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