Chapter 4 operation and maintenance-routine work of DBA

Chapter 4 operation and maintenance-routine work of DBA

(1) What are the four parts of a complete Oracle network environment?

A: A Complete Oracle network environment should include database servers, [Management Servers], Oracle HTTP servers, and management clients.

 

(4) What is a session?

A: session is a means for Oracle database servers to record database-connected users.

 

(8) What are the major differences between Oracle Database Upgrade and migration?

A: The difference is that the upgrade is to convert the installed Oracle Database Release to a later version, while the migration is to convert the installed version of the Oracle database to a later version.

 

(11) What is a transaction?

A: transactions are the concurrency control mechanisms widely used by mainstream database systems.

 

(12) What are the four features of a transaction?

A: four features of a transaction:

1. atomicity refers to that a transaction is an inseparable unit of work. Operations in a transaction either occur or do not occur.

2. Consistent transactions must transform the database from a consistent state to another consistent state.

3. isolation the isolation of transactions means that the execution of a transaction cannot be disturbed by other transactions, that is, the operations and data used in a transaction are isolated from other concurrent transactions, transactions executed concurrently cannot interfere with each other.

4. Persistent Persistence means that once a transaction is committed, its changes to the data in the database are permanent. Other operations and database faults should not affect its tasks.

 

(13) How does one deal with pending transactions in Oracle?

A: roll back to process pending transactions.

 

(14) What is the main meaning and purpose of the lock?

A: locking another common consistency and concurrency control mechanism is used to prevent multiple transactions from using the same resource at the same time.