Ruby on Rails Event HCM

In Ruby on Rails, which mechanism allows you to define complex queries that can be reused and easily combined with other conditions?

• Scopes

• Validations

• Associations

• Callbacks

When does using eager loading (e.g., includes, preload, eager_load) in Active Record become important?

• When you want to perform simple queries on a single table.

• When you are accessing associations (relationships) of multiple records to avoid N+1 queries.

• When you want to optimize the speed of data access to the database.

• Eager loading does not affect query performance.

In Ruby, what is the instance_eval method used for?

• To define a method that applies to all instances of a class.

• To execute a block of code in the context of a specific instance, allowing access to instance variables and private methods.

• To create a new instance of a class based on another instance.

• To cast an object into another class type.

What is the main difference between data warehouse and operational database?

• Data warehouse stores current data, while operational database stores historical data.

• Data warehouse is optimized for analysis and reporting, while operational database is optimized for daily transactions.

• Data warehouse uses a relational model, while operational database uses a NoSQL model.

• Data warehouse only stores structured data, while operational database supports multiple data types

What is data lake, and how does it differ from data warehouse?

• Data lake stores raw and diverse data formats (structured, semi-structured, unstructured) until needed for analysis, while data warehouse typically stores cleaned and transformed data in a predefined schema.

• Data lake is a smaller version of data warehouse.

• Data lake is used for real-time applications, whereas data warehouse is used for batch analytics.

• Data lake is another term for data warehouse.

In the ETL process, what does data cleansing involve?

• Extracting data from various sources.

• Removing duplicates, handling missing values, and correcting formatting errors.

• Loading transformed data into the target system.

• Scheduling and monitoring ETL workflows.

What role does data governance play in building and maintaining an effective data system?

• Ensuring fast query performance.

• Automatically detecting and correcting data errors.

• Providing data visualization tools for end-users.

• Establishing policies, processes, and responsibilities to ensure data quality, security, and compliance.

What is Change Data Capture (CDC) and why is it important in real-time ETL systems?

• A technique for compressing data before loading it into a data warehouse.

• A process that tracks and records changes (insert, update, delete) in the source database to continuously update the target data in near real-time.

• A method for encrypting sensitive data during transmission.

• A tool for generating automated data analysis reports.

In the context of ETL, what does "orchestration" refer to?

• Managing and scheduling ETL tasks and processes, ensuring they are executed in the correct order and timing.

• Transforming data from one format to another.

• Connecting to different data sources.

• Monitoring the performance of data pipelines.

What is the main benefit of applying "metadata" in the ETL process?

• Speeding up data extraction.

• Enabling the creation of flexible, configurable, maintainable, and scalable ETL processes based on data description information.

• Reducing data storage costs.

• Improving the user interface of ETL tools.