Your score increases as you pick a category, fill out a long description and add more tags.Your score increases as you pick a category, fill out a long description and add more tags.

1. DBMS Functions
Data, Storage, Retrieval, and Update
• Provides users with the ability to store,
retrieve, and update the data that are in the
database.

2. DBMS Functions
Shared Update
• Ensures accuracy when several users are
updating the database at the same time.

3. Avoiding Inconsistent Data
• Prohibit shared update.
• Use batch processing
• Lock other users from accessing records
that are being updated by another.

4. Concurrency Control
• The DBMS must prevent or overcome
the interference of transactions of
multiple users
• Locking
– different levels of granularity (records to tables)

5. Avoiding the Problem
• Two-Phase Locking
– Locks are held until all the required updates have been
completed.
• Deadlock
– Occurs when two users hold more than one lock at a
time.
• Locking on PC-Based DBMSs
– Usually much more limited than locking facilities
provided by mainframe DBMSs.

6. Record Locking
• Deadlock prevention
• Deadlock resolution

7. Avoiding the Problem
• Timestamping
– The DBMS assigns to each database update the
unique time when the update started, called a
timestamp.
– Avoids the need to lock rows and eliminates the
processing time needed to apply and release
locks; also detects and resolves deadlocks.

8. Backup and Recovery
• Provides a mechanism for recovering the
database in the event that the database is
damaged in any way.
• The process of returning the database to a
correct state is called recovery.
• Periodically making a copy of the database
is called backup.

9. Replication
• A way to manage copies of the same data at
multiple locations.

10. Security
• The protection of the database against
unauthorized access.
– Passwords
– Encryption
– Views

11. Integrity
• Integrity constraints, or conditions, fall into
four categories:
– Data type
– Legal values
– Format
– Key constraints

12. Integrity Constraints in a DBMS

13. Data Independence
• Facilities that allow programs to be
independent of the structure of the database.
– Addition of a field
– Changing the length of a field
– Creating a new index
– Adding or changing a relationship

14. ACID properties
• Atomic
– all of a transaction should be executed or none
• Consistent
– the database should be in a “consistent” state after the
transaction is completed
• Isolated
– Updates of concurrent transactions should be concealed
from each other, till committed
• Durable
– once a transaction commits, its updates survive even if
there is a subsequent system crash