More qs Flashcards
Name 6 types of database users
- Database Administrators
- Security Officers
- Application Developers
- Application Administrators
- Database Users
- Network Administrators
Name 11 tasks of of a DBA in the context of database management systems
- Capacity planning
- Installation
- Configuration
- Database design
- Migration
- Performance monitoring
- Security
- Troubleshooting
- Backup
- Data recovery
Name 5 activities done by a DBA
- Installing the software
- Creating the databases
- Startup/shutdown of the database
- Managing the data structures
- Managing/creating users and security
Difference between a role and a profile
A profile regulates user access to the database.
Profiles are used to define resource limits and passwords, roles are not
Roles can be assigned to a group of users. Roles regulate user privileges and access to various data structures.
Every user is associated with a profile, whereas users do not have to be associated with a role
Authentication vs authorization
Authentication confirms user identity
Authorization allows users to access a resource (e.g. a table)
A user must authenticate their identity before they can use their authorization permissions
What is a “data warehouse”
Data warehouses are used to support business intelligence and data analytics.
Data warehouses support OLAP (analytical) processes, and they generally collect information from the OLTP (transactional) processes. However, data warehouses collect data from a wide variety of company resources
OLTP databases use data warehouses to offload their data
Data warehouses are used to either conduct or facilitate analysis on historical data.
What does the database listener do?
The listener is a separate process that runs on the oracle host computer. I receives requests and manages traffce to the database server
What is the PGA used for in Oracle? What is the SGA used for? What is the main difference?
The PGA contains data and control information for the given server process
The SGA contains data and control information for reach user and process connected to the database (data buffers, pools for caching)
Each oracle server process is granted an exclusive PGA in memory, whereas SGA caches are shared among sessions
Incremental vs full backup
Full
Full means the database backup strategy is NOT incremental.
Full backups can be made of the entire database or a single file, speed depends on how much is backed up
Incremental
Only modified blocks of data are back up
Classified by level, a level 0 backup performs the same function as full backup
List the steps taken by a DBA when recovering a database using one or more full backups.
- Invoke RMAN, targeting sysbackup
- Startup with no mount
- Restore the control file
- Change the database to mount - Alter database mount
- Use Restore database
- Recover the database
List the steps taken by a DBA when recovering a database using one or more incremental backups.
- Invoke RMAN, targeting sysbackup
- Startup with no mount
- Restore the control file
- Change the database to mount - Alter database mount
- Use Restore database FROM TAG <incremental></incremental>
- Recover the database until SCN <desired></desired>
MTTF stands for:
MTTR stands for:
Mean time to failure
mean time to recover
MTTR is the total amount of time to perform _________ __________ (or preventative maintenance) divided by the number of repairs
Corrective repairs
MTTF evaluates the reliabiity of non-repairable items, and equals the average time expected until the first failure (component, system, assembly). How do we get MTTF
Total hours of operation / total number of units
MTTF predicts
The expected time from repair to the next failure
Equation for MTTR
Maintenance time / total number of repairs
