BAEL-2456 Hibernate Query Plan Cache

persistence-modules/hibernate5/pom.xml

@@ -73,6 +73,11 @@
             <artifactId>hibernate-jpamodelgen</artifactId>
             <version>${hibernate.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.dropwizard.metrics</groupId>
+            <artifactId>metrics-core</artifactId>
+            <version>${dropwizard-metrics.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -92,6 +97,7 @@
         <h2database.version>1.4.196</h2database.version>
         <assertj-core.version>3.8.0</assertj-core.version>
         <jackson.version>2.9.7</jackson.version>
+        <dropwizard-metrics.version>4.0.5</dropwizard-metrics.version>
     </properties>
 
 </project>

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/HibernateUtil.java

@@ -68,6 +68,11 @@ public class HibernateUtil {
         return sessionFactory;
     }
 
+    public static SessionFactory getSessionFactoryByProperties(Properties properties) throws IOException {
+        ServiceRegistry serviceRegistry = configureServiceRegistry(properties);
+        return makeSessionFactory(serviceRegistry);
+    }
+
     private static SessionFactory makeSessionFactory(ServiceRegistry serviceRegistry) {
         MetadataSources metadataSources = new MetadataSources(serviceRegistry);
 
@@ -119,12 +124,15 @@ public class HibernateUtil {
     }
 
     private static ServiceRegistry configureServiceRegistry() throws IOException {
-        Properties properties = getProperties();
+        return configureServiceRegistry(getProperties());
+    }
+
+    private static ServiceRegistry configureServiceRegistry(Properties properties) throws IOException {
         return new StandardServiceRegistryBuilder().applySettings(properties)
                 .build();
     }
 
-    private static Properties getProperties() throws IOException {
+    public static Properties getProperties() throws IOException {
         Properties properties = new Properties();
         URL propertiesURL = Thread.currentThread()
           .getContextClassLoader()

persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/queryplancache/QueryPlanCacheUnitTest.java

@@ -0,0 +1,105 @@
+package com.baeldung.hibernate.queryplancache;
+
+import com.baeldung.hibernate.HibernateUtil;
+import com.codahale.metrics.Timer;
+import com.codahale.metrics.UniformReservoir;
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.jpa.QueryHints;
+import org.hibernate.query.Query;
+import org.junit.Ignore;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Properties;
+import java.util.concurrent.TimeUnit;
+
+@RunWith(Parameterized.class)
+public class QueryPlanCacheUnitTest {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(QueryPlanCacheUnitTest.class);
+
+    @Parameterized.Parameters
+    public static List<Integer[]> planCacheSize() {
+        List<Integer[]> planCacheSizes = new ArrayList<>();
+
+        planCacheSizes.add(new Integer[]{1});
+        planCacheSizes.add(new Integer[]{2});
+        planCacheSizes.add(new Integer[]{3});
+
+
+        return planCacheSizes;
+    }
+
+    private Timer timer = new Timer(new UniformReservoir(9900));
+
+    private int planCacheSize;
+
+    public QueryPlanCacheUnitTest(int planCacheSize) {
+        this.planCacheSize = planCacheSize;
+    }
+
+    @Test
+    @Ignore
+    public void givenQueryPlanCacheSize_thenCompileQueries() throws IOException {
+        Session session = initSession();
+
+        //warm-up
+        for (int i = 0; i < 9900; i++) {
+            createFindEmployeesByDepartmentNameQuery(session);
+            createFindEmployeesByDesignationQuery(session);
+            createFindDepartmentOfAnEmployeeQuery(session);
+        }
+
+        for (int i = 0; i < 3300; i++) {
+            long startTime = System.nanoTime();
+            createFindEmployeesByDepartmentNameQuery(session);
+            timer.update(System.nanoTime() - startTime, TimeUnit.NANOSECONDS);
+
+            startTime = System.nanoTime();
+            createFindEmployeesByDesignationQuery(session);
+            timer.update(System.nanoTime() - startTime, TimeUnit.NANOSECONDS);
+
+            startTime = System.nanoTime();
+            createFindDepartmentOfAnEmployeeQuery(session);
+            timer.update(System.nanoTime() - startTime, TimeUnit.NANOSECONDS);
+        }
+
+        LOGGER.info("Query Plan Cache Size - {}, Time(Nanoseconds) - {}", planCacheSize, timer.getSnapshot().get95thPercentile());
+
+    }
+
+    private Session initSession() throws IOException {
+        Properties properties = HibernateUtil.getProperties();
+        properties.put("hibernate.query.plan_cache_max_size", planCacheSize);
+        properties.put("hibernate.query.plan_parameter_metadata_max_size", planCacheSize);
+        SessionFactory sessionFactory = HibernateUtil.getSessionFactoryByProperties(properties);
+        return sessionFactory.openSession();
+    }
+
+    private Query createFindEmployeesByDepartmentNameQuery(Session session) {
+        return session.createQuery("SELECT e FROM DeptEmployee e " +
+                "JOIN e.department WHERE e.department.name = :deptName")
+                .setMaxResults(30)
+                .setHint(QueryHints.HINT_FETCH_SIZE, 30);
+    }
+
+    private Query createFindEmployeesByDesignationQuery(Session session) {
+        return session.createQuery("SELECT e FROM DeptEmployee e " +
+                "WHERE e.title = :designation")
+                .setHint(QueryHints.SPEC_HINT_TIMEOUT, 1000);
+    }
+
+    private Query createFindDepartmentOfAnEmployeeQuery(Session session) {
+        return session.createQuery("SELECT e.department FROM DeptEmployee e " +
+                "JOIN e.department WHERE e.employeeNumber = :empId");
+
+    }
+
+}