Author Question: Briefly define the three problems that can occur because of concurrent processing that are addressed ... (Read 138 times)

panfilo · **on:** Jul 7, 2018

Briefly define the three problems that can occur because of concurrent processing that are addressed by resource locking.

What will be an ideal response?

Question 2

In Oracle Database recovery facilities, OnLine ReDo files are maintained on disk and contain the rollback segments from recent database changes.

Indicate whether the statement is true or false

ansleighelindsey · **Reply #1 on:** Jul 7, 2018

Answer to Question 1

The three problems that can occur because of concurrent processing are dirty reads, nonrepeatable reads, and phantom reads. A dirty read occurs when a transaction reads a changed record that has not been committed to the database. If the change is cancelled before it is committed, then the read will contain incorrect data. A nonrepeatable read occurs when a transaction rereads data and finds modifications or deletions caused by another transaction. A phantom read occurs when a transaction rereads data and finds new rows that were inserted by another transaction since the prior read.

Answer to Question 2

TRUE