Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
database chapter 7
| Question | Answer |
|---|---|
| Updating data in a database includes what three things? | -adding new records, -changing existing records, - deleting existing records |
| Data about the data in a database or ____ includes table descriptions and field secriptions. | metadata |
| The ___ can authorize other users access to some catalog tables as necessary. | DBA(Database Administrator) |
| Enterprise DBMS's such as Oracle and DB2 often have a catalog called a ____. | data dictionary |
| _____ occurs when multiple users make updates to the same database at the same time. | Concurrent update |
| When a user needs to update the database, that database itself is not updated. Instead the update is recorded in a seperate file. Periodically, a single update program reads the batch of records in this file and performs the updates. This process is? | batch processing |
| One strategy to avoid concurrent updates is to process an update completely before it beings processing the next update. To accomplish this, many DBMS's use ___. | locking |
| __ denies other users access to data while the DBMS processes one user's updates to the database. | locking |
| Each task that a user completes is called a _____. | transaction |
| A ___ is a set of steps completed by a DBMS to accomplish a single task. | transaction |
| An approach to locking that is used to manage concurrent updates in which there are two phases. | two-phase locking |
| What are the two phases of two-phase locking? | growing phase, shrinking phase |
| A ___ phase in which the DBMS locks more rows and releases none of the locks. | growing |
| A _____ phase in which the DBMS releases all the locks and aquires no new locks. | shrinking |
| A situation in which two or more database users are each waiting to use resources that are held by the others. What are the two names for this situation? | deadlock or deadly embrace |
| One strategy for managing deadlock is to let deadlock occur and thenhave the DBMS ... | detect and break any deadlock. |
| After the DBMS detects deadlock, the DBMS must rbeak the deadlock. To break the deadlock, the DBMS chooses one deadlocked user to be the ___. | victem |
| Guidelines devices for writing programs for concurrent updates:If an update transaction must lock more than one row in the same table, you must ____. | lock the entire table |
| Because there is no facility to detect and handle deadlocks, you must try to ___ ___. | prevent them. |
| An alternative to two-phase locking is: | timestamping |
| With ___, the DBMS assigns to each database update the unique time when the update started; this time is called a ____. | Timestamping, timestamp |
| What are the pros of timestamping? | (1)avoids the need to lock rows (2)eliminates the processing time needed to apply and release locks (3) less processing time needed to detect and resolve deadlocks. |
| What are the cons of timestamping? | (1)additional memory and disk space(2)extra processing time to update the timestamp values. |
| A DBMS must provide methods to ___ a database in the event the databse is damaged in any way. | recover |
| ___ is the process of returning the database to a state that is known to be corret from a state known to be incorrect. | recovery |
| If the data in a database has been damaged, the simplest applraoch to recovery involves periodically making a copy of the database(called a ___ or a ___). | backup, save |
| If the database was backed up at 8 and at 11 the database is destroyed or damaged, what feature can you use to avoid all the workers have to redo their work? | journaling |
| Journaling involves maintaining a __ or ___ of all updates to the database. | journal, log |
| A log also includes a record of what the data in the row looked like in the database before the update(called a ___ ___.) | before image |
| A log also includes a record of what the data in the row looked like in the database after the update(called the __ ___.) | after image |
| The log contains the entry to indicate that start of a transaction and the successful completion( ____ ) of a transaction. | commit |
| After the destruction of a database, the database is not current. The DBA executes a DBMS recovery program that applies the after images of committed transactions from the log to bring the database up to date. This method of recovery is called ? | forward recovery |
| You can use ___ __ , or ___ to recover the database to a valid state by undoing the problem transactions. | backward recovery, rollback. |
| PC-based DBMSs generally don't offer sophisticared recovery features such as journaling. TRUE/FALSE | TRUE |
| ____ is the preventiona of unauthorized acess either intentional or accidental to a database. | Security |
| The most common security features used by DBMSs are: ____,____,____,_____. | encryption, authentication, authorization, views |
| ___ converts the data in a database to a format that's indecipherable to a word processor or another program and stores it in encrypted format. | Encryption |
| The entire encryption process is transparent to a legimate user; that is, he or she is not even aware it is happening. TRUE/FALSE | TRUE |
| ___ a database reverses the encryption. | decrypting |
| ___ refers to techniques for identifying the person who is attemping to access the DBMS. | Authentication |
| The use of ___ is the most common authentication technique. | passwords |
| A ____ is a string of characters assigned by the DBA to a user that the user must enter to access the database. | password |
| ___ identify users by physical characteristics such as fingerprints, voiceprints, handwritten signatures, etc. | Biometrics |
| ___ are small plastric cards about the size of a drivers license that have built in circuits containing processing logic to identify the cardholder. | smart cards |
| Unlike individual passwords, a ___ ___ is a string of cahracters that the DBA assigns to a database and that users must enter before they can access the database. | database password |
| The DBA can use ____ ____ that specifies which users have what type of access to which data in the database. | authorization rules |
| A user's ___ specify what kind of access the user has to objects in the database. | permissions |
| The DBA usually creates groups, sometimes called ___; assigns the appropriate permissions to each group; and then assigns each user to the appropriate group based on the permissions the user requires. | workgroups |
| A ___ is a snapshot of certain data in the database at a given moment in time. | view |
| ___ refers to the right of individuals to have certain information about them kept confidential. | Privacy |
| A DBMS must follow rules so that it updates data accurately and consistenly. These rules, sometimes called ___ ___ are categorized as either key ___ ___ or data ___ ____. | integrity constraints |
| Three types of data integrity constaints are: | data type, legal values, format |
| One of the advantages of working with a DBMS is __ ___ , which is a property that lets you change the database structure without requiring you to change the programs that access the database. | data independence |
| In terms of data independence considerations, ___ or ____ a relationship is trickiest of all. | adding, changing |
| Sometimes data should be duplicated, technically called ____ at more than one physical location. | replicated |
| Replication is a two step process. First, the DBMS creates copies, called ___ of the database. Periodically, the DBMS exchanges all updated data between the master database and a replicas in a process called ___. | replicas, syncronization |
| A DBMS provides a number of ___ ___ that assist in the general maintenance of the database. | utility services |
| With a ___ ___ , you must tell the computer precisely how a given task is to be accomploshed. Basic, C++, COBOL are examples. | procedural language |
| With a ___ ___, you merely describe the task you want the computer to accomplish. SQL is an example. | nonprecedural language |
Created by:
darkskye