Add crone jobs in ubuntu

Method I

Put a shell script in one of these folders: /etc/cron.daily, /etc/cron.hourly, /etc/cron.monthlyor /etc/cron.weekly.

Method II

crontab -e

minute hour day-of-month month day-of-week command

every 15 minutes

*/15 * * * * /path/to/command

Hibernate Performance Configuration Tips

Practical

We can check the hibernate behavior via different methods,

1. Profiler on DAO/Session.query() methods.
2. VisualVM for heap usage.
3. Hibernate JMX.
4. RDBMS monitoring tools.

Analyzing Hibernate

1. Using properties like show_sql and format_sql.
2. Log4J configurations,
   1. hibernate.SQL->DEBUG
   2. hibernate.type->TRACE
3. Use P6Spy/Log4JDBC on JDBC connection.

Large Collections

1. Using @BatchSize(size=100) on entities and attributes.
2. Use fetch join
3. Extra lazy collection fetching
   1. @OneToMany(fetch=FetchType.Lazy)
   2. @LazyCollection(LazyCollectionOption.EXTRA)
4. Use “hibernate.jdbc.batch_size” / “hibernate.order_inserts” / “hibernate.order_updates”
5. Use StatelessSession
   1. StatelessSession stateless = session.getSessionFactory().openStatelessSession();

Query Hints

1. Speed up read-only service calls
   • Query query = session.createQuery(“——-”);
   • setReadOnly(true);
2. Query Set Hints
   • setHint(“org.hibernate.fetchSize”, 50);
   • setHint(“org.hibernate.cacheable”, true);
3. Never use second level cache.

Large Updates

1. Use VERSION keyword for optimistic concurrency.
2. Entities are not always necessary,
   1. createQuery(“UPDATE User SET active=false”).executeUpdate();
3. Consider use of stored procedures.

General

• Data and schema outlive your application
• Good indexes makes huge differences
• Stored procedures are not evil
• Do not let hibernate to dictate your schema