1. Unauthorized or unintended activity or misuse by authorized database users, database administrators, or network/systems managers, or by unauthorized users or hackers (e.g. inappropriate access to sensitive data, metadata or functions within databases, or inappropriate changes to the database programs, structures or security configurations);
2. Malware infections causing incidents such as unauthorized access, leakage or disclosure of personal or proprietary data, deletion of or damage to the data or programs, interruption or denial of authorized access to the database, attacks on other systems and the unanticipated failure of database services;
3. Overloads, performance constraints and capacity issues resulting in the inability of authorized users to use databases as intended;
4. Physical damage to database servers caused by computer room fires or floods, overheating, lightning, accidental liquid spills, static discharge, electronic breakdowns/equipment failures and obsolescence;
5. Design flaws and programming bugs in databases and the associated programs and systems, creating various security vulnerabilities (e.g. unauthorized privilege escalation), data loss/corruption, performance degradation etc.;
6. Data corruption and/or loss caused by the entry of invalid data or commands, mistakes in database or system administration processes, sabotage/criminal damage etc.
Application of Data Security
In above example, transparent data encryption enables you to encrypt sensitive data, such as credit card numbers, stored in table columns. Encrypted data is transparently decrypted for a database user who has access to the data. Transparent data encryption helps protect data stored on media in the event that the storage media or data file gets stolen.
Above diagram illustrates how access control and encryption work together to provide data Security
Recovery
The process of restoring the database to a correct state in the event of a failure
The storage of data generally includes four different types of media with an increasing degree of reliability:
• Main memory
• Magnetic disk
• Magnetic tape
• Optical disk
Recovery Technique
• Maintain a log file containing transactions records that identify the start/end of transactions and the before-and after-images of the write operation.
• Using deferred update, writes are done initially to the log only and log records are used to perform actual updates to the database.
• If the system fails, it examines the log to determine which transactions it needs to redo, but there is no need to undo any writes.
• Using immediate updates, an update may be made to the database itself any time after a long record is written. The log can be used to undo and redo transactions in the event of failure.
Recovery Application
The Active/Passive pattern is the choice that many companies favor. This pattern provides improvements to the RTO with a relatively small increase in cost over the redeploy pattern. In this scenario, there is again a primary and a secondary Datacenter. All of the traffic goes to the active deployment on the primary datacenter. The secondary datacenter is better prepared for disaster recovery because the database is running on both datacenters. Additionally, there is a synchronization mechanism in place between them. This standby approach can involve two variations: a database-only approach or a complete deployment in the secondary data center.
Concurrency
Its mean “Many transactions - at the same time and Databases shared!”
• So: Transactions must be isolated => need of concurrency control to ensure no interference.
• We will look at:
– 3 classic problems on concurrent access
– Locking mechanism
– Deadlock resolution
Three classic problems
PB: two (more) transactions read / write on the same part of the db. Although transactions execute correctly, results may interleave in diff ways
3 classic problems
• Lost Update
• Uncommitted Dependency
• Inconsistent Analysis
Example of concurrency
Best Example of Data concurrency is Ticket booking transaction
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