Database Management Systems

This type of design model in Function-oriented design describes the entities in the design that may be recorded in a data dictionary.

Session Memory consists of memory area that holds session's variables and session-related information.

When multiple users try to update the same record simultaneously, record locking prevents conflicts by ensuring only one transaction can modify the record at a time. This concurrency control mechanism prevents the lost update problem where two updates overwrite each other. Locking maintains data integrity and consistency in multi-user database environments.

Locking prevents the lost update problem, which occurs when two transactions read the same data and then overwrite each other's updates. By locking data before updating, one transaction waits for the other to complete, ensuring updates are applied sequentially. Deadlock (A) is a potential problem with locking, not a solution. Uncommitted dependency (C) and inconsistent data (D) are other concurrency issues that locking addresses.

These tools are used to manage an Oracle distributed database system. 'Site autonomy' means each server participating in a distributed database is administered independently from all other databases.

 This may leave the transactions vulnerable to dirty reads, phantom reads, etc. in the database system.

Exchanging is not a property of a transaction. The ACID properties of a transaction are:

1. Atomicity
2. Isolation
3. Durability
4. Consistency

This option is correct as a transaction is committed only after its successful completion.

These are the calls made in Oracle to perform work at some remote database.

This option is correct as checkpoints are the points scheduled at regular intervals, and involves operations like writing all the records from the main memory to secondary storage. Hence, it synchronizes database and t ransaction log files.

This option is correct as the transaction is said to be in this state, when the normal execution can no longer proceed.

This option is correct as when the execution of the transaction is stopped or aborted, it is rolled back to a state prior to its start.

This transaction in distributed databases guarantees that all statements in a transaction either commit or rollback as a unit.

The relational database model is fundamentally based on tables (relations) that store data in rows and columns. Data is organized into tables with defined relationships between them through keys. While relational databases do store records, the defining characteristic is the tabular structure. Treelike structures describe hierarchical databases, and complex logical relationships exist in network databases, not relational ones.

SQL is commonly categorized into 4 main types: DDL (Data Definition Language) for schema operations, DML (Data Manipulation Language) for data operations, DCL (Data Control Language) for permissions, and TCL (Transaction Control Language) for transaction management. Some classifications may include DQL separately, but 4 is the standard answer.