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[英]JPA: How to improve performance in persistance of OneToMany relationships
[英]How to improve performance of Updating data using JPA
我正在使用EJB和容器管理的EM(對於本地測試,我將在此處創建em)。 我有一個需要根據某些條件更新數據庫的要求,我的問題是Update需要很長時間 ,如何減少它?
我嘗試了兩種方法1>更新查詢2>在實體中更新
如果我做任何錯誤或存在任何其他方法,請告訴我。
注意:更新代碼如下
public class Test {
private static final int OaOnaccount = 0;
private static final int ArrayList = 0;
private static EntityManagerFactory emf;
private static EntityManager em;
static int TEST_SIZE = 20000/4;
public static void main(String[] args) {
// createBulk();
createUpdateQuery();
// update();
}
private static void createUpdateQuery() {
long st = System.currentTimeMillis();
emf = Persistence.createEntityManagerFactory("Jpa");
em = emf.createEntityManager();
System.out.println("---- createUpdateQuery ---");
EntityTransaction tx = em.getTransaction();
Query query = em.createQuery("SELECT p FROM OaOnaccount p");
tx.begin();
java.util.Vector<OaOnaccount> list = (java.util.Vector<OaOnaccount>) query.getResultList();
for (int i = 0; i < list.size(); i++) {
String m = 1000000 + (i / 20) + "";
query = em
.createQuery("UPDATE OaOnaccount p SET p.status='COMPLETED', p.billingDoc='12112ABCS' WHERE p.crDrIndicator='H' AND p.status ='OPEN' AND p.documentNumber="+ m);
query.executeUpdate();
}
em.flush();
tx.commit();
long et = System.currentTimeMillis();
System.out.println("Test.createUpdateQuery() Time " + (et - st));
}
private static void update() {
long st = System.currentTimeMillis();
emf = Persistence.createEntityManagerFactory("Jpa");
em = emf.createEntityManager();
System.out.println("---- update ---");
EntityTransaction tx = em.getTransaction();
Query query = em.createQuery("SELECT p FROM OaOnaccount p");
tx.begin();
java.util.Vector<OaOnaccount> list = (java.util.Vector<OaOnaccount>) query
.getResultList();
for (int i = 0; i < list.size(); i++) {
String m = 1000000 + (i / 20) + "";
query = em
.createQuery("SELECT p FROM OaOnaccount p WHERE p.crDrIndicator='H' AND p.status ='OPEN' AND p.documentNumber="
+ m);
java.util.Vector<OaOnaccount> listEn = (java.util.Vector<OaOnaccount>) query
.getResultList();
for (int j = 0; j < listEn.size(); j++) {
listEn.get(j).setBillingDoc("12112ABCS");
listEn.get(j).setStatus("COMPLETED");
}
}
em.flush();
tx.commit();
long et = System.currentTimeMillis();
System.out.println("Test.Update() Time " + (et - st));
}
public static void createBulk() {
long st = System.currentTimeMillis();
emf = Persistence.createEntityManagerFactory("Jpa");
em = emf.createEntityManager();
System.out.println("-------");
EntityTransaction tx = em.getTransaction();
tx.begin();
for (int i = 0; i < TEST_SIZE; i++) {
OaOnaccount entity = new OaOnaccount();
entity.setId("ID-" + i);
entity.setCrDrIndicator(i % 2 == 0 ? "H" : "S");
entity.setDocumentNumber(1000000 + (i / 20) + "");
entity.setAssignment(89000000 + (i / 27) + "");
entity.setStatus("OPEN");
em.persist(entity);
}
em.flush();
tx.commit();
long et = System.currentTimeMillis();
System.out.println("Test.createBulk() Time " + (et - st));
}
}
您應該每n次執行一次em.flush()。 例如,如果n-太低,則更多的db交互次數因此會降低執行代碼的速度。 如果n-太高,則太多對象將駐留在內存中,因此更多交換將導致執行代碼的速度變慢。 請適當選擇n值並將其應用。 我嘗試更新240萬條記錄,但遇到了同樣的問題。
for (int i = 0; i < list.size(); i++) {
String m = 1000000 + (i / 20) + "";
query = em
.createQuery("UPDATE OaOnaccount p SET p.status='COMPLETED', p.billingDoc='12112ABCS' WHERE p.crDrIndicator='H' AND p.status ='OPEN' AND p.documentNumber="+ m);
query.executeUpdate();
if(i%100==0){// 100 to just to show example-- % operation is costly. you can use better logic to flush. frequent flushing is necessary
em.flush();
}
}
檢查OaOnaccount表上的索引,特別要確保p.status
和p.documentNumber
都有索引,甚至最好使用(status, documentNumber)
的組合索引
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