Hi,
I am working on a Hibernate issue, which involves 2 separate Entity beans defined separately in their own classes:
- Store
- StoreServer
Note that a Store will have more than one StoreServer - hence the use of the @OneToMany annotation. Please see the code snippets as follows:
Store:
Code:
@Entity
@Table(name="Store")
public class Store implements Serializable {
/**
* Serializable class - generated UID
*/
private static final long serialVersionUID = 5644190852867691168L;
@Id
@Column(name="STORE_NO", nullable=false)
private int storeNumber;
@Column(name="STORE_NAME", nullable=false)
private String storeName;
@Column(name="STORE_PHONE", nullable=false)
private String storePhone;
//other Store fields...
@OneToMany(fetch = FetchType.EAGER)
@JoinColumn(name="STORE_NO", insertable=false, updatable=false)
private List<StoreServer> storeServers = new ArrayList<StoreServer>();
//getters and setters
StoreServer:
Code:
@Entity
@Table(name="Store_Server")
public class StoreServer implements Serializable {
/**
* Serializable class - generated UID
*/
private static final long serialVersionUID = -5410564578856243437L;
@Id
private StoreServerPK storeServerPK;
@Column(name="IP_ADDRESS", nullable=true)
private String ipAddress;
//other StoreServer fields...getters and setters
Since StoreServer has a composite Primary Key, here is StoreServerPK:
Code:
@Embeddable
public class StoreServerPK implements Serializable {
/**
* Serializable class - generated UID
*/
private static final long serialVersionUID = -1401889029390423604L;
@Column(name="STORE_NO", nullable=false)
protected int storeNumber;
@Column(name="SERVER_NO", nullable=false)
protected String serverNumber;
//getters and setters
At present, I am getting the correct results, but the performance is unacceptably SLOW. I have switched on logging in Hibernate and I can see that a separate SELECT query is being run for each Store Entity in order to obtain the associated StoreServer records.
Currently, in the logs, I see a single SELECT statement to obtain the Store records (more than 200 results returned). Then for each store, a new SELECT statement to get the StoreServer records. My question is...Why is Hibernate not doing a join (running one query)?
Please could I get some help on how to tell Hibernate to run a single query, using a JOIN?
Thanks
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