diff --git a/full/Changes b/full/Changes
index 85fecd4..2b3bae0 100644
--- a/full/Changes
+++ b/full/Changes
@@ -8,6 +8,7 @@
 - Fixed missing project.version in info web-service
 - Make sure totalResults and other numeric results are numbers (Kupietz)
 - Introduce CQP query language in Koral 0.41
+- Changed DB connection (fixed #670)
 
 # version 0.70.1
 
diff --git a/full/src/main/resources/default-config.xml b/full/src/main/resources/default-config.xml
index 7882650..7cda1cd 100644
--- a/full/src/main/resources/default-config.xml
+++ b/full/src/main/resources/default-config.xml
@@ -112,8 +112,8 @@
 		<!-- <property name="validateOnMigrate" value="false" /> -->
 		<!-- <property name="cleanOnValidationError" value="true" /> -->
 		<property name="locations" value="#{'${jdbc.schemaPath}'.split(',')}"/>
-		<!-- <property name="dataSource" ref="dataSource" /> -->
-		<property name="dataSource" ref="sqliteDataSource" />
+		<property name="dataSource" ref="dataSource" />
+		<!-- <property name="dataSource" ref="sqliteDataSource" /> -->
 		<!-- <property name="dataSource" ref="c3p0DataSource" /> -->
 		<property name="outOfOrder" value="true" />
 	</bean>
@@ -125,8 +125,8 @@
 	<bean id="entityManagerFactory"
 		class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
 		depends-on="flyway">
-		<!-- <property name="dataSource" ref="dataSource" /> -->
-		<property name="dataSource" ref="sqliteDataSource" />
+		<property name="dataSource" ref="dataSource" />
+		<!--  <property name="dataSource" ref="sqliteDataSource" /> -->
 		<!-- <property name="dataSource" ref="c3p0DataSource" /> -->
 
 		<property name="packagesToScan">
diff --git a/full/src/test/java/de/ids_mannheim/korap/web/controller/OAuth2PluginTest.java b/full/src/test/java/de/ids_mannheim/korap/web/controller/OAuth2PluginTest.java
index 4a469bc..5e33841 100644
--- a/full/src/test/java/de/ids_mannheim/korap/web/controller/OAuth2PluginTest.java
+++ b/full/src/test/java/de/ids_mannheim/korap/web/controller/OAuth2PluginTest.java
@@ -4,8 +4,18 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import javax.ws.rs.ProcessingException;
 import javax.ws.rs.client.Entity;
@@ -37,6 +47,9 @@
     private String username = "plugin-user";
     @Autowired
     private InstalledPluginDao pluginDao;
+    
+    private final AtomicBoolean testFailed = new AtomicBoolean(false);
+
 
     @Test
     public void testRegisterPlugin () throws
@@ -220,6 +233,68 @@
                 node.at("/errors/0/0").asInt());
     }
 
+    
+
+    @Test
+    public void testListPluginsConcurrent () throws InterruptedException {
+        ExecutorService executorService = Executors.newFixedThreadPool(3);
+        List<Future<Void>> futures = new ArrayList<>();
+
+        for (int i = 0; i < 3; i++) {
+            futures.add(executorService
+                    .submit(new PluginListCallable("Thread " + (i + 1))));
+        }
+
+        executorService.shutdown();
+        executorService.awaitTermination(2, TimeUnit.SECONDS);
+
+        for (Future<Void> future : futures) {
+            try {
+                future.get(); // This will re-throw any exceptions
+                              // that occurred in threads
+            }
+            catch (ExecutionException e) {
+                fail("Test failed: " + e.getCause().getMessage());
+            }
+        }
+    }
+
+    class PluginListCallable implements Callable<Void> {
+        private final String name;
+
+        public PluginListCallable (String name) {
+            this.name = name;
+        }
+
+        @Override
+        public Void call () {
+            Form form = getSuperClientForm();
+            try {
+                Response response = target().path(API_VERSION).path("plugins")
+                        .request()
+                        .header(Attributes.AUTHORIZATION,
+                                HttpAuthorizationHandler
+                                        .createBasicAuthorizationHeaderValue(
+                                                username, "pass"))
+                        .header(HttpHeaders.CONTENT_TYPE,
+                                ContentType.APPLICATION_FORM_URLENCODED)
+                        .post(Entity.form(form));
+
+                assertEquals(Status.OK.getStatusCode(), response.getStatus());
+
+                String entity = response.readEntity(String.class);
+                JsonNode node = JsonUtils.readTree(entity);
+                assertEquals(2, node.size());
+            }
+            catch (KustvaktException e) {
+                e.printStackTrace();
+                throw new RuntimeException(name, e);
+            }
+            return null;
+        }
+    }
+    
+    
     @Test
     public void testListAllPlugins () throws
             ProcessingException, KustvaktException {
diff --git a/full/src/test/resources/test-config.xml b/full/src/test/resources/test-config.xml
index 4ef13dc..a49795e 100644
--- a/full/src/test/resources/test-config.xml
+++ b/full/src/test/resources/test-config.xml
@@ -104,8 +104,8 @@
 		<property name="cleanOnValidationError" value="true" />
 		<property name="baselineOnMigrate" value="false" />
 		<property name="locations" value="#{'${jdbc.schemaPath}'.split(',')}"/>
-		<property name="dataSource" ref="sqliteDataSource" />
-		<!-- <property name="dataSource" ref="dataSource" /> -->
+		<!-- <property name="dataSource" ref="sqliteDataSource" /> -->
+		<property name="dataSource" ref="dataSource" />
 		<property name="outOfOrder" value="true" />
 	</bean>
 	
@@ -116,8 +116,8 @@
 
 	<bean id="entityManagerFactory"
 		class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
-		<!-- <property name="dataSource" ref="dataSource" /> -->
-		<property name="dataSource" ref="sqliteDataSource" />
+		<property name="dataSource" ref="dataSource" />
+		<!-- <property name="dataSource" ref="sqliteDataSource" /> -->
 		<property name="packagesToScan">
 			<array>
 				<value>de.ids_mannheim.korap.core.entity</value>
diff --git a/full/src/test/resources/test-jdbc.properties b/full/src/test/resources/test-jdbc.properties
index 48f51f5..958cd53 100644
--- a/full/src/test/resources/test-jdbc.properties
+++ b/full/src/test/resources/test-jdbc.properties
@@ -3,7 +3,8 @@
 
 jdbc.database=sqlite
 jdbc.driverClassName=org.sqlite.JDBC
-jdbc.url=jdbc:sqlite::memory:
+#jdbc.url=jdbc:sqlite::memory:
+jdbc.url=jdbc:sqlite::memory:?cache=shared
 #jdbc.url=jdbc:sqlite:testDB.sqlite
 jdbc.username=pc
 jdbc.password=pc