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Database - Interview Questions and Answers for 'Optimistic locking' - 2 question(s) found - Order By Newest

 Q1. What is an optimistic locking ?Database2017-03-29 12:40:27

Ans. It's the way for synchronization wherein we can store version information in the table , so that if the same entity is updated by two transactions, the last to commit changes is informed of the conflict, and does not override the other transaction's work.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     locking  optimistic locking  Synchronization


Related Questions

 What is the difference between these two approaches of creating singleton Class ?

//Double Checked Locking Code
public static Singleton createInstance() {
   if(singleton == null){
      synchronized(Singleton.class) {
         if(singleton == null) {
            singleton = new Singleton();
         }
      }
   }
   return singleton;
}

//Single checked locking code
public static Singleton createInstance() {
   synchronized(Singleton.class) {
      if(singleton == null) {
         singleton = new Singleton();
      }
   }
   return singleton;
}
  What is a BlockingQueue?
 What could be the possible cause for following exception ?

org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect):

What could be the way to fix it ?
 What is a BlockingQueue ?
 Can the double checked locking fail on single processor system ?
 Implement a thread-safe (blocking) queue
 What is the difference between subscribe and blockingSubscribe method ?
 What is optimistic and pessimistic locking ?
 How to build a blocking queue ?


 Q2. What could be the possible cause for following exception ?

org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect):

What could be the way to fix it ?
Hibernate2017-03-29 12:44:00

Ans. This looks like the case for optimistic locking wherein hibernate suspects that the information in table was updated by some other transaction after the entity was loaded by current transaction.

One way is to have synchronized entity state and don't detach the entity. Other could be to merge the entity with the table record rather than just directly persisting the entity.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     StaleObjectStateException  Optimistic locking


Related Questions

 What is the difference between these two approaches of creating singleton Class ?

//Double Checked Locking Code
public static Singleton createInstance() {
   if(singleton == null){
      synchronized(Singleton.class) {
         if(singleton == null) {
            singleton = new Singleton();
         }
      }
   }
   return singleton;
}

//Single checked locking code
public static Singleton createInstance() {
   synchronized(Singleton.class) {
      if(singleton == null) {
         singleton = new Singleton();
      }
   }
   return singleton;
}
  What is a BlockingQueue?
 What is an optimistic locking ?
 What is a BlockingQueue ?
 Can the double checked locking fail on single processor system ?
 Implement a thread-safe (blocking) queue
 What is the difference between subscribe and blockingSubscribe method ?
 What is optimistic and pessimistic locking ?
 How to build a blocking queue ?



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