic version changed and recalculate maps if needed.
-	if semanticVersion.NE(server.lastMapVersion) || server.metricMap == nil {
-		level.Info(logger).Log("msg", "Semantic version changed", "server", server, "from", server.lastMapVersion, "to", semanticVersion)
-		server.mappingMtx.Lock()
+	//if semanticVersion.NE(server.lastMapVersion[e.resolutionEnabled]) || server.metricMap == nil {
+	//	level.Info(logger).Log("msg", "Semantic version changed", "server", server, "from", server.lastMapVersion[e.resolutionEnabled], "to", semanticVersion)
+	server.mappingMtx.Lock()
 
-		// Get Default Metrics only for master database
-		if !e.disableDefaultMetrics && server.master {
-			server.metricMap = makeDescMap(semanticVersion, server.labels, e.builtinMetricMaps)
-			server.queryOverrides = makeQueryOverrideMap(semanticVersion, queryOverrides)
-		} else {
-			server.metricMap = make(map[string]MetricMapNamespace)
-			server.queryOverrides = make(map[string]string)
-		}
-
-		server.lastMapVersion = semanticVersion
-
-		if e.userQueriesPath[e.resolutionEnabled] != "" {
-			// Clear the metric while reload
-			e.userQueriesError.Reset()
-		}
-
-		e.loadCustomQueries(e.resolutionEnabled, semanticVersion, server)
-
-		server.mappingMtx.Unlock()
+	// Get Default Metrics only for master database
+	if !e.disableDefaultMetrics && server.master {
+		server.metricMap = makeDescMap(semanticVersion, server.labels, e.builtinMetricMaps)
+		server.queryOverrides = makeQueryOverrideMap(semanticVersion, queryOverrides)
+	} else {
+		server.metricMap = make(map[string]MetricMapNamespace)
+		server.queryOverrides = make(map[string]string)
 	}
 
+	//server.lastMapVersion[e.resolutionEnabled] = semanticVersion
+
+	if e.userQueriesPath[HR] != "" || e.userQueriesPath[MR] != "" || e.userQueriesPath[LR] != "" {
+		// Clear the metric while reload
+		e.userQueriesError.Reset()
+	}
+
+	e.loadCustomQueries(e.resolutionEnabled, semanticVersion, server)
+
+	server.mappingMtx.Unlock()
+	//}
+
 	// Output the version as a special metric only for master database
 	versionDesc := prometheus.NewDesc(fmt.Sprintf("%s_%s", namespace, staticLabelName),
 		"Version string as reported by postgres", []string{"version", "short_version"}, server.labels)
diff --git a/cmd/postgres_exporter/postgres_exporter_integration_test.go b/cmd/postgres_exporter/postgres_exporter_integration_test.go
index dadee782..b24f76dd 100644
--- a/cmd/postgres_exporter/postgres_exporter_integration_test.go
+++ b/cmd/postgres_exporter/postgres_exporter_integration_test.go
@@ -62,11 +62,7 @@ func (s *IntegrationSuite) TestAllNamespacesReturnResults(c *C) {
 
 	for _, dsn := range s.e.dsn {
 		// Open a database connection
-		db, err := NewDB(dsn)
-		c.Assert(db, NotNil)
-		c.Assert(err, IsNil)
-
-		server, err := NewServer(dsn, db)
+		server, err := NewServer(dsn)
 		c.Assert(server, NotNil)
 		c.Assert(err, IsNil)
 
diff --git a/cmd/postgres_exporter/server.go b/cmd/postgres_exporter/server.go
index fe93cf11..57a08d4f 100644
--- a/cmd/postgres_exporter/server.go
+++ b/cmd/postgres_exporter/server.go
@@ -28,6 +28,7 @@ import (
 // Also it contains metrics map and query overrides.
 type Server struct {
 	db          *sql.DB
+	dbMtx       sync.Mutex
 	labels      prometheus.Labels
 	master      bool
 	runonserver string
@@ -59,12 +60,21 @@ func ServerWithLabels(labels prometheus.Labels) ServerOpt {
 }
 
 // NewServer establishes a new connection using DSN.
-func NewServer(dsn string, db *sql.DB, opts ...ServerOpt) (*Server, error) {
+func NewServer(dsn string, opts ...ServerOpt) (*Server, error) {
 	fingerprint, err := parseFingerprint(dsn)
 	if err != nil {
 		return nil, err
 	}
 
+	db, err := sql.Open("postgres", dsn)
+	if err != nil {
+		return nil, err
+	}
+	db.SetMaxOpenConns(1)
+	db.SetMaxIdleConns(1)
+
+	level.Info(logger).Log("msg", "Established new database connection", "fingerprint", fingerprint)
+
 	s := &Server{
 		db:     db,
 		master: false,
@@ -103,7 +113,7 @@ func (s *Server) String() string {
 }
 
 // Scrape loads metrics.
-func (s *Server) Scrape(ch chan<- prometheus.Metric, disableSettingsMetrics bool) error {
+func (s *Server) Scrape(ch chan<- prometheus.Metric, disableSettingsMetrics bool, res MetricResolution) error {
 	s.mappingMtx.RLock()
 	defer s.mappingMtx.RUnlock()
 
@@ -115,7 +125,7 @@ func (s *Server) Scrape(ch chan<- prometheus.Metric, disableSettingsMetrics bool
 		}
 	}
 
-	errMap := queryNamespaceMappings(ch, s)
+	errMap := queryNamespaceMappings(ch, s, res)
 	if len(errMap) > 0 {
 		err = fmt.Errorf("queryNamespaceMappings returned %d errors", len(errMap))
 		level.Error(logger).Log("msg", "NAMESPACE ERRORS FOUND")
@@ -131,7 +141,6 @@ func (s *Server) Scrape(ch chan<- prometheus.Metric, disableSettingsMetrics bool
 type Servers struct {
 	m       sync.Mutex
 	servers map[string]*Server
-	dbs     map[string]*sql.DB
 	opts    []ServerOpt
 }
 
@@ -139,47 +148,34 @@ type Servers struct {
 func NewServers(opts ...ServerOpt) *Servers {
 	return &Servers{
 		servers: make(map[string]*Server),
-		dbs:     make(map[string]*sql.DB),
 		opts:    opts,
 	}
 }
 
 // GetServer returns established connection from a collection.
-func (s *Servers) GetServer(dsn string, res MetricResolution) (*Server, error) {
+func (s *Servers) GetServer(dsn string) (*Server, error) {
 	s.m.Lock()
 	defer s.m.Unlock()
 	var err error
 	var ok bool
 	errCount := 0 // start at zero because we increment before doing work
 	retries := 1
-	var db *sql.DB
 	var server *Server
 	for {
 		if errCount++; errCount > retries {
 			return nil, err
 		}
-		db, ok = s.dbs[dsn]
+		server, ok = s.servers[dsn]
 		if !ok {
-			db, err = NewDB(dsn)
+			server, err = NewServer(dsn, s.opts...)
 			if err != nil {
 				time.Sleep(time.Duration(errCount) * time.Second)
 				continue
 			}
-			s.dbs[dsn] = db
-		}
-		key := dsn + ":" + string(res)
-		server, ok = s.servers[key]
-		if !ok {
-			server, err = NewServer(dsn, db, s.opts...)
-			if err != nil {
-				time.Sleep(time.Duration(errCount) * time.Second)
-				continue
-			}
-			s.servers[key] = server
+			s.servers[dsn] = server
 		}
 		if err = server.Ping(); err != nil {
-			delete(s.servers, key)
-			delete(s.dbs, dsn)
+			delete(s.servers, dsn)
 			time.Sleep(time.Duration(errCount) * time.Second)
 			continue
 		}