To maintain the integrity of DB2 objects the DBD permits access to only on object at a time. Lock contention happens if several objects are required by contending application processes simultaneously.
Explain transactions, commits and rollbacks in DB2. In DB2 a transaction typically requires a series of updates, insertions and deletions that represent a logical unit of work. A transaction puts an implicit lock on the DB2 data. Programmers can use the COMMIT WORK statement to terminate the transaction creating smaller units for recovery. If the transaction fails DB2 uses the log to roll back values to the start of the transaction or to the preceding commit point.
Deadlock occurs when transactions executing at the same time lock each other out of data that they need to complete their logical units of work. What are the four lockable units for DB2?
Latest Answer : The 4 lock units are Row, Page, Table (if segmented), and Table space. Christine Pastor ...
The three types are shared, update and exclusive. Shared locks allow two or more programs to read simultaneously but not change the locked space. An exclusive lock bars all other users from accessing
Latest Answer : 3 types of locks are SHARE EXCLUSIVE UPDATE ...
An intent lock is at the table level for a segmented tablespace or at the tablespace level for a nonsegmented tablespace. They indicate at the table or tablespace level the kinds of locks at lower levels.
Latest Answer : how to eliminate duplicate rows from a table leaving one from the duplicates ...
Cursor stability means that DB2 takes a lock on the page the cursor is accessing and releases the lock when the cursor moves to another page.
Latest Answer : Cursor stability isolation level ensures that any row that was changed by an application process cannot be read untill committed by that process. It ensures that the current row of every updatable cursor is not changed by other application process. ...
A lock is the mechanism that controls access to data pages and tablespaces.
Latest Answer : Lock is a DB2 mechanism by which DB2 can provide Concurrency and Consistency at the same time(not exactly). Based on the SQL statement DB2 provides different types of locks. They are 1. ...
This is a key concept for any relational database. Isolation level is the manner in which locks are applied and released during a transaction. For DB@ a 'repeatable read' holds all locks untile
Latest Answer : Isolation level means the extent to which the transaction isolates the data is accessed ...
