The correct option is Cost. A cost-based query optimizer evaluates the estimated cost of executing various query execution plans and selects the one with the lowest estimated cost. This ensures efficient utilization of resources and optimal performance of the database system.

Using a query profiler can help analyze the execution path of the query and identify areas for optimization to reduce disk I/O.

In data consistency testing, the primary locations often compared are the production database, where real-time data resides, and the staging database, which mimics the production environment for testing purposes. This comparison helps ensure that the data is synchronized between these crucial databases.

Indexing plays a crucial role in optimizing query performance by providing quick access to data. It helps in reducing the time taken to retrieve records, especially when dealing with large datasets and complex queries involving joins and subqueries.

An automation framework provides faster feedback on database changes by automating the execution of database tests within the CI/CD pipeline. By integrating database testing into the automated deployment process, developers receive immediate feedback on the impact of their code changes on the database, enabling early detection and resolution of issues. This accelerates the delivery of reliable database updates in the DevOps environment.

Checksums or hash functions are used to detect any changes or corruption in data during transmission or storage by generating a fixed-size string of characters that represents the data's contents.

The "THROW" statement in SQL is used to raise a custom error message. This allows developers to generate user-defined error messages, which can provide more context and clarity when handling exceptional conditions in SQL scripts. By using the "THROW" statement, developers can enhance the error-handling capabilities of their SQL code.

Query Optimization

Stress Testing involves evaluating the performance of a system beyond its normal operational capacity, often by subjecting it to heavy loads or stress. In the context of a database, stress testing helps identify performance bottlenecks, scalability issues, and resource limitations under intense usage scenarios.

The Principle of Least Privilege is a security mechanism that helps prevent privilege escalation attacks in access control. This principle states that users should only be granted the minimum level of access or permissions necessary to perform their tasks. By adhering to this principle, organizations can minimize the risk of unauthorized access and limit the potential impact of security breaches. For example, even if a user's credentials are compromised, the damage that can be done is limited by the restricted access rights assigned to that user.