CIS 3050 (Database management)-Chapter 12
Backup facility
a DBMS COPY utility that produces a backup copy (or save)of an entire database or a subset of a database
Information repository
a component that stores metadata that describes an organization's data and data processing resources, manages the total information processing environment, and combines information about an organization's business information and its application portfolio
After image
a copy of a record (or page of memory) after it has been modified
Before image
a copy of a record (or page of memory) before it has been modified
Smart card
a credit card sized plastic card with an embedded microprocessor chip that can store, process, and output electronic data in a secure manner
Transaction
a discrete unit of work that must be completely processed or not processed at all within a computer system. Entering a customer order is an example of a transaction
Checkpoint facility
a facility by which a DBMS periodically refuses to accept any new transactions
Data administration
a high-level function that is responsible for the overall management of the data resources in an organization, including maintaining corporate-wide definitions and standards
Database change log
a log that contains before and after images of records that have been modified by transactions
Deadlock prevention
a method for resolving deadlocks in which user programs must lock all records they require at the beginning of a transaction
Recovery manager
a module of a DBMS that restores the database to a correct condition when a failure occurs and then resumes processing user questions
Two-phase locking protocol
a procedure for acquiring the necessary locks for a transaction in which all necessary locks are acquired before any locks are released,resulting in a growing phase when locks are acquired and a shrinking phase when they are released
Locking
a process in which any data that are retrieved by a user for updating must be locked, or denied to other users, until that update is completed or aborted
Heartbeat inquiry
a query submitted by a DBA to test the current performance of a database or to predict the response time for queries that have promised response times. Also called a canary query
Transaction log
a record of the essential data for each transaction that is processed against the database
Data dictionary
a repository of information about a database that documents data elements of a database
System catalog
a system-created database that describes all database object, including data dictionary information, and also includes user access information
Restore/rerun
a technique that involves reprocessing the days transactions against the backup copy of the database
Forward recovery (roll forward)
a technique that starts with an earlier copy of a database. After images are applied to the database, and the database is quickly moved forward to a later state
Aborted transaction
a transaction in progress that terminates abnormally
Versioning
an approach to concurrency control in which each transaction is restricted to a view of the database as of the time that transaction started, and when a transaction modifies a record, the DBMS creates a new record version of overwriting the old record
Deadlock resolution
an approach to dealing with deadlocks that allows deadlocks to occur but build mechanisms into the DBMS for detecting and breaking the deadlocks
Journalizing facility
an audit trail of transactions and database changes
Deadlock
an impasse that results when two or more transactions have locked a common resource, and each waits for the other to unlock that resource
Inconsistent read problem
an unrepeatable read, one that occurs when occurs when one user reads data that have been partially updated by another user
Authorization rules
controls incorporated in a data management systems that restrict access to data and also restrict the actions that people may take when they access data
User
defined procedures-user exits that allow system designers to define their own security procedures in addition to the authorization rules
Open source DBMS
free DBMS source code software that provides the core functionality of an SQL-compliant DBMS
Database recovery
mechanisms for restoring a database quickly and accurately after loss or damage
Shared lock (S lock
or read lock),a technique that allows other transactions to read but not update a record or another resource
Exclusive lock (X lock
or write lock),a technique that prevents another transaction from reading and therefore updating a record until it is locked
Database security
protection of database data against accidental or intentional loss, destruction, or misuse
Backward recovery (rollback)
the back-out, or undo, of unwanted changes to a database. Before images of the records that have been changed are applied to the database, and the database is returned to an earlier state. Rollback is used to reverse the changes made by transactions that have been aborted, or terminated abnormally.
Encryption
the coding or scrambling of data so that humans cannot read them
Database destruction
the database itself is lost, destroyed, or cannot be read
Locking level (lock granularity
the extent of a database resource that is included with each lock
Transaction boundaries
the logical beginning and end of a transaction
Concurrency control
the process of managing simultaneous operations against a database so that data integrity is maintained and the operations do not interfere with each other in a multiuser environment
Data archiving
the process of moving inactive data to another storage location where it can be accessed when needed