Question-32

Which of the following scenarios may lead to an irrecoverable error in a database system?

• A transaction writes a data item after it is read by an uncommitted transaction
  
• A transaction reads a data item after it is read by an uncommitted transaction
  
• A transaction reads a data item after it is written by a committed transaction
  
• A transaction reads a data item after it is written by an uncommitted transaction

Answer

• A transaction writes a data item after it is read by an uncommitted transaction
  
• A transaction reads a data item after it is read by an uncommitted transaction
  
• A transaction reads a data item after it is written by a committed transaction
  
• A transaction reads a data item after it is written by an uncommitted transaction