I am using Hibernate as the JPA provider in a NetBeans 6.9.1 application. I don't know what hibernate ships with 6.9.1.
I have 2 entities, slots and documents where in a given time slot (1 hour typically) there will be multiple documents processed. Furthermore, given a document it may appear in multiple time slots.
What I am seeing are periodic deletes against the join table. In no case am I instigating a delete or remove. Since the join table is dynamically created the rows do not have a version for MVCC and the delete forces a table lock. This, in turn, slows the other threads down and occasionally triggers a 1205, timeout waiting for lock. Consequently, there are 1 1/2 problems here, performing the delete at all is one, dying while waiting for the table lock is another. The underlying db is mysql with the innodb engine (5.1).
package analytics.models;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.Id;
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.JoinColumn;
import javax.persistence.JoinColumns;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.ManyToOne;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Version;
/**
*
* @author walt
*/
@Entity
@Table(name = "Documents", catalog = "Analytics")
@NamedQueries({
@NamedQuery(name = "Document.findAll", query = "SELECT a FROM Document a"),
@NamedQuery(name = "Document.findById", query = "SELECT a FROM Document a WHERE a.docKey.docid = :id"),
@NamedQuery(name = "Document.findByIdDocType", query = "SELECT a FROM Document a WHERE a.docKey.docid = :id and a.docKey.type = :doc")})
public class Document implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
@Basic(optional=false)
@Column(name="id")
private Integer id;
@Basic(optional = false)
@Column(name = "docKey")
private DocumentKey docKey;
@Basic(optional = false)
@Column(name = "inserts")
private int inserts;
@Basic(optional = false)
@Column(name = "deletes")
private int deletes;
@ManyToMany(fetch=FetchType.LAZY)
@JoinTable(name = "slot_doc",
joinColumns = {
@JoinColumn(name="doc_id")
},
inverseJoinColumns = {
@JoinColumn(name="slot_id")
}
)
private Collection<ActivityTimeSlot> times;
@Basic(optional = false)
@Version
@Column(name = "version")
private int version;
public Document() {
times = new ArrayList<ActivityTimeSlot>(0);
inserts = 0;
deletes = 0;
}
@Override
public int hashCode() {
return docKey.hashCode();
}
@Override
public boolean equals(Object object) {
return docKey.equals(object);
}
public int getDeletes() {
return deletes;
}
public void setDeletes(int deletes) {
this.deletes = deletes;
}
public void incrDeletes() {
deletes++;
}
public void incrInserts() {
inserts++;
}
public int getInserts() {
return inserts;
}
public void setInserts(int inserts) {
this.inserts = inserts;
}
public Pair getPair() {
return new Pair(inserts, deletes);
}
@Override
public String toString() {
return docKey.toString();
}
public Collection<ActivityTimeSlot> getTimes() {
return times;
}
public void setTimes(Collection<ActivityTimeSlot>times) {
this.times = times;
}
public DocumentKey getDocKey() {
return docKey;
}
public void setDocKey(DocumentKey docKey) {
this.docKey = docKey;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public void addSlot(ActivityTimeSlot slot) {
slot.getDocuments().add(this);
times.add(slot);
}
}
I see no place there where I would be triggering a delete action. The goal of this code is to initially populate the tables/
If someone would explain what is triggering the delete on the join table I would appreciate it. My goal is to negate whatever reason Hibernate thinks the section of the join table must be removed. When I did catch the sql it was in the order of 'delete from slot_doc where slot_id = 1; Which means it is removing the entire first time slot.
Thanks.
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